Aqua-Hot 375-d Service Manual
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Aqua-Hot 375-d Service Manual

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SERVICE MANUAL
AHE-375-D02
© 2009 Aqua-Hot Heating Systems Inc.

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Summary of Contents for Aqua-Hot 375-d

  • Page 1 SERVICE MANUAL AHE-375-D02 © 2009 Aqua-Hot Heating Systems Inc.

  • Page 3: Table Of Contents

    Electric Heating Element A.C. Relay ................Page 38-39 Interior Heating Zone Relay - Fans ................Page 40 Interior Heating Zone Relay - Pumps ................Page 40 Section 5: Filling/Draining The Aqua-Hot 375D With Heating Solution Filling the Aqua-Hot.…………………………………………………………………………..Page 42-44 Draining The Aqua-Hot………………………………………………………………………..Page 45 ®...
  • Page 4 Blower Wheel ....................... Page 88 Blower Motor ........................ Page 89-92 Diesel-Burner Controller ....................Page 93 Section 9: Switch Panel Blinking Fault Indicator Light Diesel-Burner Fault Codes ................... Page 94-96 ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 5 The Aqua-Hot’s exhaust system produces white smoke after ignition ......Page 98 The Aqua-Hot’s exhaust system produced black smoke after ignition ......Page 98 The Aqua-Hot is operating, but an interior and/or fresh water tank heating zone is not working….…………………………………………………………..……………………..Page 99 The Aqua-Hot is at operating temperature;...

  • Page 6: General Information

    Please note that all Danger, Warning, Caution, and Note box- es, appearing as needed throughout this manual, must be reviewed and adhered to during servicing of the Aqua-Hot in Indicates that damage to the heater is possible. order to avoid potential hazards which could result in injury, death, product damage, and/or property damage.

  • Page 7: Section 1: Introduction To The Aqua-Hot 375D

    RVIA Standards, write to: Recreation Vehicle Industry Association, 1896 Preston White Drive, P.O. Box 2999, Reston, VA 22090-0999, call them at (703) 620-6003, or visit them online at www.rvia.org. — Page 7 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 8: Label Sample

    Minimum Heater Clearances: Front—Open Access Back— 0 inches Top — 6 inches Sides—0 inches Install in strict compliance with local codes, NFPA 1192, and the manufacturer’s instructions — Page 8 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 9: Aqua-Hot Heater Overview

    1: I 375D ECTION NTRODUCTION TO THE Figure 2 — Page 9 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 10 1: I 375D ECTION NTRODUCTION TO THE 120 Volt-AC Relay Figure 3 Zone 1 Relay Zone 2 Relay Fuse Block Ground Strip — Page 10 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 11 10 L LOCK EMPERATURE HERMOSTAT 11 F IRCULATION LOAT WITCH 12 D IESEL URNER IESEL URNER IMIT HERMOSTATS Electric Element High-Limit Thermostat Electric Element Control Thermostat — Page 11 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 12: Aqua-Hot Operational Flow-Chart

    NTRODUCTION TO THE AQUA NOTE: The heat exchang- ers fans will not operate until the Boiler tank reach- es a minimum of 150* F Chart 1 — Page 12 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 13: Antifreeze And Water Heating Solution

    Aqua-Hot Heating of chemical inhibitors. Due to their potentially hazardous Systems Inc. recommends CAMCO’s Boiler Antifreeze properties, they should never be used in the Aqua-Hot’s -100° F. Hydronic Heating System. Antifreeze Types:...
  • Page 14 Boiling Point: The Aqua-Hot utilizes the antifreeze and water heating solu- tion as a transportation means for the heat produced from the internal processes. The antifreeze absorbs the heat created until its boiling point is reached;...

