Aqua-Hot 375D User manual

INSTALLATION MANUAL
© 2011 Aqua-Hot Heating Systems Inc.

CAUTION:
The Aqua-Hot tank and heating loop operate at
0.0 psi (zero pressure system). Air pressure
applied to the tank MUST NOT exceed 20 psi.
Excess pressure will result in internal damage.
CAUTION:
Before welding or plasma cutting on any coach;
it is necessary to disconnect the electric wiring to
the Aqua-Hot System.
Failure to disconnect the wires from the
Aqua-Hot System before using a welder or a
plasma cutter on the coach may cause damage to
the Aqua-Hot.

© 2011 Aqua-Hot®375-D Installation Manual
TABLE OF CONTENTS
Aqua-Hot 375-D Installation Manual
Introduction...........................................................................................................................................5
Section 1: Aqua-Hot Hydronic Heating System
Technical Information..........................................................................................................................6
Section 2: Aqua-Hot Installation
Installing the Mounting Tray and the Aqua-Hot..............................................................................10
Overall Aqua-Hot Dimensions...........................................................................................................12
Installing the Cable-Clamp Fittings....................................................................................................14
Installing the Wires into the Terminal Blocks ..................................................................................14
Installing the Expansion Tank............................................................................................................15
Section 3: Hydronic Heating System
Heat Exchanger Location and Clearances.........................................................................................16
Heat Exchanger Mounting Requirements.........................................................................................16
Mounting the Heat Exchangers..........................................................................................................17
Sample Heating System Floorplan......................................................................................................19
Wiring the Heat Exchangers ...............................................................................................................20
Plumbing Requirements.......................................................................................................................22
Plumbing the Hydronic Heating System...........................................................................................23
Section 4: Thermostats
Fresh Water Tank Thermostat............................................................................................................26
Room Thermostats...............................................................................................................................27
Section 5: Domestic Water System
Domestic Water System Requirements .............................................................................................28
Domestic Water System Plumbing.....................................................................................................28
Section 6: Switch Panel
Switch Panel Location..........................................................................................................................30
Switch Panel Mounting........................................................................................................................30
Switch Panel Wiring..............................................................................................................................30
Section 7: Fuel System
Fuel Filter Location ..............................................................................................................................32
Fuel System Requirements...................................................................................................................32
Fuel System Installation

Section 8: Exhaust System
Exhaust System Requirements............................................................................................................35
Installing the Exhaust System .............................................................................................................35
Section 9: Power Source Wiring
Connecting the 12 Volt-DC Power....................................................................................................39
Connecting the 120 Volt-AC Power..................................................................................................39
Installing the Wires into the Terminal Blocks ..................................................................................39
Section 10: Purging the Systems
Purging the Hydronic Heating System...............................................................................................41
Purging the System by Grounding the Zone Thermostat Connection.........................................42
Purging the Domestic Water System..................................................................................................43
Section 11: Initial Start-Up
Activating the Aqua-Hot......................................................................................................................46
Appendices:
Appendix A: Wiring Diagram .............................................................................................................47
Appendix B: Wire Gauge Information..............................................................................................48
Appendix C: Antifreeze Types............................................................................................................49
Appendix D: Antifreeze Mixture Water Quality Recommendations............................................49
Appendix E: Antifreeze Terms and Mixture Ratio..........................................................................50
Appendix F: Measuring Propylene Glycol Using a Refractometer ..............................................52
TABLE OF CONTENTS (CONTINUED)

