AHE-600-D03 Service Manual

Antifreeze and Water Heating Solution:

As the antifreeze type and mixture ratio is essential to the Aqua-Hot’s performance and ability to comply with regulations, the following information is being supplied to understand various types of antifreeze, the quality of water necessary, and the mixture ratio. Aqua-Hot Heating Systems Inc. recommends CAMCO’s Boiler Antifreeze -100°.

Antifreeze Types:

The following information addresses the necessary usage of a propylene glycol based “boiler “ type antifreeze in the Aqua-Hot. Propylene glycol is a safer alternative to the more toxic ethylene glycol antifreeze; however, as mandated by IAPMO (International Association of Plumbing and Mechanical Officials), only those propylene glycol based “boiler” type antifreezes deemed “Generally Recognized as Safe” (GRAS) by the FDA should be utilized.

Because of the significant impact various types of antifreeze can have on a Hydronic heating system, including the level of safety provided, it has been recognized that there is a need to provide an explanation regarding two additional prominent types of antifreeze/coolant available. The following information should be utilized as an educational means of ensuring that the proper type of propylene glycol based antifreeze is selected:

• RV & Marine Antifreeze: These types of propylene glycol based antifreeze products are formulated specifically for “winterizing” applications only. Although RV & Marine antifreeze is often “Generally Recognized as Safe” by the FDA, it should never be used in the Aqua-Hot’s Hydronic Heating System. This type of antifreeze is not formulated to transfer heat, which is essential to the heating system’s functionality and does not contain rust inhibitors. Please note, however, that RV & Marine antifreeze can be utilized to winterize the Aqua-Hot’s domestic water heating system.
• Automotive Antifreeze/Coolant: These types of propylene glycol based antifreeze products are formulated specifically to protect automotive engines against corrosion, freezing temperatures, and overheating. They also have excellent heat transfer and thermal conductivity characteristics. Although these types of antifreeze products are considered less toxic and safer than ethylene glycol for people, pets, and the environment, they are not “Generally Recognized as Safe” (GRAS) rated by the FDA. Therefore, they must be marked with a “harmful if swallowed” warning. This additional warning is required because these types of antifreeze products contain high levels of chemical inhibitors. Due to their potentially hazardous properties, they should never be used in the Aqua-Hot’s Hydronic Heating System.

Antifreeze Mixture Water Quality:

In order to ensure maximum performance and longevity of an Aqua-Hot heating system’s boiler tank and associated components, it has been determined that there is a need to use distilled, de-ionized, or soft water in combination with concentrated propylene glycol for the Aqua-Hot’s antifreeze and water heating solution,. Please note that this is only necessary when mixing concentrated propylene glycol antifreeze with water; suppliers of pre-mixed antifreeze are responsible for the use of high-quality (distilled, de-ionized, or soft) water when preparing their antifreeze for sale. Hard water possesses a high-level of calcium and magnesium ions, which deplete the propylene glycol antifreeze’s corrosion inhibitors. This, in turn, causes the antifreeze and water heating solution to begin turning acidic, which can corrode the Aqua-Hot’s boiler tank and associated components prematurely. Therefore, concentrated propylene glycol should be diluted with distilled, de-ionized, or soft water that is 80 PPM or less in total hardness. The local water agency should have up-to-date water quality reports that should indicate if the local tap water is within this guideline.

Antifreeze Terms and Mixture Ratio:

The following information addresses the process of selecting an antifreeze and water mixture ratio that provides adequate freeze, boiling, and rust/anti-corrosive protection. A 50/50 mixture ratio is recommended, which will result in a freeze point of approximately -28°F and a boil point of approximately 222°F. The following information should be utilized for the purpose of clarifying some terms commonly associated with anti-freeze.

• Freeze Point and Burst Point: Antifreeze lowers the freezing point of any liquid, to which it has been added, by preventing the formation of ice crystals; however, as the ambient temperature continues to decline, the water in the solution will attempt to attain a solid state. The point in which the water begins to solidify is termed the “Freeze Point.” Although the water in the solution has begun to freeze, producing a “slushy” consistency, the antifreeze in the solution will continue to combat the normal expansion of the solution as it freezes. The point in which the solution can begin to expand, due to colder temperatures, is called the “burst point.” Once the solution reaches the burst point, the potential is present for ruptured pipes to exist. The burst point of the antifreeze and water heating solution is dependent upon the brand of propylene glycol employed.
• Boiling Point: The Aqua-Hot utilizes the antifreeze and water heating solution as a transportation means for the heat produced from the internal processes. The antifreeze absorbs the heat created until its boiling point is reached; it is at this point that the liquid turns to a gas and is expelled to prevent the heating system from overheating. Each time the boiling point is reached, a loss of efficiency occurs because the heat produced is expelled rather than used for the function of the heating system. Therefore, a higher boiling point is desired in order to combat the loss of efficiency, which allows the antifreeze to transport the heat created from the internal process throughout the motor home where it can be used productively rather than dissipating due to its change from a liquid to a gas.
• Rust and Anti-Corrosive Inhibitors: Another major function of antifreeze is to provide protection to the internal metal components of the Aqua-Hot Hydronic heating system from corrosion and rust. Antifreeze is able to perform this function by the addition of rust and anticorrosive inhibitors, which are designed specifically to activate in a water solution.
• Summary: Antifreeze has three basic functions: freeze protection, boil over protection, and anti-corrosion and rust protection. Antifreeze is also primarily responsible for heat transfer characteristics. Therefore, as water is an excellent heat conductor, it is added to the mixture. A 50/50 solution of propylene glycol antifreeze and water is recommended to provide the best performance combination of the aforementioned functions. If excess propylene glycol exists within an antifreeze and water heating solution, the water’s heat absorption properties are compromised, which could ultimately inhibit the Aqua-Hot from providing adequate domestic hot water and interior heating. Additionally, if the antifreeze and water heating solution contains over 70 percent antifreeze, the freezing point is actually raised, resulting in less freeze protection.

AHE-600-D01 - Electric Element (s)

• Function: The “Electric switch, in conjunction with the “High/Low” switch, activates the Aqua-Hot’s Electric Heating Element (s), thereby illuminating the indicator light on the switch; reference Figure 7.
• Low: The process of moving the “High/Low” switch to the “Low” position, in conjunction with the activation of the “Electric” switch, allows one 120 VAC/2000 Watt Electric Heating Element to supply heat to the Aqua-hot’s Boiler tank. The 120 VAC/2000 Watt Electric heating Element will heat the Aqua-Hot System to the maximum operating temperature (190°F (+/-5°)) in approximately 1-2 hours.
• High: The process of moving the “High/Low” switch to the “High” position, in conjunction with the activation of the “Electric” switch, allows both 120 VAC/2000 Watt Electric Heating Elements to supply heat to the Aqua-Hot’s Boiler Tank. These two 120 VAC/2000 Watt Electric Heating Elements will heat the Aqua-Hot System to the maximum operating temperature (190°F (+/-5°)) in approximately 0.5 - 1 hour.

AHE-675-D01- Electric Element (s)

• Function: The “Electric switch, in conjunction with the “High/Low” switch, activates the Aqua-Hot’s Electric Heating Element (s), thereby illuminating the indicator light on the switch; reference Figure 7.
• Low: The process of moving the “High/Low” switch to the “Low” position, in conjunction with the activation of the “Electric” switch, allows the 120 VAC/2000 Watt Electric Heating Element to supply heat to the Aqua-hot’s Boiler tank. The 120 VAC/2000 Watt Electric heating Element will heat the Aqua -Hot System to the maximum operating temperature(190°F (+/-5°)) in approximately 1-2 hours.
• High: The process of moving the “High/Low” switch to the “High” position, in conjunction with the activation of the “Electric” switch, allows both the 120 VAC/2000 Watt and the 240 VAC/4500 Watt Electric Heating Elements to supply heat to the Aqua-Hot’s Boiler Tank. The 120 VAC/2000 Watt and the 240 VAC/4500 Watt Electric Heating Elements will heat the Aqua-Hot System to the maximum operating temperature (190°F (+/-5°)) in approximately 0.5 - 1 hour.