  • Page 15: Section 2: Interior Switch Panel

    Burner; reference Figure 5. This procedure allows the Diesel Volt-AC Electric Heating Element; reference Figure 5. This -Burner to operate and supply heat to the Aqua-Hot’s Boiler procedure allows the 120 Volt-AC Electric Heating Element Tank, which will heat the Aqua-Hot’s antifreeze and water to operate and supply heat to the Aqua-Hot’s Boiler Tank,...

  • Page 16: Switch Panel Wiring Schematic

    2: I ECTION NTERIOR WITCH ANEL Figure 6 — Page 16 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 17 2: I 2011 ECTION NTERIOR WITCH ANEL FOR UNITS MANUFACTURED AFTER ANUARY Figure 6a — Page 17 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 18 This Page Intentionally Left Blank — Page 18 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 19: Section 3: Exhaust System Exhaust System Requirements

    XHAUST YSTEM EQUIREMENTS  Because the Aqua-Hot’s exhaust is hot and must be kept The exhaust must be able to freely exit away from the away from any heat-sensitive material, the exhaust system vehicle without any obstructions. should be checked to ensure that it continues to meet the following requirements: ...

  • Page 20: Section 4: Aqua-Hot Components

    1. Disconnect the interlock switch’s wires by pulling the quick connectors from the switch’s spade terminals. Sensors/Switches 2. Release the interlock switch from the Aqua-Hot cabinet by pushing in on the locking tabs and pulling the inter- Interlock Switch: lock switch.

  • Page 21: Float Switch

    Aqua-Hot’s boiler tank using the drain valve, Approxi- mately 2 gallons will need to be drained.. 1. Verify that the Aqua-Hot’s boiler tank is full of the anti- freeze and water heating solution. 3. Disconnect the float switch’s wires by separating the quick-disconnect terminals.

  • Page 22: Diesel Burner Control Thermostat

    The Aqua-Hot is consid- If continuity exists, complete the following: ered to be at operating temperature between 158°F and 190°...
  • Page 23 ALLOW THE HEATER TO COOL BEFORE SERVICING COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY 6. Screw the replacement control thermostat into the port on the Aqua-Hot boiler tank and tighten securely with a 1. Ensure that the Aqua-Hot has been completely shut down 7/8 socket.

  • Page 24: Electric Element Control Thermostat

    The Aqua-Hot is consid- AILURE TO DISCONNECT ALL POWER SUPPLIES AND OR TO ered to be at operating temperature between 158°F and 190°...
  • Page 25 Control Thermostat: Electric Element (continued) Replacement Procedure: 5. Install the replacement control thermostat, tightening 1. Ensure that the Aqua-Hot has been completely only to 15 in/lbs. Do not overtighten. shut down and that all power sources have been disconnected. 6. Connect the replacement control thermostat’s wires in the same configuration as the removed thermostat’s...

  • Page 26: Electric Element High Limit Thermostat

    The high-limit thermostat allows the current for the heating element to pass through it until the boiler tank reaches a tem- 1. Ensure that the Aqua-Hot has been completely shut perature of 215°F. Should this temperature be reached, the down and that all power supplies have been disconnect-...

  • Page 27: Diesel Burner High Limit Thermostat (Left)

    2. Remove the two wires from the defective high-limit NOTE: Bypassing the high-limit thermostats is for testing thermostat by pulling firmly on the wires. only and must not be used for the Aqua-Hot normal operation. 3. Using a 5/8 wrench or socket, remove the defective high -limit thermostat from the Aqua-Hot’s boiler tank.

  • Page 28: Diesel Burner High Limit Thermostat (Right)

    2. Remove the two wires from the defective high-limit thermostat by pulling firmly on the wires. NOTE: Bypassing the high-limit thermostats is for testing only and must not be used for the Aqua-Hot’s nor- 3. Using a 5/8 wrench or socket, remove the defective high mal functioning.

