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Aqua-Hot 125-D02 Service Manual

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Aqua-Hot: 125-D02 Service Manual
This manual contains information related to diagnosis, repair, and maintenance of the Aqua-Hot AHM-125D series of RV
water heating systems.
Download the complete PDF here:
Caution Notes
As you read this information, take particular note of the NOTICE, CAUTION, WARNING, and DANGER symbols when
they appear. This information is important for safe and efficient use of the Aqua-Hot system.
NOTICE signals a situation where potential damage to the Aqua-Hot could occur.
CAUTION signals a situation where potential harm or risk of minor or moderate injury could occur if you do not
follow instructions.
https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho...
AHM-125-D02-Service-Manual
Updated: Wed, 07 Aug 2024 00:30:20 GMT
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Summary of Contents for Aqua-Hot 125-D02

  • Page 1 Aqua-Hot: 125-D02 Service Manual This manual contains information related to diagnosis, repair, and maintenance of the Aqua-Hot AHM-125D series of RV water heating systems. Download the complete PDF here: AHM-125-D02-Service-Manual Caution Notes As you read this information, take particular note of the NOTICE, CAUTION, WARNING, and DANGER symbols when they appear.

  • Page 2: System Overview

    System Overview The Aqua-Hot AHM-125D Series is a Hydronic Heating System that can provide heat and hot water on demand using a built-in electric heating element and an external diesel burner. The Aqua-Hot is a 2-in-1 System https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho…...
  • Page 3 The Aqua-Hot heating system heats an ethylene glycol-based antifreeze (50%) and distilled water solution (50%) that is stored in the Aqua-Hot’s boiler tank. This fluid solution must be up to operating temperature before the Aqua-Hot will provide interior heat or hot water. The tank-less hot water system produces approximately 0.8 GPM of hot water. This system is also hot water priority, so it will shut off the heat any time hot water is called for.
  • Page 4 The Aqua-Hot comes equipped with a three-way valve (some- times known as the summer/winter valve). This controls the flow of the antifreeze and water heating solution within the Aqua-Hot to deliver either hot water or interior heat as priority. Tapping on this element will change the valve’s orientation. When this element is activated, it overrides the automatic function and orients the valve to interior heat.

  • Page 5: Electric Element

    External Diesel Burner The diesel 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 on by tapping BURNER to ON on the LCD screen shown below.
  • Page 6 Aqua-Hot. This service manual is designed to aid trained and qualified technicians to properly service and troubleshoot the Aqua-Hot AHM-125D. Each section in this manual is dedicated to the diagnosis of specific components within the Aqua-Hot which may be inhibiting the operation of the heater.
  • Page 7 If additional assistance is needed in diagnosing and repairing the Aqua-Hot, please contact our Technical Service Department at 574-AIR-XCEL (574-247-9235) from 7:00am to 4:00pm MST Monday through Friday. As With any appliance, allow the aqua-Hot to completely shut down BEFORE disengaging the RV 12V power Disconnect.
  • Page 8 • Disconnect electric wiring to the Aqua-Hot System before welding or plasma cutting the RV to avoid damage to equipment. • The Aqua-Hot tank and heating loop operate at 7.0 PSI. Maximum testing air pressure to the tank must not exceed 18 PSI. Exceeding this rating will cause internal damage to the Aqua-Hot.

  • Page 9: Maintenance Schedule

    Annual Maintenance To maintain the Aqua-Hot at its full potential, it is highly recommended to have the diesel burner tuned up annually. This involves replacing the fuel filter, cleaning the burner, inspecting the exhaust and combustion air lines for damage and ensuring they are clear, checking the fuel lines for any leaks, and checking the hoses and wiring to make sure there are no damage or cracks.

  • Page 10: Overheat Protection

    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.
  • Page 11 In the event of an overheat condition, the high limit thermostat will cut the operating signal to the external diesel burner, and/or the electric element. When this signal is interrupted, the electric element and diesel burner will immediately disengage. Contact Aqua-Hot Heating Systems for assistance in locating a qualified person to service this heater.