© 2011 Aqua-Hot®375-D Installation Manual
INTRODUCTION
The Aqua-Hot 375D is a hydronic (water based) heating sys-
tem, and a tank-less hot water system.
The heating system provides moist, quiet, comfortable, inte-
rior heat with up to three separate, thermostatically-
controlled temperature zones, and prevents tank and line
freezing in the bays. The tank-less hot water system
produces 90 gallons per hour of continuous, on-demand hot
water.
This TribridHot™ designated system uses one or a combina-
tion of heat sources to heat FDA-approved Generally Recog-
nized as Safe (GRAS) propylene glycol based antifreeze
solution in the Aqua-Hot’s boiler tank. The 375D features a
120 Volt-AC, 1500 Watt electric element, and a 12 Volt-DC
powered diesel burner.
When AC power is available, plug in. When dry camping,
use the diesel fuel source. The electric power and diesel fuel
sources can be used separately or together.
New Low Emissions Technology virtually eliminates smoke
and smell from the exhaust by reducing total hydrocarbon
emission by 82% making Aqua-Hot the cleanest burning
diesel powered hydronic system available.
This Installation Manual is designed to aid in the installation
process of the Aqua-Hot 375-D Hydronic Heating System by
a trained and experienced technician.
Please note that all Danger, Warning, Caution, and Note
boxes, appearing as needed throughout this manual, must be
reviewed and adhered to during the installation procedure in
order to avoid potential hazards, which could result in injury,
death, product damage, or property damage.
Should additional assistance be needed, please contact
Aqua-Hot Heating Systems 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 Boxes:
Danger, Warning, Caution, and Note boxes appear through-
out this manual as a means of alerting the installer to impor-
tant information.
— Page 5 —
▲DANGER ▲
INDICATES THAT PERSONAL INJURY IS LIKELY OR IMMI-
NENT.
WARNING!
Indicates that serious damage to the heater will occur and
personal injury is possible as well.
CAUTION
Indicates that damage to the heater is possible.
NOTE: Indicates information that requires special attention
by the installer.

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 1: AQUA-HOT HYDRONIC HEATING SYSTEM
Diesel Burner, Heat Input (Firing Rate).................................................................................................................................59,000 BTU/hr
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 Asso-
ciation’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
— Page 6 —

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 1: AQUA-HOT HYDRONIC HEATING SYSTEM
Each Aqua-Hot heating system possesses an I.D. label on the
unit itself. This I.D. label details the specifications of the heater, to what standard it has been tested, and important safety notices.
Figure 2
— Page 7 —
6 Inches
1 Inch
1 Inch
Use a 30-Amp

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 1: AQUA-HOT HYDRONIC HEATING SYSTEM
— Page 8 —
Figure 3
Terminal Block Access
Zone 1 and 2
Outlet Ports
Hot Water
Inlet Port
Hot Water
Outlet Port
Diesel Fuel
Inlet/Outlet
Ports
Zone 1 and 2
Inlet Ports
Air Release
Valve
Expansion Tank
Connection
CAUTION:
The Aqua-Hot tank and heating loop operate at
0.0 psi (zero pressure system). Air pressure ap-
plied to the tank MUST NOT exceed 20 psi. Ex-
cess pressure will result in internal damage.

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 1: AQUA-HOT HYDRONIC HEATING SYSTEM
Figure 4
— Page 9 —
Interlock Switch
Diesel Burner
Controller
Diesel
Burner
Drain Valve
Zone 2
Circulation
Pump
Domestic Water
Assembly
Fuse Block
Zone 2
Relay
Zone 1
Relay