 

Fluid-Level Sensor:

The fluid-level sensor monitors the level of antifreeze and water heating solution within the Aqua-Hot’s boiler tank to ensure that an adequate volume exists. Troubleshoot the fluid-level sensor if one of the following conditions has occurred:

• The diesel-burner and/or electric heating element fails to operate.
• The Aqua-Hot fails to operate and the “Low Tank-Level Cutoff” indicator light on the electronic controller is illuminated.

Troubleshooting:

1. Verify that the Aqua-Hot’s boiler tank is full of the antifreeze and water heating solution.
2. Verify that the harness wire connectors are securely plugged into the fluid-level sensor.
3. Verify that the fluid-level sensor’s wires are securely installed in the terminal strip on the wire harness, as well as tightly fastened to the electronic controller.
4. Verify the functionality of the fluid-level sensor by completing the following:

• Remove the faceplate from the electronic controller.
• Install a jumper wire on the JP3 plug, between pins 15 and 16 (between “LWCO-I” and “LWCO-O”) on the electronic controller in order to bypass the fluid level sensor

If the “Low Tank-Level Cutoff” indicator light on the electronic controller extinguishes when the jumper wire is installed, inspect the wire harness for damaged or severed wires. If no wires are found to be damaged or severed, follow the instructions in this section to replace the fluid-level sensor. If, however, the “Low Tank-Level Cutoff” indicator light continues to illuminate once the jumper wire is installed, inspect the JP3 plug for damage. If no damage is found follow the instructions in this manual to replace the electronic controller.

Replacement Procedure:

Danger

Failure to disconnect all power supplies and/or to allow the heater to cool before servicing could cause serious damage or personal injury.

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected. Also, because this replacement procedure will involve the boiler tank and the potential for hot coolant, be sure the heater has adequately cooled.
2. Drain the antifreeze and water heating solution from the Aqua-Hot’s boiler tank using the drain valve, Approximately 2-3 gallons will need to be drained..
3. Disconnect the Fluid Level Sensor’s wires by separating the quick-disconnect terminals.
4. Using a 7/8 socket, remove the defective Fluid Level Sensor from the Aqua-Hot’s boiler tank.
5. Wrap the threads of the replacement Fluid Level Sensor with a thread seal tape.

Caution

Be sure to install the replacement float switch with the “N.O.” stamp on top, failure to do so, will allow the diesel/electric to come on with no antifreeze in the boiler tank.

6. Screw the replacement Fluid Level Sensor into the port on the Aqua-Hot’s boiler tank and tighten securely with a 7/8 socket, ensuring the N.O. stamp in on top.
7. Connect the replacement Fluid Level Sensor’s wires in the same configuration as the removed Fluid Level Sensors wires.
8. Refill the Aqua-Hot’s Boiler tank with the proper water/antifreeze mixture.
9. Test for proper operation

Thermostats

Valves

Pumps

Electrical-AC

Electric Heating Element: Left

Caution

There are two different Models in the Aqua-Hot 600 Series. The Aqua-Hot 600 has 2-2000 Watt 120 VAC electric heating elements. The Aqua-Hot 675 has 1-2000 Watt 120 VAC electric heating element (Right), and 1-4500 Watt 240 VAC electric heating element (Left)

The electric heating element uses AC power as an alternate power source for heating the Aqua-Hot’s boiler tank. Troubleshoot the left electric heating element if the following condition has occurred:

• There is a lack of hot domestic water and interior heat when the electric element is selected as the heating source.

Note: The 600 Series Aqua Hot may utilize a Hi/Lo Switch for the electric Heating Elements. When Troubleshooting the Left Electric Heating Element be sure the Hi/Lo switch is in the “HI” Position.

Troubleshooting:

Note: For continuous domestic hot water to be present, the diesel-burner must be selected also as a heating source.

1. Verify that the motor home is either plugged into shore power or that the generator is running to provide AC power.
2. Verify that both the “Electric Heating Element Status” and the “Heating Status” indicator lights on the electronic controller are illuminated. If the “Electric Heating Element Status” indicator light on the electronic controller is not illuminated, complete the following:

• Verify that the electric element switch on the interior switch panel is on.
• Install a jumper wire on the JP2 plug, between pins 52 and 53 (“ELECT-O” and “ELECT-I”) on the electronic controller to bypass the electric element switch

If the “Electric Heating Element Status” indicator light illuminates on the electronic controller with the jumper wire installed, check the Electric Element Switch, on the interior switch panel for functionality. If the “Electric Heating Element Status” indicator light does not illuminate on the electronic controller with the jumper wire installed, follow the instructions in this manual to replace the electronic controller.

If the “Heating Status” indicator light on the electronic controller is not illuminated, complete the following:

• Check the temperature of the Aqua-Hot’s boiler tank. If the boiler tank temperature is below 158°F, troubleshoot the control thermostat. If the boiler tank is above 158°F, the Aqua-Hot is at operating temperature and requires no heat.

3. If the “Heating Status” light is illuminate verify the Electronic Controller is sending 12 Volt DC to the A.C. Relay.

• Using a volt meter check pins 11 & 12 (“AC REL -” and “AC REL +”) for 12-Volt D.C on the JP3 plug.

If 12 Volts of DC power are not present while the “Electric Heating Element Status” and “Heating Status” indicator lights on the electronic controller are illuminated, follow the instructions in this manual to replace the electronic controller.

4. If 12 Volts of DC power are present at the relay, complete the following: follow the troubleshooting sections for both the right and the Left A.C. Relays in this section.
5. Verify that the electric heating element is receiving adequate AC power by completing the following:

• Remove the VAC access cover.
• Plug the Coach into shore power/turn generator on.
• Using an AC voltmeter, verify the presence of AC voltage at the wires for the Left Electric Heating Element.

Note: The Aqua Hot 600 will have 120 VAC present at the wires for the left electric element, while the Aqua-hot 675 will have 240 VAC present at the wires for the left electric element.

• Using an amp-meter, verify that amps are present at the element’s wires.
  • 120VAC 2000 Watt = Approximately 17 amps
  • 240VAC 4500 Watt = Approximately 17 amps
• Check the electric element’s wires for continuity by completing the following:
  • Disconnect the motor home from shore power/shut off generator.
  • Disconnect the wires from the electric heating element.
  • Disconnect the Motor Home’s incoming A.C. wires from the Aqua Hot’s AC wires.
  • Check the wires for the Left Electric Heating Element for Continuity.

6. Check the electric heating element for functionality by completing the following:

• Disconnect all power supplies.
• Remove the Electric Element access cover.
• Remove all wires from the electric heating element.
• Using an ohmmeter, check the electric heating element for proper ohm reading
  • 120 VAC 2000 Watt = 8 - 9 ohms
  • 240 VAC 4500 Watt = 12.5 - 13 ohms

If no continuity exists follow the instructions in this section to replace the electric heating element.

Replacement Procedure:

Danger

Failure to disconnect all power supplies and/or to allow the heater to cool before servicing could cause serious damage or personal injury.

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected. Also, because this replacement procedure will involve the boiler tank and the potential for hot coolant, be sure the heater has adequately cooled.
2. Drain the antifreeze and water heating solution from the Aqua-Hot’s boiler tank using the drain valve.
3. Follow the instructions for detaching the diesel burner in section 8.
4. Remove the Electric Element access cover.
5. Remove the two wires secured to the defective electric heating element by releasing the screw terminals.
6. Using a 1-1/2 inch socket, remove the defective electric heating element from the Aqua-Hot’s boiler tank.
7. Install the replacement 2000/4500-watt electric heating element into the boiler tank ensuring that the “up” lettering on the element is installed in the up position.
8. Connect the wires removed from the defective electric heating element to the replacement electric heating element and tighten the screw terminals.
9. Reinstall the Electric Element access cover.
10. Follow the Directions for reattaching the diesel burner in section 8.
11. Refill the Aqua-Hot’s boiler tank with the antifreeze and water heating solution.

