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2-YEAR LIMITED WARRANTY AQUA-HOT® 
HYDRONIC HEATING SYSTEM

Aqua-Hot Heating Systems Inc. warrants the Aqua-Hot Heater to be free from defects in 

material and workmanship under normal use and service for a period of two years on 

both parts and labor commencing upon the original date of registration of the vehicle. 

Replacement parts are warranted for the remainder of the Heater’s standard warranty 

coverage or for six months, whichever is greater. The intent of this warranty is to protect 

the heater’s end-user from such defects, which would occur in the manufacturing of the 

product. Thus,  problems due to  improper specifications,  improper installations, improper 

use, the use of accessory parts or parts not authorized by Aqua-Hot Heating Systems Inc., 

repair by unauthorized persons, and damage or abuse of the heater are specially excluded 

from warranty coverage.
For additional information, or to obtain a warranty repair authorization, please contact the 

Aqua-Hot Heating Systems Warranty Administrator at 1-800-685-4298 (7:00 AM to 4:00 PM 

Mountain Standard Time) or visit www.aquahot.com.

My Comfort Zones are On-Board

 

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Dealer Information: 

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Heating System:

 

Serial Number:

Warranty

Summary of Contents for Aqua-Hot 200 Series

Page 1: ...Service Manual 200Series AHE 250 D03...

Page 2: ...ce 78 Cold Weather Operation 90 Fill and Purge Procedure 91 Winterization 92 General Troubleshooting 93 Lack of Hot Water 93 Lack of Heat 94 Blue White Smoke 95 Black Smoke 95 Caution Notes As you rea...

Page 3: ...to the Aqua Hot 250 D03 Service Manual This manual will serve as a guide for diagnosing and repairing the Aqua Hot how to perform standard maintenance and guide you through troubleshooting procedures...

Page 4: ...GRAS by the FDA must be utilized for the antifreeze and water heating solution An interlock switch prevents the Aqua Hot heater from operating when the cover is not installed in the correct position D...

Page 5: ...ion 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 When...

Page 6: ...1 Domestic Water Heating Maximum 1 5 GPM Physical Specifications Dimensions US 26 L x 12 46 W x 17 2 H Dry Weight 84lbs Wet Weight 104lbs All vehicle installations must comply with the requirements l...

Page 7: ...9 Domestic Cold Water Inlet 10 Domestic Hot Water Outlet 11 120V AC Connection 12 Diesel Fuel Return Port 13 Diesel Fuel Supply Port 14 Expansion Tank Connection 15 Heating Zone Return Port 16 Heating...

Page 8: ...o 180 F An Interior Zone Thermostat Calls for Heat A hot water faucet opens signaling a need for heat to the boiler tank The fluid circulation pump activates and begins circulating the heated antifree...

Page 9: ...nstalled Thermostats would only show ON OFF If the zone temperature is set but this item is not set to ON the zone heat exchanger will not activate Section B These arrows are used to increase or decre...

Page 10: ...y valve is oriented so that the heated antifreeze and water solution is circulated immediately back into the boiler tank This is known as stirring the tank and it is done to provide as much heat as po...

Page 11: ...Aqua Hot 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 Lev...

Page 12: ...his status indicates that the controller is attempting to activate the element relay only This does NOT indicate whether the electric element is in working order or not Heat Zone The next three elemen...

Page 13: ...ot The ETS Thermistor short for engine temperature sensor provides this temperature information to the controller which then governs when the diesel burner and or electric element shut off Outputs to...

Page 14: ...w features of this control system is the ability to independently activate specific elements within the Aqua Hot for testing purposes This will allow a technician to activate specific elements within...

Page 15: ...olex bottom of the controller NOTE DO NOT DISCONNECT THE DC HARNESS FROM ANY OTHER ELECTRICAL CONNECTION IN THE UNIT 9 Pin Molex 12 Pin Molex RVC 8 Pin Molex 15 Pin Molex Figure 17 Controller Replacem...

Page 16: ...e controller and mounting plate into the Aqua Hot the mounting plate should slide along the wall to ensure the key ways catch the mounting studs Figure 18 12 Once the controller and mounting plate are...