  • Page 12: System Features

    System Features 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. Boiler Tank System Specifications https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 13 Electric Element Power Consumption....................................W (maximum) Voltage......................................DC Power Power Consumption ........................................W (maximum) https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 14 Zone Heat Circulation Pumps ........................................Power Consumption (max)..................................1.7A Voltage......................................Interior Heating Maximum Heating Zones......................................Cozy......................................0.5A - 8,000 BTU/hr Whisper....................................... 0.37A - 4,000 BTU/hr H.E. II........................................0.25A - 4,000 BTU/hr NOTE: Control Panel “Quiet Mode” reduces heat exchanger power consumption by 20% Domestic Water Heating Maximum.....................................

  • Page 15: Physical Specifications

    Physical Specifications Dimensions (US)......................................x 7.90”W x 9.66”H Weight......................................Weight......................................All vehicle installations must comply with the requirements listed in the Recreational Vehicle Industry Association’s (RVIA) ANSI/NFPA 1192 Handbook for Recreational Vehicle Standards. Parking Heater System Specifications Diesel Burner Heat Flow......................................

  • Page 16: Operating Temperatures

    Diesel Fuel Consumption....................................to 0.16 gal/hr Coolant Pump ........................................1.7A Operating Pressure (medheat)....................................Flow Rate (minimum)....................................Working Altitude......................................Fuel Fuel Type ........................................Fuel Consumption (Low Output) ........................................0.07g/h Fuel Consumption (High Output) ........................................0.16g/h DC Power Consumption ........................................to 37W Operating Range ........................................
  • Page 17 Burner Operation....................................-40 to 176°F Burner Storage......................................to 248°F Fuel Pump Operation....................................-40 to 86°F Fuel Pump Storage......................................to 194°F Physical Specifications Dimensions....................................8.8”L x 3.4”W x 6.9”H Weight ........................................Technical Specifications Heating Medium Ethylene Glycol/Distilled Water High Power Operation: 5000W Thermal Power (W) Low Power Operation: 2400W Fuel...

  • Page 18: Technical Specifications

    Technical Specifications High Power Operation: 0.16 g/h At Start: <100W Power Consumption (W) High Power Operation: 37W Low Power Operation: 10W Working Pressure (MPa) 0.25 Lowest Working Temperature -40° F / 4.4° C Net Weight (Heater Only) 10.6lbs / 4.8kg Working Height (above Sea Level) 16,405 ft / 5,000 m Weight of Main Heater...
  • Page 19 15. AC Aviation Relay 4. Three-Way Valve Inlet 10. Coolant In 16. Fluid Fill Port w/ Radiator 5. Cozy Heat Exchanger 20. Domestic Hot-Water Aqua-Hot Outlet Controller 6. Burner Circulation Pump 12. LCD Screen Belief Diesel Burner https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT...
  • Page 20 Belief Diesel Burner Diagram Index Combustion Temperature 13. Coolant Pump Sensor Burner Outer 18. Coolant Outlet Casing Pipe 14. Fuse 8. Over-Heat Sensor Burner Inner Coolant Inlet Main Harness 9. Burner Controller Casing Pipe Connector 10. Air Inlet Pipe Combustion 20.

  • Page 21: Operational Flow Chart

    Operational Flow Chart Operating the Aqua-Hot & LCD This section will outline the basic operating instructions for the Aqua-Hot LCD Screen. Climate Pages: https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...

  • Page 22: Zone Control

    The climate pages are for all intents and purposes the “Home” of the LCD screen. From here, the end-user will select their interior temperature set-points, activate or deactivate the diesel burner and/or the electric element. Zone Control Precise zone control display will differ depending on the type of zone thermostats used within the RV. Section 1A demonstrates the appearance of the zone control section when ON/OFF thermostats are used within the RV.
  • Page 23 These arrows are used to increase or decrease the desired set-point temperature of the zone thermistor. Section After the desired temperature set-point has been selected tap “SET” on the LCD to set that temperature. The Aqua-Hot will now work to maintain this interior temperature, and the screen will return home.
  • Page 24 External Diesel Burner Activation The external diesel burner of the Aqua-Hot can be activated by tapping on the “burner” item on-screen. The diesel burner has two modes: ON and OFF. While set to ON, the Aqua-Hot diesel burner will work to maintain a tank temperature of 180° F.

  • Page 25: System Status

    Similar to the external diesel burner, tapping the electric item will signal to the controller to activate the AC electric relay, energizing the 1500W electric element within the Aqua-Hot. The electric element also has two modes: ON and OFF. While set to ON, the electric element will work to maintain a tank temperature of 180°...