Electronic Controller Features

Secondary 12 Volt-DC Battery Connection:

The electronic controller is equipped with two 12 Volt-DC power source connections, which allow for a secondary 12 Volt-DC battery connection. This 12 Volt-DC battery connection is a product-safety feature that should be utilized whenever the Aqua-Hot’s main 12 Volt-DC power supply is connected to a battery disconnect switch. This feature will ensure that the Aqua-Hot will be protected in the event that the primary power is interrupted while the diesel-burner is operating (e.g., during a burn-cycle). This secondary 12 Volt -DC battery connection will ensure completion of the required 3-minute “purge cycle” of the Aqua-Hot’s diesel burner.

Terminal Strips with Screw-Type Fasteners:

The electronic controller uses terminal strips/plugs that are equipped with screw-type fasteners, which are molded directly into the terminal strip/plug, itself. This will ensure a positive mechanical connection between the electronic controller and all wire harnesses attached to it.

Low-Voltage Reset Feature:

Whenever the Aqua-Hot’s DC power is interrupted, for longer than 5 minutes, the “low battery voltage fault” red indicator light on the electronic controller will illuminate. Reset the electronic controller by pressing the “low voltage reset” button on the electronic controller (use a thin, straight, nonmetallic object to access the button through the faceplate) or by turning off the diesel-burner switch on the interior switch panel for approximately 30 seconds, then turning the switch back on.

Replacement Procedure:

Danger

Failure to disconnect all power supplies and/or to allow the heater to cool before servicing could cause serious damage or personal injury.

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected.
2. Remove the faceplate from the electronic controller by removing the four screws securing it to the mounting bracket.
3. Disconnect the positive, negative, and secondary power (if applicable) wires from the electronic controller.
4. Disconnect the four terminal strips/plugs from the electronic controller by loosening the screws on each strip/plug and pulling each strip/plug away from the electronic controller.
5. Remove the electronic controller from the mounting bracket by unsnapping each corner.
6. Snap the replacement electronic controller into the mounting bracket.
7. Ensure that the pin jumpers are properly configured for an Aqua-Hot 600; reference information in this section for proper pin-jumper configuration. Reference Figure 25.
8. Install each terminal strip/plug back onto the electronic controller and tighten the screws on the terminal strips/plugs to secure them to the controller.
9. Connect the ground wire followed by the main 12 VoltDC power wire, then the secondary power wire (if applicable) to the appropriate screw terminals on the replacement electronic controller board. Reference Appendix A for additional wiring information.
10. Reinstall the faceplate onto the electronic controller and secure with the four screws previously removed.

Proper Pin Jumper Configuration:

1. Verify that the pin jumpers are configured as in the illustration in this section. If the pin jumpers do not match the illustration, the Aqua-Hot 600 will not function properly.
2. If the jumpers pins need to be reconfigured, simply tug gently on the black cap covering the pins to pull the black cap off.
3. Reseat the cap on the pins appropriately as per the illustration

Operational Flow Chart

Diesel-Burner Operations:

The following sequence illustrates how the Diesel-Burner operates once it is activated. Also, if diesel-burner malfunctions are experienced, use this sequence of operating as a diagnostic tool to determine at what point in the diesel burner's operation the malfunction is occurring. Use the “KEY” provided to understand each symbol shown.

Instructions for Detaching the Diesel Burner

Warning

Be sure to move the Diesel-Burner switch on the Interior Switch Panel to the OFF position and disconnect the Diesel-Burner’s power supply before detaching the Diesel-Burner from the Aqua-Hot. Failure to turn off the Diesel-Burner and disconnect power could result in serious bodily injury.

 

Caution

Be sure to clamp off the Fuel Supply and Return lines at the ports on top of the Aqua-Hot prior to beginning this procedure.

Reattaching the Diesel Burner to the Aqua-Hot

Caution

When reattaching the diesel-burner be sure to properly align the diesel-burner before tightening the eye-bolt nuts. Also, visually inspect all of the rubber grommets on the top and bottom of the diesel-burner’s castaluminum blower casing to ensure they are in place. DO NOT over tighten the eye-bolt nuts. Torque specifications are: approx. 20-40 in. lbs. An improper alignment and/or over tightening of the eye-bolt nuts can cause damage to the diesel-burner’s cast aluminum blower casing.

Diesel-Burner Motor:

The motor drives the combustion air blower and the fuel pump. In order to perform the following procedures, it may be necessary to detach the diesel burner head.

Component Test:

1. Locate the diesel-burner controller’s C-Plug and insert the probes of a DC voltmeter into the C-2 (+) and the C5 (-) locations.

• Turn the diesel switch ON and verify both the diesel burner status light and the heating status lights are illuminated on the electronic controller. If either light is not illuminated, follow the trouble shooting guide for that particular component.
• Observe the voltage level. If a normal voltage registers on the voltmeter and the motor is not operating, inspect the C-Plug Harness for loose or damaged wire connections. If the C-Plug harness and connections are in good condition, but the motor is not operational the motor must be replaced.

If there is no 12 Volts D.C. present on the C-2 pin, continue.

Note: The motor may have a flat spot and will cause the burner to work intermittently. When testing the motor be sure to test it multiple times to find the intermittent problem.

2. Verify the Electronic Controller is sending power to the diesel burner motor.

• Using a volt meter, check for 12 Volt-DC on the JP4 plug, on the B4 + pin (red wire #3). If no power is present verify the electronic controller is receiving power from the batteries.
  • Locate the main power terminals on the bottom of the electronic controller.
  • Using a volt Meter, check for 12 Volt - D.C. on the JP 8 terminal. If no voltage is present, verify that either the jumper is in place, that connects pins JP5 and JP8 together, or if there is a power wire hooked up to the JP8 terminal verify that it is receiving 12 Volt D.C. from the Motor home’s batteries.
  • If the JP8 pin does have 12 Volt D.C. +, but pin 3, on the JP4 terminal does not have power, replace the electronic controller.

RPM Test:

1. Disconnect the ignition cables from the ignition electrodes.
2. Remove the four ignition coil screws that secure the ignition coil to the protection cap.
3. Lift the ignition coil and disconnect its wires from the C-Plug harness wires prior to removing.
4. Remove the protection cap from the diesel-burner so that the motor and clutch halves are exposed.

Note: It may be necessary to remove the diesel-burner to remove the bottom two screws securing the protection cap in place. Follow the direction on detaching and reattaching the diesel burner in section 8.

5. Place a few wraps of black electrical tape around the clutch halves and then place a small piece of reflective tape over the black tape.
6. Disconnect the motor’s black (+) and brown (-) wires from the C-plug harnesses black (+) and brown (-) wires.
7. Connect the motor’s wires directly to a 12 volt DC power supply.
8. Turn the power supply ON and use a photo-tachometer to test for a proper RPM reading.
9. At approximately 12 volts DC the RPM reading should be 4500 RPM’s (+/- 300 RPM’s.) If the motor’s RPM reading is not within the above specs, the motor must be replaced.

Motor Replacement Procedure:

Danger

Be sure to move the Diesel-Burner switch on the Interior Switch Panel to the OFF position and disconnect the Diesel-Burner’s power supply before detaching the Diesel-Burner from the Aqua-Hot. Failure to turn off the Diesel-Burner and disconnect power could result in serious bodily injury.

1. Follow the directions for detaching the diesel burner in section 8.
2. Remove the four ignition coil screws that secure the ignition coil to the protection cap. Lift the ignition coil to disconnect its wires from the C-plug harness wires prior to removing. Remove the protection cap from the diesel-burner so that the motor clutch halves are exposed.
3. Remove the three hex head screws that secure the motor and flange assembly to the blower housing. Remove the motor and flange assembly along with the clutch halves. Disconnect the motor’s black (+) and brown (-) wires from the C-plug harness’ wires.

Note: Inspect the clutch halves for cracks and also ensure that the flat portion in each shaft hole is free of wear and tear. Too much play on the shaft produces a loud clacking noise. If any cracks or wear are detected, the clutch half must be replaced.

4. Detach the motor from the motor flange by removing the two Phillips heads screws that fasten the two parts together.
5. The motor must be mounted to the flange with the wires and drain hole pointing downward and the recessed edge of the motor flange pointing upward. This will ensure a proper protection cap fit.