  • Page 29: Low Temperature Cutoff Thermostat

    Troubleshoot the low-temperature cutoff thermostat if the is necessary for the thermostat to trip. following conditions have occurred: B. Inspect the wiring to ensure that the Aqua-Hot is  There is a lack of interior heat. wired properly and that the low-temperature cutoff thermostat has not been bypassed via jumper wires.

  • Page 30: Interior Heating Zone Check Valve

     There is a lack of interior heat in a particular zone. 3. Check the Aqua-Hot’s antifreeze and water heating solu- tion’s ratio of water to propylene glycol. The mixture Troubleshooting: ratio should be approximately 50/50. If the solution is comprised fully of antifreeze (100%), the check valves 1.
  • Page 31 CAUSE SERIOUS DAMAGE OR PERSONAL INJURY on the replacement check valve, ensuring that they are 1. Ensure that the Aqua-Hot has been completely shut down installed properly with the 90* hose barb on the arrow and that all power sources have been disconnected. Also, side of the check valve.

  • Page 32: Domestic Water Tempering Valve

    4. Disconnect the pex pipe and fittings from the tempering valve assembly. The tempering valve for the Aqua-Hot mixes the heated do- mestic water from the boiler tank with cold domestic water at 5. Remove the pressure relief valve assembly from the a preset ratio to reduce the risk of scalding.

  • Page 33: Interior Heating Zone Circulation Pumps 1

    The Zone pumps first draw the heated antifreeze and water Block for the zone pumps, #56(WHT). heating solution from the Aqua-Hot’s boiler tank, then pro- a. If No voltage, replace the fuse. pel it through the hydronic heating system’s interior heat b.
  • Page 34 9. Refill the Aqua-Hot’s boiler tank with the antifreeze and 2. Drain the antifreeze and water heating solution from the water heating solution. Reference Section 5 for filling i- Aqua-Hot’s boiler tank using the drain valve.

  • Page 35: Stir Pump (Circulation Pump #2)

    The stir pump circulates the antifreeze and water heating solution within the Aqua-Hot’s boiler tank in order to ensure B. Using a Volt Meter check the zone 2 relay for even-heating of the solution. To accomplish this, the stir voltage on the #4 pin.

  • Page 36: Electric Heating Element

    Troubleshoot the electric heating element if the following condition has occurred: If the boiler tank is above 185°F, the Aqua-Hot is at operating temperature and requires no heat.  There is a lack of hot domestic water and interior heat when the electric element is selected as the heating 4.
  • Page 37 8. Connect the wires removed from the defective electric COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY heating element to the replacement electric heating ele- 1. Ensure that the Aqua-Hot has been completely shut ment utilizing crimp terminals. down and that all power sources have been disconnect- ed.

  • Page 38: Electric Heating Element A.c. Relay

    If no power is present follow troubleshooting section to replace the AC relay. guide for the electric element switch. B. If 12 Volts of DC power are present, continue: — Page 38 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 39 TO ALLOW THE HEATER TO COOL BEFORE SERVICING COULD CAUSE SERIUOS DAMAGE OR PERSONAL INJURY 1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnect- 2. Also, ensure that the motorhome is not connected to shore power and that a generator is not running during this replacement procedure.

  • Page 40: Interior Heating Zone Relay - Fans

    2. Since the Aqua-Hot 375D is a hot water priority system, 5. On the zone relay, check pin #8 for 12 VDC +. make sure the Low Temperature cut-off Thermostat is...
  • Page 41 NOTE: Even though the Aqua-Hot 375 is a Hot Water Pri- 6. On the zone relay, check pin #4 for 12 VDC +. ority system, and utilizes a Low Temperature Cut-Off ther-...

  • Page 42: Filling The Aqua-Hot

    Reference Figure please contact the Aqua-Hot Heating Systems Product Appli- cation Department at 1-800-685-4298. 1. Open the Aqua-Hot’s drain valve located at the front of Figure 24 the heater. Reference Figure 25. 2. Connect a piece of 1/2 inch PEX-type tubing to the drain valve.