  • Page 26: Module Options

    This item will indicate the current operational status of the Aqua-Hot. If any faults have triggered, those will be displayed here. During normal operation, this should display either INTERIOR HEAT or HOT WATER relating to the priority and position of the 3-way valve.
  • Page 27 Tapping on this element will direct you to the Aqua-Hot’s built-in diagnostic, testing, and troubleshooting tools. Quiet Mode This option toggles the Aqua-Hot’s quiet mode. Quiet mode is a setting where the speed and output of the heat exchanger fans is reduced to 80%. This is done to reduce noise of the heat exchangers.
  • Page 28 Electronic Controllers and Relay Control Boards of older Aqua-Hot units. This controller is best utilized with the Aqua-Hot 3.5in display. Using the Aqua-Hot with this new display will ensure that you can take advantage of all of the tools and features of this controller.

  • Page 29: System Voltage

    The new troubleshooting functionality is perhaps the largest and most substantial change to come about from the new controller architecture. Many faults and failures within the Aqua-Hot can now be relayed in plain language to the technician servicing the Aqua-Hot. There are five system faults which will be utilized; System Voltage, Low-Level Cutoff, Over- Current, Overheat, and Burner Failed to Ignite.

  • Page 30: Over-Current

    The Aqua-Hot can only operate within a voltage range of 11V DC to 16V DC. If voltage drops below 11V, or exceeds 16V DC, the controller will shut down the Aqua-Hot as a safety mechanism. Low-Level Cutoff The Low-Level Cutoff fault will only trigger if the minimum fluid level within the Aqua-Hot is below an acceptable operational threshold.

  • Page 31: Operating Mode

    The fault codes shown above will cover the most common Aqua-Hot related issues. For more complex issues, it may be necessary to utilize the DIAG screens, which will be explained next. Diagnostics Screens (DIAG) The diagnostic screens will show the current operational status of different elements within the Aqua-Hot. By comparing these operational statuses against the expected results it is possible to discern operational issues.
  • Page 32 The operating mode contains six items which relay at-a-glance information about the function of the Aqua-Hot. System Voltage: This section of the Operating Mode page indicates the status of the supply voltage to the Aqua-Hot. This will display “OK” if the supply voltage is between 11V DC and 16V DC.
  • Page 33 Inputs from RV The Inputs from RV section will display the signals received from within the RV as pertaining to the RVC network and the heating zone thermostats. With respect to the zones, there will be three different items displayed next to the Zone # items depending on the type of RV-side thermostat in use.
  • Page 34 Inputs from Aqua-Hot The Inputs to Aqua-Hot will contain the current readings from sensors within the Aqua-Hot. Four elements will be shown on this page; Burner Status, LTCO Status, LLCO Status, and Tank Temperature.

  • Page 35: Tank Temperature

    The Tank Temperature status will display the current temperature of the antifreeze and water heating solution within the Aqua-Hot. The ETS Thermistor (short for engine temperature sensor) provides the temperature reading to the controller to determine when the external diesel burner and/or electric element shut off.
  • Page 36 Hot for testing purposes. This will allow a technician to activate specific elements within the Aqua-Hot as needed without jumping wires or utilizing external power supplies in most troubleshooting cases. Any elements activated via the testing screen will remain active for a maximum of five minutes.
  • Page 37 All three zone fans can be activated as needed to test communication between the zone fans and the controller. Please note that this will only work if the zones have been directly wired to the Aqua-Hot as described in the installation manual.
  • Page 38 Activating the Electric heating sub-system will energize the relay which controls the AC electric element. After tapping this button on the screen, there should be an audible click from within the Aqua-Hot boiler tank. If there is no such click, verify the functionality of the AC electric relay.
  • Page 39 Three-Way Valve The final element on this screen is not directly related to the heating subsystems of the Aqua-Hot. The three-way valve (sometimes known as the summer/winter valve) controls the flow of the antifreeze and water heating solution within the Aqua-Hot to deliver either hot water, or interior heat as requested. Tapping on this element will change the valve’s orientation.
  • Page 40 • Tap OPTIONS, CLIMATE ZONES, and take a picture of the following screen. 2. Disconnect all power to the Aqua-Hot. 3. Remove the plugs from the controller and disconnect the DC harness from the controller. 4. Unscrew the four screws attaching the sheet metal cover/housing to the wall, and remove the defective controller.
  • Page 41 5. Install the replacement controller using the 4 screws previously removed. 6. Carefully reinstall all of the plugs from the DC harness. • Ensure that both tabs for all Molex connectors click into place indicating a properly seated connection. • Ensure that the single tab for the RVC cable clicks into place indicating a properly seated connection. NOTE: All plugs have only ONE correct orientation.
  • Page 42 After replacement and installation of the controller, the system will need to be updated via the LCD Screen or RV Control panel. 1. Provide power to the main harness of the Aqua-Hot. After the screen lights up, tap the three lines icon on the bottom right corner.

