AHE-250-DO2 Use and Care Guide

Safety Instructions

Safe Operation

The Aqua-Hot Heating system consists of an electric heating element and a burner. The electric element and/or the burner heat a propylene glycol and water mixture, that flows through tubing and into heat exchangers to heat a zone that calls for heat. The heating system also heats domestic water for hot water use in the shower or at hot water faucets. To safely and properly operate the Aqua-Hot 200 Series heater, please make sure that the fluid level is up to the “COLD” level line on the expansion tank before heating. If the heater has already been activated and running, the fluid should be to the “HOT” level. Locate the Aqua-Hot switch panel inside the coach (contact the vehicle manufacturer if unable to find), turn on either the “ELECTRIC” switch to turn on the Electric Element or “BURNER” switch to turn on the burner. It will take approximately 20 minutes to get the glycol fluid up to operating temperature. After the tank is to temperature, you can turn on the heat on your coach thermostat or run hot water.

General Care

The Aqua-Hot 200’s fluid levels should be checked regularly to ensure it is at the proper level. It should be checked when the Aqua-Hot is at maximum operating temperature, when the burner completes a cycle or when the electric element disengages. The level should be at the “HOT” mark on the expansion tank.

It is necessary to take precautions during any user maintenance. Note that the fluid will be very hot, and any scalding hot vapor or coolant could cause serious burns or injury.

Intended Use

This manual explains the operation and care of the Aqua-Hot heating system. These instructions are approved for the Aqua-Hot 200 series model for recreational vehicles only. Not for use in boats.

Service and repairs may only be carried out by an authorized, factory-trained Aqua-Hot technician. The heating system must be installed/serviced in accordance with local codes, or, in the absence of local codes, follow NFPA 1192.

• The vehicle owner is responsible for correct operation of the appliance.
• Make sure to properly winterize the Aqua-Hot’s domestic water system when not in use and/or any time the heater is stored where freezing temperatures may be experienced. The Aqua-Hot warranty will not cover claims for freeze damage. Please refer to page 14 for proper winterization of the Aqua-Hot.
• In order to provide the best freeze protection, boil-over protection, anti-corrosion, and rust protection, a mixture of 50/50 Propylene Glycol antifreeze and distilled water is recommended.
• The mixture may be modified to provide the most adequate freezing, boiling, and rust/anti-corrosive protection. A 50/50 mixture of Propylene Glycol and distilled water has a freeze point of approximately -29°F and a boiling point of approximately 223°F. Reference page 15 for measuring the antifreeze mixture with a refractometer. 

Hot Water System

When hot water is requested, domestic water from the coach’s fresh water tank is transported through the domestic copper coil, that goes into the boiler tank located in the Aqua-Hot. The water is then heated by the heated antifreeze and distilled water solution. The heated domestic water then flows through the tempering valve to be mixed with cool water from the fresh water tank to achieve an appropriate temperature before it flows to the faucet.

Component Callouts

 

	1. Access Cover Screw
	2. Drain Valve
	3. 3-Way Valve
	4. Diesel Burner Controller
	5. Tempering Valve
	6. Diesel Burner Assembly
	7. Interlock Switch
	8. Domestic Cold Water Inlet
	9. Domestic Hot Water Outlet
	10. 120V AC Connection
	11. Diesel Fuel Return Port
	12. Diesel Fuel Supply Port
	13. Expansion Tank Connection
	14. Heating Zone Return Port
	15. Heating Zone Outlet Port
	16. Boiler Tank
	17. Domestic Hot-Water Coil
	18. Relay Control Board
	19. Zone Circulation Pump

Note: The side and top panels in the view below have been made transparent to aid in the explanation of the heater. DO NOT remove these panels. Doing so risks irreparable damage to the Aqua-Hot. Only remove the service panel for service.

Aqua-Hot System Features

System Features

The Aqua-Hot 250 Diesel Series is a Low-Emissions Hydronic Heating System that significantly improves your level of comfort, decreases harmful emissions released into the atmosphere, and adds thousands of dollars in value to your coach.

The Aqua-Hot Heating System is a 2-in-1 system

1. Interior Heating System: Provides quiet, comfortable interior heat and even temperatures.
2. Tank-less Hot Water System: Provides a steady flow of continuous hot water.

The Aqua-Hot is powered by TribridHot™ technology and uses one or a combination of the following heat sources:

• Burner: This is the Aqua-Hot’s most powerful heat source. The burner must be on for the Aqua-Hot to provide continuous hot water. The burner must be on for the AquaHot to provide interior heat in colder conditions.
• 120VAC Electric Element: When plugged into shore power, the electric element lets you use the power you are already paying for to provide heat in mild conditions and meet your light duty hot water needs.