  • Page 43: Wiring Schematic

    Be sure the valve is closed when finished by hand-tightening. Look for the solution to enter the over- 9. Check the Aqua-Hot’s expansion tank and top it off to flow tube attached to the expansion tank connection on the cold level mark with the 50/50 antifreeze and water top of the Aqua-Hot.
  • Page 44 Terminal Block for Switches, Heat Exchanger Fans and Thermostats Figure 27 Zone 1 Thermostat Connection Terminal Zone 2 Thermostat Connection Terminal — Page 44 — — Page 44 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 45: Draining The Aqua-Hot

    Aqua-hot to a bucket. 2. Open the Aqua-Hot’s drain valve located at the front of Ensure that the overflow tube is connected from the Aqua- the heater. Reference Figure 27.

  • Page 46: Section 6: Diesel-Burner

    To keep the Aqua-Hot running smoothly, it is ideal to have the Diesel-Burner tuned-up annually. A tune-up should consist of a new Fuel Nozzle and Fuel Filter, along with a thorough cleaning of the Combustion Chamber, if necessary (reference Figure 29).

  • Page 47: General Component Overview

    6: D ECTION IESEL URNER Figure 31 Figure 31A Figure 31B Figure 31C — Page 47 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 48: Diesel-Burner Operational Overview

    6: D ECTION IESEL URNER Chart 2 — Page 48 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 49 6: D ECTION IESEL URNER Chart 2 (Continued) — Page 49 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 50: Label Sample

    6: D ECTION IESEL URNER — Page 50 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 51: Controller Plug

    6: D ECTION IESEL URNER Figure 32 Figure 33 — Page 51 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 52 (Orange) Motor SIG (Black) Motor - (Red) Ignition Coil + (Black) Ignition Coil - (Violet) Fuel Solenoid + (White) Fuel Solenoid - (Pink) Motor + — Page 52 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 53 6: D ECTION IESEL URNER Figure 35 — Page 53 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 54: Controller Wiring Schematic

    6: D ECTION IESEL URNER Figure 36 — Page 54 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 55: Section 7: Detaching And Reattaching The Diesel-Burner

    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 replacement procedure. Step 1: Turn Off the Diesel Switch Figure 37 1.
  • Page 56 1. Locate the Diesel-Burner’s white, electrical plug 2. Press back on the two tabs securing the connection to the Diesel-Burner Controller. connections together Figure 40 Figure 40A — Page 56 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 57 2. Using an 11/16 wrench, loosen the nuts securing burner and the corresponding fuel lines. each fuel line to the fuel pump assembly. Figure 42 Figure 42A — Page 57 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 58 EATTACHING THE IESEL URNER Step 5: Remove the Diesel Burner from the Aqua-Hot 1. The Diesel-Burner is secured to the Aqua-Hot with 2. Carefully lift the Diesel-Burner away from the Aq- three nuts that can be removed by using a 9/16 ua-Hot.
  • Page 59 2. Finger tighten all three nuts previously removed to the combustion chamber and slide onto the bolts secure the Diesel-Burner to the boiler tank. protruding from the boiler tank. Figure 48 Figure 49 — Page 59 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 60 2. Using an 11/16 wrench, tighten the nuts on the Diesel-Burner’s Fuel Pump Assembly. fuel lines to the Fuel Pump Assembly to secure the lines in place. Figure 51 Figure 52 — Page 60 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 61 Step 4: Reconnect the Diesel Burner to the Diesel Burner Controller 1. Push the Diesel-Burner and Diesel-Burner Con- 2. Press down on the tabs to secure them together. troller’s connections together. Figure 53 Figure 54 — Page 61 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 62 1. Set the access cover back into place on the Aqua-Hot. Figure 55 2. Insert the bolts in the two locations on the Aqua-Hot to se- cure the cover in place; tighten the bolts securely. NOTE: The access cover must be installed prior to operation as...