Page 17: ...and hold for 3 seconds within the Aqua Hot Information section Tap SERIAL NUMBER and follow the prompts on the screen 2 On the Diagnostics page tap and hold for 3 seconds in the Aqua Hot Information...

Page 18: ...eath an openable window or vent in the awning area of the RV if applicable or near the slide out areas The exhaust must be able to freely exit away from the vehicle without any obstructions Use standa...

Page 19: ...nel 3 Locate wires 12 and 24 on the wiring harness as they lead into the interlock switch 4 Disconnect the wires from the switch noting that wire 24 is connected to the terminal labeled NO and 12 is c...

Page 20: ...on The fluid level sensor monitors the current 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 thre...

Page 21: ...g of the expansion bottle 5 Remove the hose and allow the excess fluid to drain into the bucket 6 Remove the overflow hose from the upper fitting of the expansion bottle 7 Remove the old expansion bot...

Page 22: ...cess cover is properly installed The overflow bottle 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 elec...

Page 23: ...module from the Aqua Hot s boiler tank 6 Wrap the threads of the replacement ETS module with 6 wraps of thread seal tape 7 Place the replacement ETS module in its position on the tank face and finger...

Page 24: ...bleshooting procedure cannot be verified if the conditions listed above are not fulfilled Troubleshooting Procedure 1 Verify the following before troubleshooting the AC high limit thermostat The ETS m...

Page 25: ...ble to the body of the thermostat and strip the other end 7 Remove the faulty high limit thermostat using a socket or crow s foot 8 Butt splice a new AC high limit thermostat to the stripped wire 9 Re...

Page 26: ...Burner High Limit Thermostats Introduction The burner high limit thermostats serve as a safety measure in the event that the burner continues to operate after the maximum operating temperature 215 F h...

Page 27: ...fying that the LCD screen shows the LTCO status properly Verify that the Aqua Hot is at operating temperature between 155 F and 185 F by using a meat thermometer secured to the tank face Verify that d...

Page 28: ...y separating the quick disconnect terminals 4 Using a wrench or crow s foot wrench remove the defective LTCO thermostat from the Aqua Hot 5 Install the replacement LTCO torquing it to 15 in lbs ONLY A...

Page 29: ...l be a supply when heated water is being called for but can provide interior heating when the need arises Troubleshooting Condition Troubleshoot the three way valve if the following conditions have oc...

Page 30: ...ubing surrounding the three way valve as indicated in Figure 48 3 Remove the valve wires from the green connector plugged into the controller 4 Using constant tension pliers loosen and slide back the...

Page 31: ...sting the mixing valve results in no change it may be a faulty mixing valve 7 If adjustment of the mixing valve is able to effect change in temperature it must be continually adjusted until the output...

Page 32: ...ing Procedure Follow the procedure to diagnose the fluid circulation pump 1 Verify the following before troubleshooting the circulation and stir pump The ETS module is calling for heat The interlock s...

Page 33: ...pliers loosen and slide back the constant tension clamps securing the hoses to the circulation pump 6 Remove the hoses from the defective circulation pump 7 Set the defective pump aside and put the re...

Page 34: ...hore power or an AC generator 4 Using an infrared thermometer take the temperature of the tank face The thermometer should be 12 away from the tank face and set to high emissivity Record this temperat...

Page 35: ...hanger lines to remove any and all air from the system by running the fluid circulation pump for 20 minutes Failure to disconnect all power supplies and or allow the unit to cool before servicing coul...

Page 36: ...shooting Results of the troubleshooting procedure cannot be verified if the conditions above are not fulfilled 1 Locate the AC wires connected to the AC relay and remove the wires from the relay 2 Usi...

Page 37: ...mbustion reaction into the antifreeze and distilled water heating solution present in the Aqua Hot s boiler tank which is distributed to heat exchangers or to the domestic hot water coil to provide ho...

Page 38: ...Fluid Circulation Pump Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 38 Diesel Burner...

Page 39: ...ition Wire Elbow 10 WPX 350 427 Combustion Air Intake Shutter 11 WPX 432 377 Protection Housing Screw 12 WPX 152 269 Washer Star Protection Housing 14 WPX 436 216 Protection Cap 22 WPX 147 834 Screw F...