Bring the Aqua-Hot to Operating Temperature:

Your Aqua-Hot hydronic heating system heats a propylene glycol antifreeze and distilled water solution that is stored in the Aqua-Hot’s boiler tank. This water and antifreeze solution must be up to operating temperature before the Aqua-Hot will provide interior heat or comfortable hot water. To bring the Aqua-Hot up to temperature, turn the Burner switch to the ON position. Depending on the ambient temperature, it may take up to 10 minutes for the Aqua-Hot’s water and antifreeze solution to reach operating temperature.

Once the tank is up to operating temperature, the electric element may be used to maintain the operating temperature and provide light duty hot water and interior heat. For continuous hot water, or for heat in colder conditions, it is recommended to utilize the burner.

Note: This Aqua-Hot product utilizes a propylene glycol based antifreeze and water heating solution. This propylene glycol based solution is a boiler-type antifreeze that is “Generally Recognized As Safe” (GRAS) by the FDA. For additional information regarding this “GRAS” antifreeze product, see the Care & Maintenance section of this guide, or contact Aqua-Hot Technical Support at 574-AIR-XCEL (574-247-9235) or visit the website at www.aquahot.com.

Note: This product label is attached to the side of the Aqua-Hot and provides a ready reference to specifications, test standards, and important safety notices.

Operational Overview

The heating features are powered by a 12V DC diesel burner and a 120V AC electric heating element. These maintain the temperature of the Aqua-Hot’s antifreeze and water heating solution to provide hot water and interior heat.

Burner: The burner is the Aqua-Hot’s primary and most powerful heat source, and provides all of the heating and hot water needs when cold temperatures exist, and/or when there is a high demand for hot water. It can be activated by turning the burner switch to the ON position (see below).

Electric Element: The electric element is the Aqua-Hot’s secondary heat source and can be used when plugged into shore power. The electric element provides heat when moderate temperatures exist (50°F or higher) and/or when there is a low demand for hot water. It can be activated by turning the electric switch to the ON position (see Figure 3).

Switches: The Aqua-Hot heating system is controlled by one or two switches: the burner switch and/or the electric element switch. When one or both switches are in the ON position, it will supply the necessary heat to the boiler tank. Keep in mind that the Aqua-Hot must be at operating temperature for the heating zones and hot water to function properly.

Controlling Heat Levels with Room Thermostat:

When the Aqua-Hot is on and up to operating temperature, adjust the room thermostat to the desired temperature and it will automatically activate the Aqua-Hot’s heating functions to maintain the desired interior temperature.

Different manufacturers may use different types of thermostats. Please contact the dealer or manufacturer for the exact type, location, and thermostat operation.

Using Hot Water:

When the Aqua-Hot is on and up to operating temperature, simply open a hot water faucet and a continuous supply of hot water will be present within a few seconds.

The Aqua-Hot system is known as a tank-less, continuous water heating system because hot water is not stored in a tank. Instead, when the burner and/or electric element switch is ON and the Aqua-Hot is at operating temperature, the water is automatically heated as it is being used. Remember the burner must be on for continuous hot water.

When hot water is requested, domestic water from the coach’s fresh water tank is transported through the domestic water line, that goes into the boiler tank located in the AquaHot. The water is then heated by transfer from the heated antifreeze and distilled water solution. The heated domestic water then flows through the tempering valve to be mixed with cool water from the fresh water tank to achieve an appropriate temperature before it flows to the faucet.

Operational Flow Chart

Maintence Schedule 

Monthly Maintenance

Check the Aqua-Hot’s antifreeze and water heating solution to ensure that it is at the proper level. This can be accomplished by visually checking the coolant level in the Aqua-Hot’s expansion tank; reference Figure 5 on page 12.

Please note that the coolant level should be checked ONLY when the Aqua-Hot is at maximum operating temperature. This should be done immediately after the diesel burner has completed a cycle or after the electric element disengages.

At maximum operating temperature, the antifreeze and water heating solution should be at the level marked “HOT” on the expansion tank. Run the interior heating zones until you feel warm air blowing out of the heat exchangers.

It is also recommended to run the burner once a month for a full cycle (at least 20 minutes) to ensure optimum heater condition.

Replenishing the Antifreeze and Water Heating Solution

If the antifreeze and water heating solution needs replenishing, remove the cap for the expansion bottle and fill it to the “HOT” mark. Replace the expansion bottle cap when this is complete. DO NOT operate the unit without first replacing the cap of the bottle. Reference Figure 5 for additional information. Excess air will escape through this bottle as the stir pump of the unit operates. While bleeding this system of air it will be necessary to continue to fill the bottle until this process is complete.

Reference the Appendix on page 15 for the proper tool and instructions for usage in measuring the system’s antifreeze mixture ratio.

The Aqua-Hot does not need regular replacement of the antifreeze and water heating solution, but in the event that more antifreeze is required, contact Aqua-Hot Heating Systems to purchase antifreeze, or for guidance in selecting an appropriate antifreeze product for use with this unit.

In order to provide the best freeze protection, boil-over protection, anti-corrosion, and rust protection, a mixture of 50/50 propylene glycol antifreeze and distilled water is recommended.