  • Page 63: Section 8: Diesel-Burner Components And Repair Information

    19 ..Blower Wheel 8 ..Flame Sensor Socket 20 ..Blower Motor 9 ..Fuel-Supply Tube 21……..Diesel-Burner Controller 10 ..Fuel Pump Assembly 11……..Cord-Set — Page 63 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 64: Mounting Gasket

    Air-Tube Assembly: Replacement Indicator: The Mounting Gasket should be replaced each time the Diesel- The Aqua-Hot operates o both AC and DC power. Be sure Burner is detached from the Aqua-Hot. to disconnect the 120 Volt-AC power supply from the Aqua -Hot prior to servicing.

  • Page 65: Fuel Nozzle

    Replacement Procedure: The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply from the Aqua-Hot NOTE: The Diesel-Burner does not need to be detached prior to servicing.
  • Page 66 NOTE: The Diesel-Burner will fire anytime the Diesel-Burner bly. switch is turned on, even if it is turned back off before the Diesel-Burner actually fires. Figure 59 — Page 66 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 67: Igniter Assembly

    4. Reach into the Blower Housing and pull the Igniter As- sembly out of the Diesel-Burner. The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply prior to NOTE: To ease the removal of the Igniter Assembly, rotate servicing.

  • Page 68: Ignition Electrode Adjustment And Cleaning

    3/8 inch socket wrench. Ignition Electrodes are properly adjusted with the Beckett T-Gauge; adjust if needed. 2. Referencing Figures 63 and 64, properly align the Ignition Electrodes. — Page 68 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 69 8: D ECTION IESEL URNER OMPONENTS AND EPAIR NFORMATION Figure 62 Figure 63 Figure 64 Figure 63A Figure 64A — Page 69 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 70: Ignition Module Assembly

    #5 and the #6 Terminals on the Diesel Burner’s white, electrical plug; reference figure The Aqua-Hot operates on both AC and DC power. Be sure 3. Work the wires out and away from the Diesel-Burner; ref- to disconnect the 120 Volt-AC power supply prior to servic- erence Figure ?.

  • Page 71: Igniter Gasket Kit

    4. Close the Ignition Module Assembly and secure with the Ignition Module Retaining Clips. Flame Sensor Gasket Replacement Procedure: The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply prior to 1. Loosen the two screws securing the Ignition Module Re- servicing.
  • Page 72 8: D ECTION IESEL URNER OMPONENTS AND EPAIR NFORMATION Figure 67 Figure 68 — Page 72 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 73: Flame Sensor And Flame Sensor Socket

    Gasket, pull the defective Flame Sensor straight out from the Flame Sensor Socket. The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply prior to servic- 3. Insert the replacement Flame Sensor’s pins into the Flame ing.
  • Page 74 9. Close the Ignition Module Assembly and secure with the set the Flame Sensor Socket and Mounting Bracket flat against Ignition Module Retaining Clips. the Ignition Module Assembly. Figure 69 Figure 29 — Page 74 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 75: Fuel-Supply Tube Assembly

    NOTE: The Diesel-Burner does not need to be detached from the Aqua-Hot for this replacement procedure. The Aqua-Hot operates on both AC and DC power. Be 1. Loosen both hexagonal locknuts on either end of the Fuel- sure to disconnect the 120 Volt-AC power supply prior to Supply Tube Assembly with a 7/16 inch open-end wrench.
  • Page 76 Aqua-Hot; then, remove these lines completely. Diesel-Burner. 2. Attach short pieces of fuel line to both the Aqua-Hot’s Fuel Return and Fuel Supply ports; reference Figure 31. 4. Using a 3/8 inch socket wrench, remove the two bolts se- curing the Fuel Pump Assembly to the Blower Housing.
  • Page 77 Plate Fuel Connection and Fuel Pump Assembly and the Diesel-Burner” located in Section 7 of this manual, tighten both hexagonal locknuts with a 7/16 inch open-end reattach the Diesel-Burner to the Aqua-Hot. wrench. Be sure to remove the clamps from the Fuel Supply and Fuel Return lines prior to starting the Diesel-Burner.

