Aqua-Hot 375D User manual

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

Table of Contents
© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
General Information
Danger, Warning, Caution, and Note Box Definitions...................................................Page 6
Section 1: Introduction To The Aqua-Hot 375D
Technical Information ...................................................................................................Page 7
I.D. Label Sample ........................................................................................................Page 8
Aqua-Hot Heater Overview...........................................................................................Page 9-11
Aqua-Hot Operational Flow-Chart ................................................................................Page 12
Antifreeze and Water Heating Solution……………………………………………………..Page 13-14
Section 2: Interior Switch Panel
Diesel-Burner Switch....................................................................................................Page 15
Electric Element Switch................................................................................................Page 15
Switch Panel Wiring Schematic....................................................................................Page 16
Section 3: Exhaust System
Exhaust System Requirements ....................................................................................Page 19
Section 4: Aqua-Hot Components
Interlock Switch ............................................................................................................Page 20
Float Switch..................................................................................................................Page 21
Diesel Burner Control Thermostat ................................................................................Page 22-23
Electric Element Control Thermostat ............................................................................Page 24-25
Electric Element High Limit Thermostat .......................................................................Page 26
Diesel Burner High Limit Thermostat (Left) ..................................................................Page 27
Diesel Burner High Limit Thermostat (Right) ................................................................Page 28
Low Temperature Cutoff Thermostat............................................................................Page 29-30
Interior Heating Zone Check Valve...............................................................................Page 30-31
Domestic Water Tempering Valve................................................................................Page 32-33
Interior Heating Zone Circulation Pumps 1 & 2 ............................................................Page 33-34
Stir Pump (Circulation Pump #2) ..................................................................................Page 35
Electric Heating Element ..............................................................................................Page 36-37
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

Table of Contents
© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
Section 6: Diesel-Burner
General Recommended Maintenance..........................................................................Page 46
General Component Overview .....................................................................................Page 47
Diesel-Burner Operational Overview ............................................................................Page 48-49
I.D. Label Sample.........................................................................................................Page 50
Controller Plug..............................................................................................................Page 51-52
Wiring Schematic .........................................................................................................Page 43
Controller Wiring Schematic…………………………………………………………………Page 54
Section 7: Detaching and Reattaching the Diesel-Burner
Detaching the Diesel-Burner ........................................................................................Page 55-58
Reattaching the Diesel-Burner...…………………………………………………………….Page 59-62
Section 8: Diesel-Burner Components and Repair Information
Diesel-Burner Component Overview ............................................................................Page 63
Mounting Gasket ..........................................................................................................Page 64
Air-Tube Assembly .......................................................................................................Page 64-65
Fuel Nozzle ..................................................................................................................Page 65-67
Igniter Assembly...........................................................................................................Page 67-68
Ignition Electrode Adjustment and Cleaning.................................................................Page 69-70
Ignition Module Assembly ............................................................................................Page 70-72
Igniter Gasket Kit..........................................................................................................Page 71-72
Flame Sensor and Flame Sensor Socket .....................................................................Page 73-74
Fuel-Supply Tube Assembly.........................................................................................Page 75
Fuel Pump Assembly ...................................................................................................Page 75-77
Cord-Set.......................................................................................................................Page 78-79
Air Shutter ....................................................................................................................Page 79-80
Air Band .......................................................................................................................Page 81-82
Escutcheon Plate Spline Nut........................................................................................Page 83
Escutcheon Plate .........................................................................................................Page 84-85
Air Guide ......................................................................................................................Page 85-86
Coupling .......................................................................................................................Page 87
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

Table of Contents
© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
Section 10: Troubleshooting
The Diesel-Burner switch has been turned on; however, the diesel-burner fails
to operate .....................................................................................................................Page 97
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...............................Page 98
The Diesel-Burner switch has been turned on; however, multiple attempts are
required before the diesel-burner will ignite..................................................................Page 98
The Aqua-Hot’s exhaust system sputters while the diesel-burner is operating.............Page 98
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; however, the interior and/or fresh
water tank heat exchanger fans are not operating .......................................................Page 99
The Aqua-Hot is operating, but the domestic hot water system is not producing
hot water ......................................................................................................................Page 99
The Electric Element switch has been turned on; however, the Aqua-Hot’s
120 Volt-AC electric heating element does not operate ............................................. Page 100
Appendix A: Wiring Diagram .....................................................................................Page 101-103
Appendix B: Wire Gauge Chart.........................................................................................Page 104
Appendix C: Winterization Process..................................................................................Page 105
Appendix D: Extreme Cold Weather Operation ......................................................Page 106 - 107
Appendix A: Annual Maintenence .............................................................................Page 108-117