The mixture may be modified to provide the most adequate freezing, boiling, and rust/anti-corrosive protection. A 50/50 mixture of propylene glycol and distilled water has a freeze point of approximately -29°F and a boiling point of approximately 223°F. Reference page 15 for measuring the antifreeze mixture with a refractometer.

Annual Maintenance

Diesel: To keep the diesel burner running smoothly, a tune-up or annual service should be performed on the unit. An annual service consists of a new fuel nozzle and fuel filter. To ensure best diesel burner performance, always use the recommended fuel nozzle and fuel filter when replacing these parts.

Note: For additional information regarding this propylene glycol based boiler-type antifreeze that has been “Generally Recognized As Safe” by the FDA, please reference pages 13 & 14, contact Aqua-Hot Heating Systems Technical Support Department at 574-AIR-XCEL (574-247-9235), or visit the website at www.aquahot.com.

Winterizing the Aqua-Hot

The Aqua-Hot’s domestic water heating system must be completely drained of domestic water at any time the heater is stored where freezing temperatures may be experienced.

Note: The Aqua-Hot can continue to be used for interior heat once the domestic hot water system has been winterized.

Please follow these instructions when winterizing the Aqua-Hot domestic water heating system. Reference Figure 4 below for a system overview.

1. Completely drain the fresh water storage tank.
2. Disconnect the domestic water demand pump suction line from the fresh water storage tank.
3. Attach an adequate piece of hose onto the suction side of the domestic water demand pump.
4. Place the opposite end of the hose into an adequate supply of non-toxic RV winterization antifreeze (FDA certified as “GRAS” must be used) and allow the fluid to pump through.
5. Open and close all interior and exterior water faucets one at a time, until ONLY pure RV antifreeze is present. Perform this procedure for both cold and hot water faucets.
6. Remove the hose and reconnect the domestic water demand pump’s suction line to the fresh water storage tank.

De-Winterization

To de-winterize the Aqua-Hot system, completely fill the fresh water storage tank. Open and close the interior and exterior faucets, one at a time, until only clear water is present.

General Troubleshooting

Should the Aqua-Hot Hydronic Heating System fail to operate, complete the following checks:

1. Verify that the Aqua-Hot’s access cover is securely installed. The Aqua-Hot will not operate if the access cover is not fully installed.

Note: An interlock switch prevents the Aqua-Hot from operating when the cover is not installed and properly secured in place. Reference page 6 Part #7 for the interlock switch location.

2. Verify that the Aqua-Hot is supplied with electrical power.
3. Make sure there is an adequate supply of diesel fuel (at least ¼ tank).
4. Ensure that the Aqua-Hot boiler tank has an adequate supply of antifreeze and water heating solution by checking the level at the expansion tank. If the level is low, reference the maintenance section of this guide for refilling instructions.
5. Verify the functionality of any in-line fuses connected to the Aqua-Hot. Replace these fuses if necessary.
6. Ensure that all coach-side hot water faucets are closed.
7. Visually inspect the interior of the Aqua-Hot to ensure that there are not any pinched or damaged wires.
8. Locate the high-limit thermostats within the Aqua-Hot. Test these thermostats for functionality, and replace if necessary.
9. Locate and test the control thermostat for functionality. Replace if necessary.
10. Locate and test the fluid circulation pump. Replace if necessary.
11. Locate the three-way valve and test it for functionality. Replace if necessary.

Note: The fluid level sensor is located in the Aqua-Hot’s expansion tank. If the antifreeze solution in the expansion tank drops below the level of the fluid sensor, the Aqua-Hot will not operate.

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 propylene glycol based “boiler” type antifreezes deemed “Generally Recognized As Safe” (GRAS) by the FDA should be utilized.

Due to 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 AquaHot’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 Hot Water Heating Systems.

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 rust inhibitors. Due to their potentially hazardous properties, they should never be used in the Aqua-Hot’s Hydronic Heating System.

Antifreeze Mixture Quality Recommendations

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, deionized, 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 premixed antifreeze are responsible for the use of highquality (distilled, deionized, 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 AquaHot’s boiler tank and associated components prematurely. Therefore, concentrated propylene glycol should be diluted with distilled, deionized, or soft water which is 80ppm or less in total hardness. The local water agency should have up-to-date water quality reports, which should indicate if the local tap water is within this guideline.

Measuring Antifreeze

Measuring Antifreeze Using a Refractometer

Properly Apply

Antifreeze to the Prism Assembly Use the guide below to properly apply the propylene glycol mixture to the prism assembly of the refractometer. Once that is complete, peer through the eyeglass of the refractometer to continue to the next step.

Adjust the Boundary Line

Once the glycol solution has been properly applied, adjust the calibration screw until the boundary line labeled “Propylene Glycol” is set to 32°F. The graphic to the right has been designed as an aid, but note that it may differ from what is shown in the refractometer sight glass.