Note: Be sure to test the diesel-burner’s bearings prior to reinstalling the motor. Worn bearings can cause lower than normal RPM readings and premature motor wear.

6. Reinstall a clutch half on both the new motor’s shaft and the combustion air blower shaft. Attach the motor and flange assembly, with the recessed edge of the motor flange in-line with the wiring access slot of the blower casing, to the blower housing with the three hex head screws.

Note: Inspect the blower casing’s O-ring for damage or wear prior to reinstalling the diesel-burner head’s protection cap. If damage or wear exists, replace the O-ring.

7. Connect the black (+) and the brown (-) wires of the new motor to the C-Plug harness’ Black (+) and brown (-) wires. Feed the C-plug harness’ yellow and brown wires back through wiring access hole in the protection cap.
8. Reinstall the protection cap. Reconnect the ignition coil wires black (+) to yellow (+) and brown (-) to brown (-) wires.
9. Reinstall the ignition coil and secure to the protection cap with the four ignition coil screws.
10. Follow the directions for reattaching the diesel burner in section 8.
11. Test for proper operation

Flame Sensor:

The flame sensor is a photo resistive device which supplies the diesel-burner’s controller with a DC voltage signal when it detects a flame. When the flame sensor senses the light of the flame, it will shut the ignition coil off, and send a signal to the diesel burner controller indicating that everything is working properly. If the flame sensor does not sense the flame, it will shut the diesel burner down in a default after 20 seconds.

Note: In order to perform the following procedures it is necessary to detach and reattach the diesel-burner head. Be sure to review the detaching/attaching instructions.

The Flame Sensor may fail in two different ways:

1. The Flame Sensor may fail to sense the flame. If it fails to sense the flame, the burner will fire up for approx. twenty seconds and then default.
2. The Flame Sensor may also fail, where it already think there is a flame before there actually is, which will result in the coil not operating. If this occurs the burner will not default, and will continue to spray raw diesel fuel into the exhaust, until the Diesel Burner Switch is turned to the OFF position.

Component Test: Ohms

1. In order to perform the following procedures it is necessary to detach the diesel-burner. Be sure to review the detaching/attaching instructions in section 9.
2. Once the diesel burner has been removed, Locate and detach the flame sensor’s green and blue wires from the C-plug harness wires.
3. Connect the flame sensor’s green and blue wires to an ohmmeter.
4. Check resistance by placing a shop rag over the flame sensor’s glass surface, to simulate a no flame condition, and then remove the rag and expose to a light source, to simulate a flame condition.
5. If the flame sensor is operating properly, the ohmmeter should register high resistance, over 100K Ω when the glass surface is covered, and less than 200 Ω when exposed to a light source.
6. If these resistance numbers cannot be obtained, verify the flame sensor’s glass surface is clean. If the flame sensor is clean and the resistance numbers cannot be obtained, the flame sensor must be replaced.

Flame Sensor Maintenance:

1. For light dirt, dust, and/or carbon deposits, simply wipe off the flame sensor with a soft cloth.
2. Should heavy carbon deposits be present, completely remove the flame sensor from the photo disc and clean with brake cleaner.

Flame Sensor Replacement Procedure:

1. In order to perform the following procedures it is necessary to detach diesel-burner head. Be sure to review the detaching/attaching instructions in section 8.
2. Remove the screw that fastens the flame sensor to the photo disc and detach the sensor’s green and blue wires from the C-plug harness’ green and violet wires, and remove flame sensor.
3. Slide the tab of the new flame sensor into the provided slot in the photo disc and secure in place with the screw. Connect the flame sensor’s green wire to the green C-plug harness wire and the blue wire to the C-plug harness’ violet wire.
4. Follow the directions for reattaching the diesel burner, in section 8 of this manual.

Ignition Electrodes

The diesel-burner’s ignition coil produces a high voltage ignition spark across the ignition electrodes, which ignites the incoming air/fuel mixture.

Cleaning and Maintenance:

1. Polish away any carbon deposits that may have baked onto the metal tips of the ignition electrodes with a course sponge.
2. If the ignition electrode’s electrical insulator is cracked or damaged, the ignition electrode must be replaced.

Note: The electrode adjustment gauge is used to set the gap between the ignition electrodes. The electrode adjustment gauge is located on the outside surface of the diesel burner head on the left hand side

Ignition Electrode Adjustment Procedure:

1. Follow the directions for detaching/reattaching the diesel burner in section 8 of this manual.
2. Using a 10mm socket, slightly loosen the retaining clamp bolt.
3. Place the electrode adjustment gauge on the nozzle manifold hex and insert the metal tips of the ignition electrodes into the appropriate notches of the electrode adjustment gauge.
4. Using a 10 mm socket, tighten the retaining clamp bolt.
5. Remove the electrode adjustment gauge and reattach to the diesel-burner head.

Replacement Procedure:

1. Using a 10mm socket, loosen and remove the retaining clamp bolt, and the retaining clamp.
2. Slide the electrode out of the photo disc.
3. To remove the electrode, hold onto the orange electrode boot, and pull firmly on the electrode.
4. Once the electrode has been removed Inspect inside the orange electrode boot for the retaining clip, which holds the electrode in place. If it is missing, replace the electrode boot.

5. Insert the new electrode into the orange electrode boot, and snap into place. Pull firmly on the electrode to make sure the retaining clip has secured the electrode in place.
6. Slide the electrode into the photo disc.
7. Install retaining clamp and retaining clamp bolt and finger tighten.
8. Follow steps 1 - 4 to properly adjust the electrodes.

Fuel Nozzle:

The fuel nozzle is simply a fuel atomizer. It reduces the diesel fuel into a fine spray which is mixed with incoming combustion air and is ignited within the combustion chamber.

Note: In order to perform the following procedures it is necessary to detach and reattach the diesel-burner head. Be sure to review section 9 for detaching and reattaching instructions.

Fuel Nozzle Component Test:

1. Follow the directions for detaching the diesel burner, in section 8, of this manual.
2. Remove both the ignition cables from the ignition electrodes, or connect a jumper wire (with alligator clips) across the metal tips of the electrodes.

Danger

Failure to connect a jumper wire across the ignition electrodes, or to remove the ignition cables from the ignition electrodes will result in a HIGH VOLTAGE shock and/ or a fire. If the ignition cables are removed, be sure to place a piece of electrical tape on the end of each cable.

3. Remove the B-plug from the diesel-burner head’s controller.
4. Turn the diesel switch ON and then plug the B-plug back into the diesel-burner controller to activate the diesel-burner. After approx. 20 seconds the fuel solenoid will “click” and a fine mist of fuel should appear from the fuel nozzle in a cone shaped spray pattern.

5. Remove the B-plug from the diesel-burner controller.
6. If the cone shaped spray pattern did not appear, follow the troubleshooting guides for the following components and verify they are operating properly:

• Fuel Solenoid
• Fuel pump  
• D.C. High Limit thermostats

7. If the components listed above are operating properly, and there is still no fuel coming out of the nozzle, replace the fuel nozzle.

Fuel Nozzle Cleaning and Maintenance:

The fuel nozzle is a precision calibrated part and cannot be cleaned or serviced. A replacement of the fuel nozzle is recommended annually.

Fuel Nozzle Replacement Procedure:

1. Use a 3/4 in. wrench to hold the fuel nozzle stand hex while loosening the fuel nozzle with a 5/8 in. wrench and remove.
2. When replacing the fuel nozzle, be sure to tighten the nozzle, loosen it a 1/4 turn, and then firmly retighten. This will establish a seated fit and avoid any leaks.

Note: An adjustment of the ignition electrodes may be necessary after replacing the fuel nozzle. Follow the ignition electrode adjustment procedure found in the ignition electrode section of this manual.

3. After replacing the fuel nozzle, reattach the diesel burner head.
4. Turn ON the diesel switch for 5 seconds, then turn it OFF. This will activate the diesel-burner’s prime cycle and flush the fuel system of any potential contaminants. Perform this procedure twice.
5. Test for normal operation.