  • Page 43: Float Switch

    The float switch monitors the fluid level within the Aqua-Hot. This device is intended as a fail-safe measure which will disengage the Aqua-Hot if the fluid ever drops below a set threshold. The float switch is located on the boiler tank face behind the AC cover.

  • Page 44: Troubleshooting Procedure

    • Ensure that DC electrical power is supplied to the Aqua-Hot. • Ensure that AC electrical power is supplied to the Aqua-Hot’s electric element. If any of the requirements above are not fulfilled, correct them before continuing to diagnose the float switch. Reference the troubleshooting guide below.
  • Page 45 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 46 Replacement Procedure Before Continuing to the replacement procedure, ensure that the unit has cooled to ambient temperature, all power sources have been disconnected, and the unit is completely shut off. In order to replace the float switch, a float switch kit with the switch and the quick disconnect terminal must be ordered. Please visit www.aquahot.com or call 574-AIR-XCEL (574 247-9235) to order the kit (part number ELX-135-M01).
  • Page 47 5. Disconnect the Faston connectors, remove the defunct float switch, and discard the switch. 6. Secure the new switch in position. 7. Crimp the new faston connectors to the new float switch. 8. Connect these wires to their receptacles on the Aqua-Hot harness. 9. Reconnect the hose to the lower fitting. https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho…...

  • Page 48: High Limit Thermostat

    574-AIRXCEL (574-247-9235) from 7:00am to 4:00pm MST Monday through Friday. High-Limit Thermostat The Aqua-Hot is equipped with a resettable High-Limit Thermostat. This thermostat is in place to prevent the heater from operating beyond its safe operational threshold. This thermostat is resettable and easily replaceable.
  • Page 49 • Verify that all in-line fuses are functional. • Ensure that the unit is completely cool. • Ensure that DC electrical power is supplied to the Aqua-Hot. • Ensure that AC electrical power is supplied to the Aqua- Hot’s electric element.

  • Page 50: Replacement Procedure

    Replacement Procedure If it has been determined that the high-limit thermostat needs to be replaced, it can be easily replaced by following the https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 51 1. Disconnect all sources of AC and DC power from the Aqua-Hot (the AC access cover will need to be removed - see Figure 36). 2. Disconnect the wires which connect to the non-functional high-limit thermostat. 3. Using a ⅝” (16mm) wrench, remove the thermostat from its location on the boiler tank.

  • Page 52: Low-Temperature Cutoff Thermostat

    The Low-Temperature Cutoff Thermostat (LTCO) is installed to measure the incoming domestic water temperature. Using that reading, the Aqua-Hot controller is able to determine whether a demand for hot water exists or not. This thermostat should be diagnosed if there is a lack of interior heat or hot water and the tank is up to operating temperature.
  • Page 53 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 54 Replacing the Low-Temperature Cutoff Thermostat 1. Disconnect all sources of AC and DC power from the Aqua- 2. Disconnect the wires from the LTCO. https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 55 3. Remove and discard the defunct LTCO thermostat using a 3/16” socket. 4. Position and secure the new LTCO thermostat into place. 5. Connect wires J4-1 and J4-2 to the new LTCO thermostat. Three-Way Valve The three-way valve (aka the summer/winter valve) is responsible for changing the flow of coolant either through the interior heating zone (int heat) or circulating coolant within the boiler tank (hot water mode) to prioritize hot water.
  • Page 56 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 57 Before replacing the 3-way valve, you must purchase the repair kit. The Repair Kit should include: • Three-Way Valve • Black Nylon elbow adapter • Black Nylon barb adapter • 2-pin electrical connector https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 58 Replacement Procedure 1. Drain coolant from system. • Pour into a bucket to be reused later 2. Locate the Three-Way Valve. Clamp off the hoses at the three-way valve: 3. Disconnect the electrical connection from the Three-Way Valve to the DC harness. 4.
  • Page 59 6. Install the new three-way valve and then reinstall the hoses on the new valve. Ensure that the orientation of the valve remains the same. 7. Tighten the hose clamps and reconnect the wire harness to the valve. 8. Refill the unit with the coolant saved from Step 1. •...