  • Page 78: Cord-Set

    #8 terminals on the Diesel-Burner’s white, electrical plug. The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply prior to 3. Work the wires and Cord-Set out and away from the Die- servicing.

  • Page 79: Air Shutter

    Fuel-Supply Tube Assembly with a 7/16 inch open- air level, which mixes with the diesel fuel spray and is ignited end wrench. in order to establish a flame to heat the Aqua-Hot’s Boiler Tank. B. Pull the Fuel-Supply Tube Assembly away from the Diesel-Burner.
  • Page 80 Adjustment Scale once installed. NOTE: The Mounting Gasket must be replaced each time the 9. Insert the Fuel Pump Assembly and attached Coupling, if Diesel-Burner is detached from the Aqua-Hot; refer- applicable, into the Blower Housing. ence the procedure for “Detaching and Reattaching the Diesel-Burner,”...

  • Page 81: Air Band

    6. Using a 5/16 inch socket wrench, loosen and remove the bolt securing the Air Shutter to the Blower Housing. The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply prior to 7.
  • Page 82 NFORMATION NOTE: The Mounting Gasket must be replaced each time the Setting the Combustion-Air Level: Diesel-Burner is detached from the Aqua-Hot; refer- ence the procedure for “Detaching and Reattaching For information regarding setting the Diesel-Burner’s Combus- the Diesel-Burner,,” located in Section 4 of this manu- tion-Air level, please contact the Technical Support Depart- al for instructions.

  • Page 83: Escutcheon Plate Spline Nut

    Fuel Pump Assembly, but must be loosened to rotate out of the way. The Aqua-Hot operates on both AC and DC power. Be 2. Using a 7/16 inch open-end wrench, remove the Fuel- sure to disconnect the 120 Volt-AC power supply prior to Supply Tube Assembly’s hexagonal locknut, which se-...

  • Page 84: Escutcheon Plate

    Fuel-Supply Tube to the Igniter Assembly. 3. Remove the Fuel-Supply Tube from the Igniter Assembly The Aqua-Hot operates on both AC and DC power. Be and rotate out of the way. sure to disconnect the 120 Volt-AC power supply prior to servicing.

  • Page 85: Air Guide

    Be sure to clamp off the Fuel Supply and Return lines prior to beginning this replacement procedure. The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply prior to 1. Following the procedure for “Detaching and Reattaching servicing.
  • Page 86 NOTE: The Mounting Gasket must be replaced each time the with the two screws previously removed. Diesel-Burner is detached from the Aqua-Hot; refer- ence the procedure for “Detaching and Reattaching 7. If applicable, return the Air Band to its original configura- the Diesel-Burner,”...

  • Page 87: Coupling

    Housing, under the Air Guide, and slide it onto the Fuel Pump Assembly’s shaft. The Aqua-Hot operates on both AC and DC power. Be NOTE: It may be necessary to rotate the Coupling slowly to sure to disconnect the 120 Volt-AC power supply prior to properly seat it on the Fuel Pump Assembly’s shaft;...

  • Page 88: Blower Wheel

    Blower Motor’s shaft. 4. Place a 0.030 (1/32 ± 1/64) inch Feeler Gauge on top of The Aqua-Hot operates on both AC and DC power. Be the Blower Motor, then slide the replacement Blower sure to disconnect the 120 Volt-AC power supply prior to Wheel onto the Blower Motor’s shaft until it contacts the...