Fuel Solenoid

The fuel solenoid allows the flow of diesel fuel to the diesel-burner’s fuel nozzle.

Note: If a long after-smoking condition exists during the diesel-burner’s purge cycle, the fuel solenoid valve kit may need to be replaced.

 

Note: In order to perform the following procedures it is necessary to detach and reattach the diesel-burner head. Be sure to review the detaching/attaching instructions.

Fuel Solenoid Component Test:

1. Locate and detach the C-plug harness’ violet (+) and Brown (-) wires from the fuel solenoid.
2. Connect the (-) lead of a 12 volt DC power supply to the fuel solenoid’s (-) electrical terminal.
3. Intermittently apply the (+) lead of the power supply to the fuel solenoid’s (+) electrical terminal.
4. Listen for the fuel solenoid to click (i.e. open and close).
5. If the fuel solenoid does not click, it must be replaced.

Fuel Solenoid Replacement Procedure:

1. Disconnect the C-plug harness’ violet (+) and brown (-) wires from the fuel solenoid.
2. Using an 8mm wrench, remove the lock nut and flat washer from the end of the fuel solenoid shaft and then pull the fuel solenoid away from the nozzle stand approximately 1/2”. Remove the fuel solenoid shaft from the nozzle manifold using a 16mm wrench. Discard the shaft and valve kit, as replacements are provided with the new fuel solenoid assembly.
3. Insert the contents of the new fuel solenoid valve kit into the new fuel solenoid shaft. Slide the new fuel solenoid onto the fuel solenoid shaft. Thread the new fuel solenoid shaft with fuel solenoid to the fuel nozzle manifold and tighten. Secure the fuel solenoid in place with the new flat washer and lock nut.
4. Connect the C-plug harness’ violet (+) and brown (-) wires to the fuel solenoid’s (+) and (-) electrical terminals.

Fuel Pump:

The fuel pump draws diesel fuel from the vehicle’s fuel tank and creates a preset pressure of 145 PSI, which is required for proper fuel atomization. Reference the illustration below for a basic overview and understanding of how the fuel pump functions.

Fuel Pump Testing Procedure:

1. Clamp off and remove the fuel return and fuel supply lines coming into the Aqua-Hot unit.
2. Attach a short piece of fuel line to both the inlet and outlet fuel ports
3. Submerse the opposite end of the temporary fuel supply line in a container of diesel fuel.
4. Place the opposite end of the temporary fuel return line in an empty container.
5. Turn the diesel switch ON to activate the diesel burner, and wait ten seconds.
6. If fuel does not flow out of the return line into the empty container, the fuel pump must be replaced.

Note: Prior to replacing the fuel pump, be sure to inspect the screen filter in the supply inlet of the fuel pump for dirt particles. Clean and/or replace if necessary. A plugged screen filter will restrict fuel from entering the fuel pump. Also, be sure to inspect for cracked or loose fittings on the supply line. A cracked or loose fitting on the supply line will allow air to enter into the fuel system.

7. If fuel does flow through the fuel pump when ran off an external source inspect the following in the motor home:

• Check the motor home fuel tank for fuel. If the fuel level is below 1/4 the Aqua-Hot diesel burner will not operate.
• Inspect the supply fuel line for kinks which would prohibit fuel flow.
• Inspect the supply fuel line for cuts, which would cause the diesel burner to suck air.
• Inspect the fuel filter, to make sure all fittings are tight, including hose clamps. Also, make sure the fuel filter is tight.
• Inspect the Aqua-Hot for loose or cracked fittings.
• Inspect the supply fuel system for loose hose clamps throughout
• Inspect the fuel pick-up tube in the tank., for loose connection and pin holes in the pick-up tube

Fuel Pump Cleaning and Maintenance:

1. Check all fuel connections for tightness.
2. Check the screen filter located in the fuel supply inlet of the fuel pump for dirt particles. Clean and/or replace if necessary.
3. To adjust the fuel pressure refer to Appendix B: Fuel pressure check and adjustment.

Fuel Pump Replacement Procedure:

Note: To perform the following procedure it will be necessary to remove the diesel burner. Follow the section on detaching and reattaching the diesel burner, section 9 of this manual.

1. Locate and disconnect the C-Plug harness wires that connect to the flame sensor and the fuel solenoid. Also, disconnect the ignition cables from the ignition electrodes.
2. Remove the retaining clip that secures the photo disc in place. Gently lift the photo disc so that it releases from the nozzle stand and the ignition electrodes.
3. Loosen the supply and return banjo bolts to remove the fuel supply and return pipes from the fuel pump. Also, disconnect the high pressure fuel pipe from both the fuel pump and the nozzle stand. Discard the high pressure fuel pipe, gasket rings, and banjo bolts , as replacements are provided in the new fuel pump kit.
4. Remove the four nozzle stand plate screws that secure the nozzle stand plate in place. Remove the nozzle stand plate by pulling on the nozzle stand until the plate releases from the cast-aluminum blower casing.
5. Remove the two pump mounting screws that secure the fuel pump in place. Turn the nozzle stand plate over and remove the snap ring from the fuel pump shaft, using snap ring pliers. Remove the nylon drive gear and then the fuel pump.
6. Attach the new fuel pump to the nozzle stand plate with the two pump mounting screws. Turn the nozzle stand plate over to install the nylon drive gear on the fuel pump’s shaft and secure in place with the snap ring. Dab the teeth of the nylon drive gear with white lithium grease (Isoflex LDS-18 is recommended.)

Note: Do not adjust the fuel pressure regulator of the new fuel pump, as it has been factory preset.

 

Caution

Inspect the nylon drive gear’s cavity inside the cast aluminum blower casting for fuel stains. If fuel stains are present, a replacement of the bearings and/or the entire blower casing may be necessary. Leaking fuel could cause bearing seizure, resulting in potential damage to the internal bore/ bearing of the blower casing.

7. Fit the nozzle stand plate inside the cast-aluminum blower casing and secure in place with the four nozzle stand plate screws. Install the grommets on the fuel return and supply banjo pipes and secure the pipes to the fuel pump with the new banjo bolts and gasket rings.
8. Reconnect the C-plug harness’ violet (+) and brown (-) wires to the fuel solenoid’s (+) and (-) electrical terminals.
9. Insert both the ignition cables into the rubber grommet and slide into the appropriate notch on the blower casing.
10. Reconnect the ignition cables to the ignition electrodes.
11. Reinstall the photo disc and secure it in place with the retaining clip.
12. Reconnect the flame sensor’s green wire to the green C-plug harness and the blue wire to the C-plug harness’ violet wire. Install rubber grommet around the harness wires, and set into place.

Note: Follow the directions for reattaching the diesel burner in section 8 of this manual.

13. Follow the directions for reattaching the diesel burner in section 8 of this manual.

Bearings:

The bearings support the combustion air blower’s shaft and allows the blower to turn smoothly.

Note: In order to perform the following procedures it is necessary to detach and reattach the diesel-burner head. Be sure to review section 9 for detaching and reattaching the diesel burner instructions

Bearing Test:

1. In order to perform the following procedure it is necessary to detach and reattach the diesel-burner head. Be sure to review the detaching and reattaching section for detaching and reattaching instructions.
2. Locate and disconnect the C-plug harness wires that connect to the flame sensor and fuel solenoid. Also, disconnect the ignition cables from the ignition electrodes.
3. Remove the four nozzle stand plate screws that secure the nozzle stand plate in place. Remove the nozzle stand plate by pulling on the nozzle stand until the plate releases from the cast-aluminum blower casing.
4. Remove the four ignition coil screws that secure the ignition coil to the protection cap. Lift the ignition coil and disconnect its black (+) and brown (-) wires from the C-plug harness wires, prior to removing. Remove the protection cap from the diesel-burner so that the motor and clutch halves are exposed.
5. Remove the three hex head screws that secure the motor and motor flange to the blower housing. Remove the motor and flange assembly along with the clutch halves. Disconnect the motor’s black (+) and brown (-) wires from the C-plug harness’ wires.
6. Remove the four blower housing screws that secure the blower housing to the blower casing. Remove the blower housing so that the combustion air blower is exposed.
7. Spin the combustion air blower by hand. Placing one of the clutch halves to the end of the shaft, assists with the spinning of the bearings.
8. If the combustion air blower rotates smoothly without any friction or noise, the bearings are in proper working condition. If the combustion air blower does not rotate smoothly and/or produces noise, the bearings are worn and must be replaced.