  • Page 60: Tempering Valve

    Tempering Valve Introduction The tempering valve of the Aqua-Hot mixes the hot domestic water from the Aqua-Hot with cold incoming domestic water to mix it to a threshold where scalding will not occur. https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT...
  • Page 61 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 62 Do NOT attempt to adjust the tempering valve without assistance from Aqua-Hot Technical Support or a qualified Aqua- Hot technician. NOTE: The Aqua-Hot Domestic Water System is rated for a water flow of 0.8 GPM. It is not recommended to modify the water flow. This can cause a lack of consistent hot water.

  • Page 63: Testing Procedure

    Testing Procedure Follow the testing procedure to the right in order to diagnose the tempering valve. Troubleshoot the tempering valve if the following conditions have occurred: • A lack of hot water. • Hot water supply is uneven. • Hot water is too hot. https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho…...
  • Page 64 Replacement Procedure 1. Shut off the external domestic water connection and open a hot water faucet valve within the RV to relieve the water pressure. 2. Open the RV domestic water drain valve and release water https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 65 from the system. 3. Disconnect the RV side domestic water connections 4. Locate the tempering valve assembly within the RV. 5. Remove the fasteners that secure the tempering valve assembly. 6. Disconnect the water lines from the brass fittings on the tempering valve assembly. •...
  • Page 66 9. Using Teflon tape and domestic water safe thread sealant, reinstall all fittings on the new valve to previous orientations. 10. Place previous P-clamp onto the assembly before inserting into the Aqua-Hot. 11. Connect the water lines to the tempering valve assembly ensuring they are plumbed to the same place they were removed from.
  • Page 67 12. Reusing the fasteners and P-clamps, reattach the tempering valve assembly to the vehicle. Tank Fluid Circulation Pump Introduction The fluid circulation pump operates to provide fluid circulation to either the interior heating zone or the antifreeze boiler tank depending on the heating and hot water needs at the time. Troubleshooting Procedure If the fluid circulation pump has failed, it will typically indicate an over-current fault on the controller fault log.
  • Page 68 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 69 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 70 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 71 Replacement Procedure 1. Place a paper towel on the bottom of the cabinet. (This is to help absorb any residual coolant left in the lines upon pump removal.) 2. Drain coolant from the lower tank fitting (see Figure 53). Pour into a bucket to be reused later. 3.
  • Page 72 • Monitor the newly installed parts and fittings for leaks. AC Electric System The AC Electric system of the Aqua-Hot AHM-125D unit functions to provide heat to the Aqua-Hot boiler tank. This is done with an electric element and an electric relay.
  • Page 73 • Verify that all in-line fuses are functional. • Ensure that the unit is completely cool. • Ensure that DC electrical power is supplied to the Aqua-Hot. • Ensure that AC electrical power is supplied to the element. • Verify the thermostats are in working order.
  • Page 74 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 75 1. Ensure that the Aqua-Hot has been completely shut down and all power sources have been disconnected. Be sure the boiler tank is completely cooled. 2. Drain the antifreeze and water solution from the Aqua-Hot’s boiler tank from the lower tank fitting. Drain the coolant into an external container to be reused.
  • Page 76 8. Reconnect the wires previously disconnected from the electric heating element and tighten the screw terminals, then put the AC cover back on. 9. Refill the Aqua-Hot boiler tank with the previously drained fluid, add more 50/50 mix of ethylene glycol and distilled water to the tank if needed.
  • Page 77 • Verify that all in-line fuses are functional. • Ensure that the unit is completely cool. • Ensure that DC electrical power is supplied to the Aqua-Hot. • Ensure that AC electrical power is supplied to the Aqua- Hot’s electric element.
  • Page 78 Replacement Procedure 1. Ensure that the Aqua-Hot has been completely shut down and all power sources have been disconnected. Be sure the boiler tank is completely cooled. 2. Ensure that the RV is not connected to shore power and that a generator is not connected during this procedure.
  • Page 79 The ETS (Engine Temperature Sensor) Module is a brass thermistor that continually measures the temperature of the fluid within the Aqua-Hot boiler tank. This module then relays the information to the Aqua-Hot controller, thereby allowing the controller to activate and deactivate the unit as heating and hot water needs change.
  • Page 80 Verify the following before proceeding with the troubleshooting: • The boiler tank is adequately filled. • Ensure that DC electrical power is supplied to the Aqua-Hot. • Ensure that AC electrical power is supplied to the Aqua- Hot’s electric element.
  • Page 81 Replacement Procedure https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 82 10. Pour the previously removed fluid back into the tank and allow it to fill the system. 11. Once this has been completed, locate the Aqua-Hot LCD screen, navigate to the test section, and run the fluid circulation pump (and if applicable the boost pump) for at least twenty minutes to purge the heating loop of air.