  • Page 89: Blower Motor

    Switch Panel’s Diesel-Burner switch is in the ON position as an electrical shock can occur. The Aqua-Hot operates on both AC and DC power. Be sure to disconnect the 120 Volt-AC power supply prior to NOTE: Once the Diesel-Burner switch is activated, the volt- servicing.
  • Page 90 NOTE: If the Blower Motor’s yellow/orange signal wire does B. Rotate the Blower Wheel until the set screw is cen- not reflect current when the Aqua-Hot’s Control Ther- tered on the flat of the Blower Motor’s shaft. mostat is calling for heat, the Diesel-Burner Controller may need to be replaced.
  • Page 91 8: D ECTION IESEL URNER OMPONENTS AND EPAIR NFORMATION Figure 84 Figure 85 — Page 91 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 92 8: D ECTION IESEL URNER OMPONENTS AND EPAIR NFORMATION Figure 86 Figure 87 — Page 92 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 93: Diesel-Burner Controller

    2. Locate the white, electrical plug connecting the Diesel- Burner Controller to the Aqua-Hot’s wiring harness, then The Aqua-Hot operates on both AC and DC power. Be press back on the two tabs securing the two connections sure to disconnect the 120 Volt-AC power supply prior to together.

  • Page 94: Diesel-Burner Fault Codes

    If the fault codes are not corrected by the checks listed below each specific code, NOTE: contact the Aqua-Hot Heating Systems Technical Support Department at 1-800-685-4298. Fault Code 0 (Indicator light is not illuminated, but the Diesel-Burner Switch is ON.): 1.
  • Page 95 Fault Code 6: 1. Did the left High-Limit Thermostat (connected to wires #15 and #16) trip? 2. Is The insulation, surrounding the Aqua-Hot Boiler Tank, shorting out the thermostat to ground? Fault Code 7: 1. Check the Fuel Solenoid for an external short.
  • Page 96 9: S ECTION WITCH ANEL LINKING AULT NDICATOR IGHT — Page 96 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 97: Section 10: Troubleshooting

    Is the Indicator Light flashing a fault code? If so, refer to the “Switch Panel Blinking Fault Indicator Light” section. b. Check the Control Thermostat (The Aqua-Hot’s normal operating range is 160-190°F) for functionality by locating the control thermostat on the heater, disconnecting the wires and placing a jumper wire on the harness between wires #10 &...

  • Page 98: The Diesel-Burner Switch Has Been Turned On And The Diesel-Burner's Blower Motor Has Begun To Operate; However, The Diesel-Burner Does Not Ignite

    E. Verify that the Combustion-Air is set to the proper level. F. Check that the Diesel-Burner’s gaskets are properly seated and not creating an obstruction. G. Check that the Diesel-Burner is firmly attached to the Aqua-Hot. H. Ensure that the Diesel-Burner’s gaskets are not worn or damaged.

  • Page 99: The Aqua-Hot Is Operating, But An Interior And/Or Fresh Water Tank Heating Zone Is Not Working

    The Aqua-Hot is operating, but the domestic hot water system is not producing hot water. 1. Reference Section 1, pages 13-14, and ensure that the Aqua-Hot is using the appropriate antifreeze type and mixture ratio. 2. Verify that the water outlet’s domestic hot water flow rate is at or below 1.5 Gallons per Minute (GPM).

  • Page 100: The Electric Element Switch Has Been Turned On; However, The Aqua-Hot's 120 Volt-Ac Electric Heating Element Does Not Operate

    1. Ensure that the motorhome is plugged into shore power or has the generator running. 2. Ensure the Aqua-hot is not up to maximum operating temperature, by checking it with a digital thermometer. 3. With the Interior Switch Panel’s Electric Element switch on, locate the Electric Element’s 120VAC relay and check for DC volt- age at Pin #0 (+) and Pin #1 (-);...