Replacement:

1. In order to perform the following procedure it is necessary to detach and reattach the diesel-burner head. Be sure to review the detaching and reattaching section for detaching and reattaching instructions.
2. Locate and disconnect the C-plug harness wires that connect to the flame sensor and fuel solenoid. Also, disconnect the ignition cables from the ignition electrodes.

3. Remove the four nozzle stand plate screws that secure the nozzle stand plate in place. Remove the nozzle stand plate by pulling on the nozzle stand until the plate releases from the cast-aluminum blower casing.
4. Remove the four ignition coil screws that secure the ignition coil to the protection cap. Lift the ignition coil and disconnect its black (+) and brown (-) wires from the C-plug harness wires, prior to removing. Remove the protection cap from the diesel-burner so that the motor and clutch halves are exposed.
5. Remove the three hex head screws that secure the motor and motor flange to the blower housing. Remove the motor and flange assembly along with the clutch halves. Disconnect the motor’s black (+) and brown (-) wires from the C-plug harness’ wires.
6. Remove the four blower housing screws that secure the blower housing to the blower casing. Remove the blower housing so that the combustion air blower is exposed.
7. Hold side-B of the blower casing and loosen the retaining nut located in side-A of the blower casing. Remove the retaining nut, steel drive gear and thick flat washer from the combustion air blower’s shaft. Lightly tap the threaded end of the shaft so that the combustion air blower can be easily removed from the blower casing.
8. With a pair of snap-ring pliers, remove the snap rings from both side-A and side-B of the blower casing. Push all the contents of the bearing kit out of the blower casing’s bore/bearing cavity. Discard the retaining nut, steel drive gear, snap rings, bearings, spacer tube, and washers, as replacements are provided in the new bearing kit.
9. Install a new snap ring into side-A of the blower casing. Once the snap ring is in place, insert the remaining contents of the new bearing kit into side B of the blower casing, starting with the wave washer. Secure the bearing kit assembly in place with the remaining snap ring.
10. Inspect the combustion air blower for warping and/or damage. If warping or damage is visible, the combustion air blower must be replaced.
11. Reference Figure 58 for exact placement of the three washers that slide over the threaded end of the combustion air blower’s shaft prior to installation. Failure to follow the correct order and direction of the dished surfaces on the washers will result in a restricted rotation of the combustion air blower.
12. Slide the combustion air blower’s shaft (with the three washers) up through the bearing kit assembly until the threaded portion appears on side-A of the blower casing. Place the new thick flat washer and steel drive gear on the threaded end of the combustion air blower’s shaft. Thread the new retaining nut on the combustion air blower’s shaft until it is finger tight (DO NOT TIGHTEN.)

13. Place a feeler gauge between the combustion air blower and the flat surface of the blower casing. Slowly tighten (or loosen) the retaining nut, holding the combustion air blower, until a .003-.005 gap is achieved. Remove feeler gauge.
14. Spin the combustion air blower to ensure a friction free rotation.
15. Reattach the blower housing to the blower casing using the four blower housing screws. Reinstall the clutch half on both the motor’s shaft and the combustion air blower’s shaft. Attach the motor and flange assembly, with the recessed edge of the motor flange in-line with the wiring access slot of the blower casing, to the blower housing with the three hex head screws. Reconnect the black (+) and brown (-) wires of the motor to the C-plug harness’ black (+) and brown (-) wires. Feed the C-plug harness’ yellow and brown wires back through the wiring access hole in the protection cap.
16. Reinstall the protection cap. Reconnect the black (+) and brown (-) wires of the ignition coil to the C-plug harness’ yellow (+) and brown (-) wires. Reinstall the ignition coil and secure to the protection cap with the four ignition coil screws. Reconnect the ignition cables to the ignition electrodes.
17. Fit the nozzle stand plate inside the cast aluminum blower casing and secure in place with the four nozzle stand plate screws. Reattach the fuel supply and return lines to the diesel-burner head.
18. Reconnect the blue (+) and brown (-) wires to the fuel solenoid’s (+) and (-) electrical terminals. Also, reconnect the flame sensor’s green wire to the green C-plug harness wire and the blue wire to the C-plug harness’ violet wire.
19. Follow the instructions for reattaching the diesel burner, in the detaching/reattaching section in this manual.

Ignition Coil:

The ignition coil produces a high voltage ignition spark (approx. 8000 volts), which is released across the metal tips of the ignition electrodes during the initial diesel-burner start-up.

Use extreme care when testing the ignition coil, as a High Voltage Shock may result.

Note: In order to perform the following procedures it is necessary to detach and reattach the diesel-burner head. Be sure to review the section for detaching and reattaching the diesel burner.

Component Test:

1. Remove the four ignition coil screws that secure the ignition coil in place.
2. Disconnect the ignition coil’s black (+) and brown (-) wires from the C-plug harness’ yellow (+) and brown (-) wires.
3. Connect the ignition coil wires directly to a 12 volt DC power supply (i.e. black (+) wire to (+) lead and brown (-) wire to (-) lead).
4. Turn the power supply ON and watch for a spark to appear across the metal tips of the ignition electrodes. If a spark does not appear, the ignition coil must be replaced.

Note: Some ignition coils are intermittent and will need to be tested numerously. If the Ignition Coils tests good and it still will not operate it is possible the Electronic Controller is defective.

 

Caution

Before replacing the ignition coil: Verify the ignition electrodes are not cracked or broken. Verify that the ignition electrodes are adjusted properly. Ensure the electrode boots are securely holding the electrodes in place. Ensure the electrode boots are not broken inside the ignition coil wires.

Ignition Coil:

Note: In order to perform the following procedures it is necessary to detach and reattach the diesel-burner head. Be sure to review the section for detaching and reattaching the diesel burner.

Replacement Procedure:

1. Disconnect the ignition cables from the ignition electrodes. Remove the four ignition coil screws that secure the ignition coil to the protection cap. Lift the ignition coil and disconnect its wires from the C-plug harness wires, prior to removing.
2. Disconnect the ignition cables, on the defective ignition coil, from the ignition electrodes.
3. Connect the new ignition coil cables, to the ignition electrodes.
4. Connect the new ignition coil’s black (+) and brown (-) wires to the C-plug harness’ yellow (+) and brown (-) wires. Attach the ignition coil to the protection cap with the four ignition coil screws, then reconnect the ignition cables to the ignition electrodes.

Note: If the new ignition coil does not function, check wire connections and ensure they are properly connected.

5. Follow the instructions for reattaching the diesel burner and test for proper operation.

Diesel-Burner Controller:

The diesel-burner controller operates all the components of the diesel-burner head and safely shuts the heater OFF in the event of an overheat, flameout, and low voltage condition. It also receives diesel burner operation status signals from the flame sensor, VDC control thermostat, and VDC high-limit thermostat.

Component Test:

The following conditions must exist prior to performing the diesel-burner controller circuit tests on the following page. If one of the conditions below does not exist, please contact our technical support department at 1-800-685-4298 for additional assistance.

Condition #1

A battery voltage level between 11.5 to 14.0 volts DC must be present at the diesel-burner controller during all testing. It may be necessary to perform a voltage check to ensure that this condition exists. To perform the voltage check, locate the dieselburner controller’s B-plug, and insert the probes of a DC voltmeter into the B-4 (+) and B-2 (-) locations.

Condition #2

A voltage level of between 11.5 to 14.0 volts must be present at the diesel ON/OFF switch circuit of the diesel-burner controller during all testing. It may be necessary to perform a voltage check to ensure that this condition exists. To perform the voltage check, locate the diesel-burner controller’s B-plug, and insert the probes of a DC voltmeter into the B-1 (+) and B-2 (-) locations. Turn the diesel switch ON and observe the voltage level.