  • Page 83: Fuel System

    12. Continually fill the tank as the fluid level drops. 13. Test the Aqua-Hot for normal operation. Fuel System NOTE: The diagram above is not drawn to scale. It is simply a reference for proper installation of the fuel system for the Belief Diesel Burner.

  • Page 84: Fuel Filter

    Fuel System Plumbing • Ensure the fuel system meets the requirements detailed in Figure 65. • Ensure no connections leak. Any leaking connections will lead to burner problems. • Where possible, the fuel line should have a gentle incline from the fuel tank to the burner. Fuel line should be installed as flatly as possible, avoiding sharp rises and falls.
  • Page 85 Please follow instructions to ensure safe operation. Always check for any fuel leaks before operating the burner. https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 86 https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 87 Fuel System Fill Procedure Perform this procedure after any fuel components have been serviced and/or replaced. • Ensure all fuel system connections have been made. • Ensure all fuel line clamps are tight. • The fuel level in the vehicle’s tank must be above the fuel pickup level. •...
  • Page 88 • If a different fault is displayed, follow the trouble shooting guide on page 40 and address the cause of the fault. External Diesel Burner Troubleshooting The troubleshooting procedures listed below are arranged in order of repair complexity. Do not replace parts without correctly determining the failure.

  • Page 89: Heater Lock-Out Reset Procedure

    Triggering Overheating Fault If there is an overheat fault, the overheat failure is generally caused by the temperature in the Aqua-Hot. A lack of antifreeze/distilled water solution may cause overheating failures, because the Aqua-Hot temperature cannot be carried away by the antifreeze/distilled water solution.
  • Page 90 The burner lockout reset must be done manually as shown below. Troubleshooting Procedure • Turn on the burner, on the interior control panel. • Remove the main power connection to the burner or pull the fuse for a minimum of 20 seconds. •...
  • Page 91 Fault Fault Cause Remedy Code Burner: Heat Plug Failure Poor/Reduced Performance • Replace glow plug • Replace controller Burner: Heat Plug Failure Heat Plug Voltage not detected Burner: Fan Speed too high • Replace burner controller Burner: Fan absent/broke circuit •...
  • Page 92 Fault Fault Cause Remedy Code Burner: Temperature sensor absent/broken circuit • Check temperature sensor (normal Burner: Temperature sensor short-circuit temperature resistance about 10 Ω) • Replaced temperature sensor Burner: Coolant temperature is too high prior to ignition Burner: Flame sensor absent/broken circuit •...

  • Page 93: Servicing The Burner

    This section covers the typical failures of the diesel burner. Refer to the following table for additional failures and their remedies. Failure Symptom Possible Cause Remedy No combustion after start or Switch off burner and switch back on automatic repeat start •...
  • Page 94 Please follow instructions carefully. The first operation of the burner (after service or maintenance) with the Aqua-Hot may not light up perfectly. It may take 5-6 starts for the burner to ignite for the first start-up after service, because the fuel pump needs to fill the fuel lines leading to the burner for ignition.
  • Page 95 3. Listen for burner ignition, it can take around 1 minute to ignite. 4. Tap the three lines icon -> Diagnostics -> Diagnostics -> Next 5. Locate the "Tank Thermistor" field https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...