Page 40: ...er Lock Blower Casing 40 WPX 301 841 Blower Housing 41 WPX 373 001 Blower Wheel with Shaft 42 WPX 378 313 Bearing Kit 43 WPX 412 244 O Ring Blower Casing 44 WPX 225 67A Blower Casing 45 WPX 298 964 Gr...

Page 41: ...560 Washer Lock Electrode 54 WPX 278 971 Electrode Clamp 55 WPX 274 313 Ignition Electrode 56 WPX 638 78A Flame Sensor 57 WPX 887 71A Photo Disc 58 WPX 453 048 Clip Retaining Photo Disc 59 WPX 147 69...

Page 42: ...e 67 WPX 277 282 Fuel Pump Mounting Screw 68 WPX 152 544 Washer Lock Fuel Pump 69 WPX 886 41A Fuel Nozzle 0 35 GPH 70 WPX 412 198 Manifold Fuel Nozzle Brass 71 WPX 277 150 Screw Plate Nozzle Stand 72...

Page 43: ...occurs The ETS Module which senses coolant temperature reaches the preset temperature of approximately 190 F The Aqua Hot s diesel burner is turned OFF Once the heater switches to OFF thermostatically...

Page 44: ...irculation Pump Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 44 NOTE The Motor and Combustion Air Blower will begin to operate only if the ETS Module is calling for heat Diesel Burner Op...

Page 45: ...Fluid Circulation Pump Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 45 Diesel Burner Operation...

Page 46: ...n the coolant temperature in the Aqua Hot s Boiler Tank reaches 190 F 5 Once the Diesel Burner has switched OFF the Motor and Combustion Air Blower will continue to operate for approximately 2 3 minut...

Page 47: ...disconnect power could result in serious bodily injury Be sure to clamp off the Fuel Supply and Return lines at the ports on top of the Aqua Hot prior to beginning this replacement procedure Instructi...

Page 48: ...4 Remove the fuel lines from the Aqua Hot 1 Locate where the fuel lines on the diesel burner connect to the Aqua Hot bulkhead fittings 2 Using a 7 16 wrench loosen the nuts securing each fuel line to...

Page 49: ...Burner from the Aqua Hot The diesel burner is secured to the Aqua Hot with two nuts that can be loosened and swung out of the way by using a 10mm socket wrench with a 10 long extension Figure 71 Figur...

Page 50: ...e 20 40 in Lb An improper alignment or over tightening of the eye bolt nuts can cause damage to the burner s cast aluminum blower casing Step 1 Reattach the Diesel Burner to the Aqua Hot The diesel bu...

Page 51: ...the diesel burner or serious damage will occur to the diesel burner s fuel pump Step 3 Reconnect the Controller and Mount Locate the diesel burner s Controller and connect both plugs that were previo...

Page 52: ...Access Cover Reinstall the Aqua Hot s access cover and securely tighten the three bolts securing the access cover in place NOTE The access cover must be installed prior to operation as a safety switc...

Page 53: ...is not 12V DC present on the C 2 pin continue with the troubleshooting procedure 2 Verify the controller is sending power to the diesel burner motor Using a voltmeter check for 12V DC on the controll...

Page 54: ...and brown wires 7 Connect the motor s wires directly to a 12V DC power supply 8 Turn the power supply ON and use a photo tachometer to test for a proper RPM reading 9 At approximately 12V DC the RPM...

Page 55: ...the motor flange pointing upward This will ensure a proper protection cap fit 6 Reinstall a clutch half on both the new motor s shaft and the combustion air blower shaft Attach the motor and flange as...

Page 56: ...Fluid Circulation Pump Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 56 Burner Components Protection Housing Blower Housing Blower Casing Motor Flange Figure 92 Electrode Adjustment Gauge...

Page 57: ...ach and reattach the diesel burner head Be sure to review the detaching reattaching procedure starting on Page 47 3 Connect the flame sensor s green and blue wires to an ohmmeter 4 Check resistance by...

Page 58: ...m the C plug harness green and violet wires Remove the defective 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 4 Conn...

Page 59: ...eview the detaching reattaching procedure starting on Page 47 Ignition Electrode Adjustment Procedure 1 Follow the directions for detaching reattaching the diesel burner on Page 47 2 Using a 10mm sock...