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© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
GENERAL INFORMATION:
This manual is designed to aid trained and qualified service
technicians with the process of troubleshooting and servicing
the Aqua-Hot 375D Hydronic Heating System.
The Aqua-Hot features a 12 Volt-DC powered Diesel-Burner
and a 120 Volt-AC, 1500-Watt Electric Heating Element.
These two heating sources are used in conjunction with an
FDA approved “GRAS” (Generally Recognized as Safe)
propylene glycol based boiler antifreeze and water heating
solution in order to provide a continuous supply of domestic
hot water, interior/fresh water tank heating, independent inte-
rior zone heating.
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
order to avoid potential hazards which could result in injury,
death, product damage, and/or property damage.
Should additional assistance be needed, please contact the
Technical Support Department at 1-800-685-4298, Monday
through Friday between the hours of 7:00 AM and 4:00 PM
Mountain Standard Time.
Danger, Warning, Caution, and Note Box Definitions
Danger, Warning, Caution, and Note boxes appear through-
out this manual as a means of alerting the service technician
to important information.
Indicates that personal injury is likely or imminent
Indicates that serious damage to the heater will occur
and personal injury is possible as well.
Indicates that damage to the heater is possible.
NOTE: Indicates information that requires special
attention by the service technician.

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© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
SECTION 1: INTRODUCTION TO THE AQUA-HOT 375D
Diesel Burner, Fuel Consumption (Continuous Operation).......................................................................................................... 0.40 gal/hr
Heater, Voltage/Maximum Power Consumption...................................................................................................... 12 Volt-DC/245 watts
Electric Heating Element specifications ....................................................................................................................120 Volt-AC/1500 watts
Zone Heat Circulation Pump specifications ....................................................................................................(2) 12 Volt-DC/21 watts each
Number of Heating Zones............................................................................................................. Maximum of 2, plus Bay Heat Exchanger
Domestic Water Heating Capacity............................................................................................................................Continuous/On-Demand
Dimensions................................................................................................................................................................... 16.75”H x 18”W x 29.5”L
Dry Weight ..........................................................................................................................................................................approximately 155 lbs.
Wet Weight..........................................................................................................................................................................approximately 200 lbs.
NOTE: All vehicle installations must comply with the requirements listed in the Recreational Vehicle Industry Associ-
ation’s (RVIA) ANSI/NFPA 1192 Handbook for Recreational Vehicle Standards. To receive a copy of this handbook
and other pertinent RVIA Standards, write to: Recreation Vehicle Industry Association, 1896 Preston White Drive,
P.O. Box 2999, Reston, VA 22090-0999, call them at [phone], or visit them online at www.rvia.org.
Figure 1

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© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
SECTION 1: INTRODUCTION TO THE AQUA-HOT 375D
For installation only in a compartment that is completely closed off from living quarters and accessible only
from the outdoors.
The Exhaust System MUST NOT terminate beneath the vehicle or under an openable window or vent.
Combustion Air MUST BE supplied from outside the vehicle.
CAUTION: THIS APPLIANCE OPERATE ON BOTH AC AND DC POWER,
USE COPPER CONDUCTORS ONLY!
Use a 25-Amp fuse for over-current protection for the DC power supply.
Use a circuit breaker that cuts power at 20-Amps maximum for over-current protection for the 120-VAC power
supply.
Mount the Heater near a bay/storage door so that the Access Cover can be easily removed for service.
WARNING: DO NOT OPERATE APPLIANCE WITH ACCESS COVERS REMOVED.
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
Minimum Heater Clearances:
Front - Open Access
Back - 0 inches
Top - 6 inches

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© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
SECTION 1: INTRODUCTION TO THE AQUA-HOT 375D
Figure 2

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© 2009 Aqua-Hot® 375D Hydronic Heating System Service Manual—Rev. A
SECTION 1: INTRODUCTION TO THE AQUA-HOT 375D
120 Volt-AC
Relay
Zone 1 Relay
Zone 2 Relay
Fuse Block
Ground Strip
Figure 3