  • Page 96: General Troubleshooting

    6. Watch for the "Tank Thermistor" temperature to increase 2 to 3 degrees. • If no temperature increase is seen diagnose the burner following the service manual. 7. Allow the burner to heat the tank to full temperature (180°F). 8. Tap the Home icon -> Back -> Burner to OFF. Note: It is recommended to run the burner for at least 20 minutes every month to ensure optimum heater condition Note: Both the electric heating element and the external diesel burner are thermostatically controlled.
  • Page 97 2. Make sure there is an adequate supply of diesel (at least 1/4 tank). 3. Ensure that the Aqua-Hot boiler tank has an adequate supply of antifreeze and water heating solution by checking the level at the boiler tank. If the level is low, reference the maintenance section of this guide for refilling instructions.
  • Page 98 9. Locate and test the fluid circulation pump. Replace if necessary. 10. Locate the three-way valve and test it for functionality. Replace if necessary. 11. Make sure there are no faults displayed on the LCD screen as shown to the right. https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho…...
  • Page 99 NOTE: The float switch is located on the Aqua-Hot's boiler tank, as shown in figure 79. If the antifreeze solution in the tank drops below the level of the float switch, the Aqua-Hot will not operate. Winterizing the Aqua-Hot Not winterizing the Aqua-Hot when freezing temperatures are present will https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho…...
  • Page 100 Please follow these instructions when winterizing the Aqua-Hot domestic water heating system. NOTE: The Aqua-Hot can continue to be used for interior heat once the domestic hot water system has been winterized. 1. Completely drain the fresh water storage tank.
  • Page 101 Using products containing bleach, including water refreshers, may cause corrosion of the domestic water lines, resulting in a catastrophic failure of the Aqua-Hot system by creating leaks that cannot be repaired. This damage is not covered by the Aqua-Hot warranty.
  • Page 102 Zone Heat Exchangers & Zone Thermostats https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 103 External Diesel Burner https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 104 Sensors, Thermostats, & Electric Element Parts NOTE: For more parts & information, please reference the AHM-125-DO2 Parts manual found online at https://www.aquahot.com/library/aspx. https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 105 Thermistor, Tank Temperature Sensor Thermistor, 10K NTC, Room Temperature Sensor Purchase at Tiffin Motorhomes Here RV-Side Wire Harness (optional) Aqua-Hot LCD, Screen, RVC 3.5in Aqua-Hot Series 125 Mainframe Harness https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 106 RVC Display Cable Low-Temperature Cutoff Thermostat with Spade VAC High Limit Thermostat 215°F with Leads Terminals 1500W, 120 VAC Electric Element, 1" NPSM Controller, 12VDC, 100-200 Series, Kit Purchase at Tiffin Motorhomes Here https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 107 Float Switch Kit, 1/2" NPT with Quick Disconnect Heat Exchanger, Cozy III Terminal Purchase at Tiffin Motorhomes Here Purchase at Tiffin Motorhomes Here Fluid Circulation Pump Small Heat Exchanger, (2) 1/2" FNPT, (2) 2" MNPT Purchase at Tiffin Motorhomes Here https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho…...
  • Page 108 Pressure Relief Valve, 125 PSI Harness, Buehler C20 Pump Purhase at Tiffin Motorhome Here Tempering Valve Kit, Three-Way Motorized Valve, 1/2" NPT Purchase at Tiffin Motorhomes Here Purchase at Tiffin Motorhomes Here https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 109 AC Relay, 30A 277VAC Cover, AC Element Cover for 125 Series Hose, 3/4" Safety Stripe, Rubber Assembled Fuel Pump Refractometer Belief 5kW Diesel Burner Circulation Pump https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 110 Fuel Hose to Burner Fuel Hose to Fuel Tank (Blue) Clamp, (10.5mm), Soft Hose and Tube Clamp, 3/8 to 7/16 (11.3mm), Soft Hose and Tube Burner K_Line Converter Burner Wiring Harness https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...
  • Page 111 Measuring Antifreeze Using a Refractometer Properly Apply Antifreeze to the Prism Assembly Use the guide below to properly apply the ethylene 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 “Ethylene Glycol”...
  • Page 112 ©2022 Aqua-Hot Heating Systems, LLC. Printed in the USA https://tiffin-motor-homes-prod.mindtouch.us/Resources/All_Component_Manuals/Water_Heaters%2F%2FPlumbing/Aqua-Ho… Updated: Wed, 07 Aug 2024 00:30:20 GMT Powered by...

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