Page 60: ...he electrode in place 6 Slide the electrode into the photo disc 7 Install retaining clamp and retaining clamp bolt and finger tighten 8 Follow the ignition electrode adjustment procedure to properly a...

Page 61: ...ls are intermittent and will need to be tested numerously If the ignition coil tests well and it still will not operate it is possible there is an issue with the Reporter Replacement Procedure 1 Disco...

Page 62: ...w the detaching reattaching procedure starting on Page 47 3 Remove both the ignition cables from the ignition electrodes or connect a jumper wire with alligator clips across the metal tips of the elec...

Page 63: ...placing the fuel nozzle be sure to tighten the nozzle loosen it a turn and then firmly re tighten This will establish a seated fit and avoid any leaks 3 After replacing the fuel nozzle reattach the di...

Page 64: ...onnect the C plug harness violet and brown wires from the fuel solenoid 2 Using a 8mm wrench remove the lock nut and flat washer from the end of the fuel solenoid shaft and then pull the fuel solenoid...

Page 65: ...al source inspect the following in the RV Check the motor home fuel tank for diesel fuel If the fuel level is below the Aqua Hot diesel burner will not operate Inspect the supply fuel line for any kin...

Page 66: ...reattaching the diesel burner Fuel Supply Banjo Tube Fuel Return Banjo Tube Fuel Solenoid Fuel Pump Photo Disc Figure 108 Burner Components nozzle stand and the ignition electrodes 3 Loosen the suppl...

Page 67: ...etaining Clip Photo Disc 61 Photo Disc 62 Fuel Pump 65 High Pressure Fuel Tube 66 Banjo Bolt 67 Gasket Ring Copper 68 Banjo Fuel Tube Supply 69 Banjo Fuel Tube Return 70 Mounting Screw Fuel Pump 71 Wa...

Page 68: ...otor 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 fo...

Page 69: ...n 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 a...

Page 70: ...the diesel burner head 18 Follow the instructions for reattaching the diesel burner in the detaching reattaching section in this manual NOTE Inspect the clutch halves for cracks and ensure the flat po...

Page 71: ...ding does not register on the voltmeter the controller must be replaced If voltage is present proceed to the next test ETS Module Circuit Test Locate the diesel burner controller s B plug and C plug I...

Page 72: ...ust be replaced If voltage is present proceed to the next circuit test Ignition Coil Circuit Test Turn the diesel burner OFF and locate the diesel burner controller s C plug Also locate the VDC high l...

Page 73: ...s pressure setting The fuel pump is preset to 145 PSI Perform the following procedure to check for a proper fuel pressure setting Step 2 Install the fuel line bypass fittings onto the diesel burner 1...

Page 74: ...Hot 250 D03 Diesel Series Service Manual REV 220302 p 74 Step 3 Install the fuel pressure gauge 1 Using a and wrench remove the fuel nozzle Figure 121 2 Using a and wrench install the fuel pressure ga...

Page 75: ...ter the diesel burner has been activated DO NOT attempt to make any fuel pressure adjustments until the spark has disappeared Failure to do so may result in serious bodily injury In some installments...

Page 76: ...odes for a brief moment after the diesel burner has been activated DO NOT attempt to make any fuel pressure adjustments until the spark has disappeared Failure to do so may result in serious bodily in...

Page 77: ...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 NOTE If the fue...

Page 78: ...Hot Fluid Line Cold Fluid Line Fill Cap Lower Fitting Upper Fitting Figure 128 Failure to disconnect all power supplies and or to allow the heater to cool before servicing could cause serious damage...

Page 79: ...th the proper replacement canister 4 Remove the hose pinch off pliers Step 3 Run the Diesel Burner 1 Turn the diesel burner ON 2 After the diesel burner has ignited let it burn for 1 2 minutes to purg...

Page 80: ...esel burner is secured to the Aqua Hot with two nuts that can be loosened and swung out of the way by using a 10mm socket wrench with a 10 inch long extension Be sure to clamp off the fuel supply and...

Page 81: ...transfer tabs to loosen soot deposits Failure to do so will reduce the Aqua Hot s heat transfer capabilities NOTE To remove the diesel burner it maybe necessary to disconnect the ETS Module and High L...

Page 82: ...s Burner Maintenance Failure to reinstall the combustion chamber will result in serious damage to the diesel burner Outer ring that the photo disc seats against Back side of air swirler Step 6 Reinsta...