  • Page 101: Appendix A: Wiring Diagram

    A: W 2011 PPENDIX IRING IAGRAM EATER ANUFACTURED EFORE ANUARY — Page 101 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 102 A: W 2011 PPENDIX IRING IAGRAM EATER ANUFACTURED AFTER ANUARY — Page 102 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 103 — Page 103 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 104: Appendix B: Wire Gauge Chart

    B: W PPENDIX AUGE HART — Page 104 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 105: Appendix C: Winterization Process

    Not winterizing the Aqua-Hot when freezing temperatures this procedure for both the hot and cold faucets. are present will result in serious damage to the Aqua-Hot’s Domestic Water Heating System. Also, be sure to use an 6. Turn off Demand Water pump and remove the hose and re- FDA approved, “GRAS”...

  • Page 106: Appendix D: Extreme Cold Weather Operation

    1/4 tank. B. When was the last time an Annual Service was performed? NOTE: The Aqua-Hot can continue to be used for interior zone heating once the domestic water heating system C. Is the Diesel Fuel liquid or Jelled? has been drained and winterized.
  • Page 107 If there is a lack of Interior Heat During Cold Weather Operation: Note: The 120 Volt-AC Electric Heating Element is the Aqua-Hot’s secondary heat source for heating both the interior and/or the domestic hot water during low heat- ing demand situations (such as when moderate ambient temperatures exist and/or when there is a low demand for domestic hot water).
  • Page 108 General Recommended Maintenance Figure 93 Annually To keep the Aqua-Hot running smoothly, it is ideal to have the Diesel-Burner tuned-up annually. A tune-up should consist of a new Fuel Nozzle and Fuel Filter, along with a thorough cleaning of the Combustion Chamber, if necessary (reference Figure ?).
  • Page 109 NOTE: It is recommended that the replacement fuel filter be filled with clean diesel fuel, prior to installation 4. Remove hose pinch off pliers. Diesel Burner Figure 94 Controller Plug — Page 109 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

  • Page 110: Appendix A: Annual Maintenence

    A. Unplug Diesel-Burner controller Figure 95c Figure 95d C. Remove nuts, securing the Diesel-Burner, and D. Remove Gasket, and inspect for signs of damage. remove. — Page 110 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 111 C. Remove the Flame Tube. D. Clean and inspect the Flame Tube. E. Clean and inspect the Heat Transfer Tabs welded inside the Aqua-hot, using a long handled wire brush. F. Clean and inspect the Flame Tube Spacer. Figure 96...
  • Page 112 NOTE: The Two Flame Tube Mounting Gaskets should be replaced each time the Flame Tube is de- tached from the Aqua-Hot. A. Install the 1st Flame Tube Mounting Gasket on to the boiler tank. B. Install the Flame Tube into the Boiler Tank.
  • Page 113 NOTE: After connecting Fuel lines, going to Diesel-Burner, it is recommended to remove pinch off pliers previously used on the fuel lines coming into the heater. — Page 113 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 114 ROCEDURE Step 5: Replace the Fuel Nozzle NOTE: The Diesel-Burner does not need to be detached from the Aqua-Hot in order to replace the fuel nozzle. NOTE: Before Removing Igniter Assembly, it is recommended to unplug the control unit, to pre- 1.
  • Page 115 B. Adjust the Height of the Electrodes using the replace the fuel nozzle. Beckett T-Gauge NOTE: Be sure to tighten nozzle completely, to prevent fuel leakage. — Page 115 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 116 Then Securely tighten Fuel High Pressure Pipe. D. Using a flat head screw driver, Securely Tighten C. Close Ignition Coil. the retaining clips securing the ignition coil in place. — Page 116 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 117 D. Run Interior Heating zones Monthly. E. If they are going to winterize their motor home, make sure they use the winterization antifreeze. DO NOT BLOW OUT WITH AIR. — Page 117 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 118 — Page 118 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 119 — Page 119 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...
  • Page 120 SERVICE MANUAL 15549 East Highway 52 | Fort Lupton, CO 80621 Toll free: 800.685.4298 | phone: 303.659.8221 | fax:303.857.7881 www.aquahot.com — Page 120 — ® © 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A...

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