Ground Circuit Test:

Locate the diesel-burner controller’s B-plug and C-plug. Insert the probes of a DC voltmeter into the B -4 (+) and C-5 (-) locations and turn the diesel switch ON. If a voltage reading does not register on the voltmeter, the diesel-burner controller must be replaced. If voltage is present, proceed to the next circuit test.

VDC/VAC Control Thermostat Circuit Test:

Locate the diesel-burner controller’s B-plug and C-plug. Insert the probes of a DC voltmeter into the C -1 (+) and B-2 (-) locations and turn the diesel switch ON. If a voltage reading does not register on the voltmeter, the diesel-burner controller must be replaced. If voltage is present, proceed to the next circuit test.

VDC High-Limit Thermostat Circuit Test:

Locate the diesel-burner controller’s B-plug and C-plug. Insert the probes of a DC voltmeter into the C -4 (+) and B-2 (-) locations and turn the diesel switch ON. If a voltage reading does not register on the voltmeter, the diesel-burner controller must be replaced. If voltage is present, proceed to the next circuit test.

Motor Circuit Test:

Locate the diesel-burner controller’s B-plug and C-plug. Use a jumper wire to make a connection from the C-1 location to the C-7 location. Turn the diesel switch ON and insert the probes of a DC voltmeter into the C-2 (+) and C-5 (-) locations. If no voltage reading registers on the voltmeter, the diesel-burner controller must be replaced. If voltage is present, proceed to the next circuit test.

Be sure to remove the jumper wire that was used to make the connection from the C-1 location to the C-7 location. A failure to do so will result in an overheating condition during normal operation.

Ignition Coil Circuit Test:

Turn the diesel switch OFF and locate the diesel burner controller’s C-plug. Also, locate the VDC high-limit thermostat and disconnect it’s 2-way male plug from the (white plastic) 6-way female connector. Insert the probes of a DC voltmeter into the C-8 (+) and C-5 (-) locations and turn the diesel switch ON. If a voltage reading does not register on the voltmeter 18-25 seconds after the initial start-up the diesel-burner controller must be replaced.

Note: Be sure to reconnect the VDC high-limit thermostat’s 2-way male plug to the 6-way female plug. The diesel -burner will not ignite during normal operation if the VDC high-limit thermostat is left disconnected.

Be sure to remove the jumper wire that was used to make the connection from the C-1 location to the C-7 location. Failure to do so will result in an overheating condition during normal operation.

Replacement Procedure:

1. Remove both the B-plug and the C-plug from the diesel-burner controller. Gently pry away each side of the diesel-burner controller bracket from the diesel-burner controller’s locking posts with a flat-head screw driver. Once the locking posts have been released, pull on the diesel-burner controller to remove it from the diesel-burner head.
2. Slide the new diesel-burner controller into the diesel-burner controller bracket. Push down on the diesel-burner controller until the locking posts snap into the bracket slots.
3. Reconnect the B-plug and the C-plug.

Black Smoke

1. Is the heater experiencing a low voltage condition.

• Fire up the generator or plug the coach into shore power.

2. Is the Exhaust Pipe Damaged or Restricted?

• Inspect the exhaust pipe for damage, or excessive bends.

Note: The Access cover will need to be removed to check the following.

3. Is the Air Intake closed off?

• The Air Intake is located on the bottom of the diesel burner, and should be adjusted to the halfway point.
• There is a rubber air intake sleeve on the air intake, and If it is collapsed it will need to be replaced.

4. Is the Protection Cap damaged or cracked?

• Inspect the protection cap for cracks or holes.

5. Are the Right and Left Grommets Worn out?

• Are they hard and brittle?
• Has the rubber been cut out, around the wires?
• Are they positioned correctly.

6. Is the burner properly positioned and secured properly.

• Inspect the burner to ensure it is aligned properly.
• Tighten the Eye Bolts securing the burner in place.

Caution

Do not over tighten the eye bolts, or damage to the diesel burner may result. Tighten the Eye Bolts to 20-40 inch pounds.

 

Note: The Diesel Burner must be removed to check the following.

7. Is the Photo Disc bent or tight.

• The photo disc must be free floating. If it is bound up, it will not seat against the combustion chamber.

8. Is the Combustion Chamber warped or melted?

• Remove the Combustion Chamber and inspect for signs of damage. Inspect the aluminum for signs of warping, or melted aluminum.

9. Is the Nozzle bad?
10. Is the Fuel Pressure set at 145 PSI?

• Check the fuel pressure with the fuel pressure gauge.

Note: The Diesel Burner will need to be tore down to check the following.

11. What are the RPM’s of the Combustion Blower Motor?

• The RPM’s should be 4500 rpm at 12 VDC.
• If the motor is running slow inspect the bearings before replacing the blower motor.

12. Are the bearings faulty?

• The bearings should spin freely, and sound smooth.
• Bearings that are bad will slow the motor down.

13. Is the Impeller fan gapped properly?

• The impeller fan should be gapped between .003 - .005 thousands

Note: Anything that throws off the air fuel mixture in the combustion chamber is a possible cause of black smoke

Blue/White Smoke

1. If the heater is smoking blue/white smoke during the start up or shut down cycle:

• Is the Fuel Solenoid functioning properly
  • Test the fuel solenoid and make sure it engages as soon as power is put to it. Any delay in the fuel solenoid may cause blue/ white smoke.
  • Remove the fuel solenoid and inspect the plunger for any damage or debris that may interfere with the fuel shutting down.
• Is the Nozzle Tower Damaged?
  • Inspect the area where the nozzle screws in for cracks in the brass.
  • Remove the fuel solenoid and inspect the plunger seat for poorly machined brass.
• Is the Diesel Burner short cycling (turning off and on more frequently than normal).
  • Test the control thermostat to ensure it is operating within the proper range.
  • Ensure someone has not turned the heater off and on several times.

Note: Webasto says it is normal for there to be a short puff of smoke after the flame has shut down, due to the nozzle tower emptying the fuel out.

2. If the heater is smoking blue/white smoke during the Burn Cycle:

• Are the electrodes adjusted properly?
  • Use the gauge on the side of the diesel burner to properly adjust the ignition electrodes.
• Are the air bubbles in the fuel system? i. If the fuel pump is sucking air at any point, on the supply fuel system, the heater will continuously puff out blue/white smoke. 
• Is the Fuel Nozzle Bad?
• Is the Fuel Pressure Adjusted properly?
  • The fuel pressure should be 145psi
• Is the Fuel Pump Leaking?
  • If the fuel pump is leaking it will need to be replaced.
• Is the Ignition Coil igniting every time?
  • An intermittent Ignition Coil will allow fuel to spray into the combustion chamber, without igniting it every time.

Lack of Interior Heat

• Is the Diesel Burner /Electric Heating Element working properly?
• Is the Heater up to operating temperature?
• Is the Interior Room Thermostat Calling for heat?
• Is the Zone Circulation Pump operating?
• Are the Heat Exchanger fans operating?
• If the Heat Exchanger Fans, and the Zone Circulation Pumps are operating check for the following:
  • Stuck Check Valve
  • Inspect for a Kinked plumbing line.
  • Is there a Lack of antifreeze in the boiler tank.
• Is the Low Temperature Cutoff Thermostat light, on the electronic controller, out?
• Is the Electronic Control Board working properly?

Lack of Domestic Hot Water

1. Things to keep in mind when trouble shooting a heater for a lack of hot water.

• The Diesel Burner must be on for continuous hot water
• The Heater is only rated for a water flow of 1.5GPM.
• The heater is only rated for a 55°F Temperature rise on the cold water coming in.

2. Check the following if there is a lack of domestic hot water:

• Is the heater bypassed?
• Has the Outside water faucet been left on?
  • If both the cold and hot valves are left in the on position, the outside water faucet acts like a secondary mixer valve, and the remaining hot water faucets will only produce warm water.

Note: The Electric Element is designed to be used during low heat demand situations, and will not supply continuous hot water.