Page 83: ...uel Pump Fuel Nozzle Electrodes Grommets Inspect the following 1 Electrodes Damaged Improperly adjusted 2 Fuel Pump Leaks 3 Photo Disc Warped Bent 4 Harness Ignition Coil Wires Cracked or bare wires H...

Page 84: ...away any carbon deposits that may have baked onto the metal tips of the ignition electrodes with a coarse sponge 2 Flame Sensor For light dirt dust and or carbon deposits simply wipe off the flame se...

Page 85: ...seated fit and avoid any leaks Wrench Wrench NOTE Be sure to use care when handling the new fuel nozzle Oils and or small dust or dirt particles from your hands may plug the nozzle s small orifice A p...

Page 86: ...lamp bolt when readjusting the ignition electrodes Over tightening the retaining clamp bolt will bend the retaining clamp and prevent the photo disc from floating freely Not allowing the photo disc to...

Page 87: ...ning clamp returns to proper form Step 12 Reinstall the Diesel Burner 1 Align the diesel burner with the Aqua Hot using the alignment tabs welded on the Aqua Hot 2 Swing the eye bolts around the Ears...

Page 88: ...will occur to the diesel burner s fuel pump Step 14 Plug in the Diesel Burner s Controller and Mount 1 Locate the diesel burner s controller and connect both plugs Figure 153 Figure 154 NOTE The diese...

Page 89: ...til it shuts off on its own 2 After the diesel burner has shut off turn on the interior heat or run hot water until the diesel burner cycles back on When the diesel burner cycles back on check the exh...

Page 90: ...ation NOTE The Aqua Hot can continue to be used for interior zone heating once the domestic water heating system has been drained and winterized Diesel Burner If the Diesel Burner fails to operate Det...

Page 91: ...at any air in the heating loop has been purged If necessary top off the propylene glycol solution at the fluid expansion bottle Filling and Purging the Aqua Hot 250 D03 Before the first activation of...

Page 92: ...ONLY antifreeze is exiting the faucets in the RV 7 Once this has been completed deactivate and disconnect the external fluid pump 8 Close all but one faucet in the RV This will allow the winterization...

Page 93: ...and follow the procedure on Page 26 to troubleshoot these components Visually inspect the exhaust system of the Aqua Hot to ensure that it has not been damaged or removed Test for unit operation If t...

Page 94: ...D03 contains a 20A fuse in the wiring harness Make sure this fuse has not burned out Make sure the high limit thermostats are not tripped or defective Replace if necessary Test for unit operation If...

Page 95: ...is possible that the electrodes of the igniter module have been knocked out of adjustment 2 Follow the directions on Page 47 to gain access to the diesel burner head 3 Using a Webasto electrode gauge...

Page 96: ...sary 5 Move the burner on the interior control panel to the ON position 6 Make sure the interlock switch is depressed 7 Verify that 12V DC power is present at Pin B4 of the diesel burner controller If...

Page 97: ...General Troubleshooting Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 97 System Schematics NOTE All connectors are shown from Pin insertion side CONTROLLER PIN OUT REFERENCE...

Page 98: ...General Troubleshooting Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 98 System Schematics ZONE THERMOSTATS ZONE HEAT EXCHANGERS...

Page 99: ...General Troubleshooting Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 99 System Schematics DIESEL BURNER...

Page 100: ...General Troubleshooting Aqua Hot 250 D03 Diesel Series Service Manual REV 220302 p 100 System Schematics ELECTRIC ELEMENT SENSORS AND THERMOSTATS...

Page 101: ...nce 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...

Page 102: ...een 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...

Page 103: ...within the heating solution the water s heat absorption properties are compromised Ultimately this could inhibit the Aqua Hot from providing adequate domestic hot water and interior heating Additiona...

Page 104: ...from such defects which would occur in the manufacturing of the product Thus problems due to improper specifications improper installations improper use the use of accessory parts or parts not authori...

Page 105: ...ng Systems LLC 7501 Miller Drive Frederick CO 80504 Visit us online at www aquahot com Call us at 574 AIR XCEL 574 247 9235 2022 Aqua Hot Heating Systems LLC Printed in the USA Service Manual 200SERIE...

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