• Has the Internal Washing Machine Valve gone bad?
  • If both the internal washing machine valve has gone bad it acts like a secondary mixer valve, and the remaining hot water faucets will only produce warm water.
• What is the Antifreeze concentration?
  • The proper antifreeze concentration should be between 30%-50% antifreeze. If the concentration is over a 50% antifreeze concentration the antifreeze does not transfer the heat properly and there will be a lack of domestic hot water.
• What is the operating range of the control thermostat?
  • 155 ° F to 185 °F
• What is the Water Flow (GPM)
  • The water flow must be 1.5GPM or less
  • Test the water flow where the customer is complaining about lack of hot water (i.e. shower, sink, etc.)
• Is the Mixer Valve functioning properly.
  • The mixer valve’s adjustment knob should turn freely. If the adjustment knob does not have free movement, the mixer valve must be replaced.

On the Front-Side of the Aqua-Hot: A: Fluid Level Sensor B: Control Thermostat C: Drain Valve Assembly D:Electric Heating Element (s).  One electric element is located on the left of the diesel burner, and the diesel burner will need to be removed to be able to inspect it. E: Circulation Pump (s).  When checking the circulation pumps be sure to inspect the plumbing for the hoses, the tank ports, and the circulation pump. F: Combustion “Burn” Chamber leak When the Combustion “Burn” Chamber leaks, the antifreeze will run out the tip of the exhaust pipe.

 

On the Top of the Aqua-Hot: A: Radiator Cap  Bad seal Loose  B: Expansion Tank Tubing Cracked Loose C: Filler Neck Bent Broken nipple Bad solder joint D: Supply and Return interior zone heat ports. Tubing/hose Brass fittings

 

Instructions for Checking Fuel Pressure

Step 1: Remove the diesel-burner

Refer to the section on detaching/reattaching the diesel burner, to detach the diesel burner.

Step 2: Remove the Fuel Nozzle

Using a 5/8” and a 3/4” wrench remove the fuel nozzle.

Step 3: Installing the fuel pressure gauge

Using a 5/8” and a 3/4” wrench install the fuel pressure gauge.

Turn the diesel burner switch to the on position. A pressure will register on the fuel pressure gauge once the fuel solenoid opens (after approx. 10-20 seconds).

Instructions for Adjusting Fuel Pressure

Step 1: Follow the directions for Checking the Fuel Pressure in this section.

Step 2: Adjust The Fuel Pressure to 145 PSI

Turn the diesel burner switch to the on position. A pressure will register on the fuel pressure gauge once the fuel solenoid opens (after approx. 10-20 seconds.

Once the fuel solenoid has been activated, and the fuel pressure gauge is registering a pressure, the fuel pressure can be adjusted. To increase the fuel pressure turn the pressure adjustment screw clockwise, and to reduce the fuel pressure, turn the pressure adjustment screw counter clockwise.

Aqua-Hot Maintenance Procedure:

Step 1: Test Run the Diesel Burner

1. Turn the Diesel-Burner Switch to the on position.
2. After the Diesel-Burner has ignited, inspect the exhaust for smoke.
3. Shut the Diesel-Burner off, and wait for unit to completely shut off.

Step 2: Replace the Fuel Filter

1. Locate Fuel Filter.
2. Using hose pinch off pliers, clamp off both fuel lines going to the fuel filter. Reference figure D2.
3. Replace fuel filter, with proper replacement canister.
4. Remove hose pinch off pliers

Step 3: Run the Diesel Burner

1. Turn the Diesel-Burner Switch to the on position.
2. After the Diesel-Burner has ignited, let it burn for 1 - 2 minutes to purge the old fuel out of the nozzle holder, to prevent contamination of the replacement nozzle.
3. Shut the Diesel-Burner off, and wait for unit to completely shut off.

Step 4: Remove The Diesel Burner

1. Locate the Diesel-Burner’s Controller and disconnect both plugs. Failure to do so may result in the Diesel burner igniting.

2. The Diesel-Burner is secured to the Aqua-Hot with two 10mm nuts that can be loosened, and swung out of the way by using a 10mm socket wrench with a 10 inch long extension.

3. Carefully pull the Diesel-Burner away from the Aqua-Hot 4 to 5 inches before rotating the burner, and then remove.
4. Clean and Inspect the Combustion Chamber and Heat Transfer Tabs.

Remove the combustion chamber by pulling it straight out, approximately 16 inches

Once the combustion chamber has been removed. Use a long handled wire brush, and brush the heat transfer tabs, to loosen soot deposits. Failure to do so will reduce the Aqua-Hot’s heat transfer capabilities.

Inspect the Combustion Chamber for damage or signs of warping.

• Remove and Inspect the aluminum Air Swirler for signs of warping. If any part of the Air Swirler is warped the combustion chamber must be replace.
  • Inspect the outer ring that the photo disc seats against for signs of warping.
  • Inspect the back side of the Air Swirler for signs of warping between screws.

Step 6: Reinstall the Combustion Chamber

Reinstall the Combustion Chamber into the Aqua-Hot. Be sure to install the combustion chamber Seam in the 12:00 position. Failure to do so, may cause a crack to appear along the seam.

Step 7: Inspect Diesel-Burner

Inspect the following:

1. Electrodes

• damaged
• improperly adjusted

2. Fuel Pump

• leaks

3. Photo disc

• warped
• bent

4. Harness & Ignition Coil Wires

• crack or bare wires
• Hard or brittle wires

5. Flame Sensor

• cracked
• overheated (purple color)
• melted wires
• dirty

6. Rubber Grommets

• hard/brittle
• rubber has been cut out
• right/left

7. Broken or cracked “Ears”

• due to over tightening of eyebolts.

Step 8: Clean Ignition Electrodes and Flame Sensor

1. Ignition electrodes

• Polish away any carbon deposits that may have baked onto the metal tips of the ignition electrodes with a course sponge.

2. Flame Sensor

• For light dirt, dust, and/or carbon deposits, simply wipe off the flame sensor with a soft cloth.
• Should heavy carbon deposits be present, completely remove the flame sensor from the photo disc and clean with brake cleaner.

Step 9: Replace The Fuel Nozzle

1. Use a 3/4 in. wrench to hold the fuel nozzle manifold hex, while loosening the fuel nozzle with a 5/8 in. wrench and remove.
2. When replacing the fuel nozzle, be sure to tighten the nozzle, loosen it a 1/4 turn, and then firmly retighten. This will establish a seated fit and avoid any leaks.

Step 10: Adjust Ignition Electrodes

1. Using a 10mm socket, slightly loosen the retaining clamp bolt.
2. Place the electrode adjustment gauge on the nozzle manifold hex and insert the metal tips of the ignition electrodes into the appropriate notches of the electrode adjustment gauge.
3. Using a 10 mm socket, tighten the retaining clamp bolt.
4. Remove the electrode adjustment gauge.

Step 11: Inspect Photo Disc

 

1. If the photo disc is not free floating, the electrode clamp bolt has been over-tightened, and has bent the electrode clamp. Using a 10mm socket remove the electrode clamp, and re-straighten.

• Lay the clamp’s beveled side down on a solid flat surface and align the thick end of the punch at dead center. Tap the punch lightly until the retaining clamp returns to proper form.

Step 12: Re-Install Diesel Burner

1. Align the Diesel-Burner with the Hydro-Hot, using the alignment tabs welded on the Hydro-Hot.
2. Swing the Eye Bolts around the “Ears” on the diesel burner and securely tighten, using a 10mm socket with a 10 inch long extension.

Step 14: Plug in the diesel-burner’s controller and mount

1. Locate the Diesel-Burner’s Controller and connect both plugs.

Step 15: Re-Install the Aqua-Hot Access Cover

1. Reinstall the Aqua-Hot’s access cover .
2. Securely tighten the five screws securing the access cover in place.

Step 15: Test for Normal Operation

1. Turn the Diesel-Burner switch on, and let the diesel burner run for a complete cycle, until it shuts off on it’s own.
2. After the Diesel-Burner has shut off, turn on the interior heat/run hot water, until the Diesel Burner cycles back on. When the diesel burner cycles back on, check the exhaust for signs of smoke.