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 2: AQUA-HOT INSTALLATION
Installing the Mounting Tray and the Aqua-Hot:
The Aqua-Hot must be installed in a compartment that is
completely closed-off from living quarters and accessible
only from the outdoors.
Figure 5
— Page 10 —
1 in
3 in
NOTE: Be sure to complete the following when installing
the Aqua-Hot:
Inspect the area beneath the mounting location to
insure that no structural members will interfere with
the cut-out for the mounting tray.
Verify that an adequate support system has been
provided for the Aqua-Hot.
Secure the mounting tray into place prior to
installing the Aqua-Hot.
Remove the access cover fastener from the
Aqua-Hot prior to installation of the Aqua-Hot
into the mounting tray.
Mount the Aqua-Hot securely into the mounting
tray to ensure that the unit does not move or shift
under normal operating conditions.
NOTE: Remove the bolt securing the front of the access cover
to the mounting tray; this bolt will need to be re-
installed once the total installation procedure is com-
plete. Remove the access cover.
1. Reference the following illustrations for mounting informa-
tion:
•
Overall Aqua-Hot dimensions - Figure 8
• Mounting tray information - Figure 7
• I.D. Label noting the “Open Access”
clearance requirement for the front of the heater
- Figure 2
• Service access clearances - Figure 5
2. Cut out the required mounting tray opening. Reference Fig-
ure 7.
3. Install the mounting tray flange into the cut-out opening.
Reference Figure 6.
4. Insert a #10 machine screw into each of the embossed holes
in the mounting tray (total of six required) and tighten to
secure the mounting tray to the motorhome.

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 2: AQUA-HOT INSTALLATION
Figure 6
Figure 7
— Page 11 —
Mounting Tray Flange
(Installed in cut-out)
Underside of Mounting Tray

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 2: AQUA-HOT INSTALLATION
Figure 8
— Page 12 —

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 2: AQUA-HOT INSTALLATION
Figure 9
— Page 13 —

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 2: AQUA-HOT INSTALLATION
Installing the Cable-Clamp Fittings:
Cable-clamp fittings can be installed on either side of the
terminal access area
1. Determine the port side best suited for the current appli-
cation. Reference Figures 10 and 11.
2. Remove the terminal block access cover and set aside in
a location where it will not become damaged or
scratched.
3. For each cable-clamp fitting, remove the nut from the
fitting, insert the fitting into the port with the wire-entry
side facing away from the terminal block access area,
screw the nut onto the fitting, and hand-tighten. Refer-
ence Figures 10 and 11.
Figure 10
— Page 14 —
Figure 11
NOTE: A ferrule is required if stranded wire is being used to
connect to the terminal block
Installing the Wires into the Terminal Blocks
1. Loosen the cable clamps on the installed cable-clamp
fittings. Reference Figure 11.
2. Insert the wires into the terminal block access area
through the appropriate port’s cable clamp fitting and
into the proper terminal.
3. Secure the wires into their terminals by tightening the
corresponding screw on the terminal block. Tighten
terminal screws to 5 inch pounds using a slotted blade
no wider than 1/8”.
4. Hand tighten the cable clamps on each of the cable-
clamp fittings.
5. Re-install the terminal block access cover and tighten
the screws securing the cover to the Aqua-Hot.
NOTE: It is recommended that the wire numbers in
Appendix A be used when installing the Aqua-
Hot in order to assist with differentiating be-
tween the separate heating zones and to aid ser-
vice personnel with troubleshooting.

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 2: AQUA-HOT INSTALLATION
Installing the Expansion Tank:
Select a mounting location that allows for easy access and
clear visibility whenever the particular storage bay door is
open.
1. Mount the expansion tank as illustrated in Figure 12.
2. Connect and clamp the overflow tubing from the expan-
sion tank to the Aqua-Hot’s expansion tank connection.
Reference Figure 12.
3. Drill a hole in the bay floor and connect (secure with a
clamp) a long enough piece of overflow tubing so that it
can be connected to the top of the expansion tank and
extend through the bay floor.
Figure 12
— Page 15 —
NOTE: The top of the expansion tank should always be
mounted at least four inches higher than the highest
point on the Aqua-Hot’s boiler tank.
NOTE: Avoid dips and bends in the overflow tubing from the
Aqua-Hot to the expansion tank as air can become
trapped in these dips and bends, preventing the expan-
sion of the heating solution from properly depositing
in the expansion tank.
CAUTION:
The Aqua-Hot tank and heating loop operate at
0.0 psi (zero pressure system). Air pressure ap-
plied to the tank MUST NOT exceed 20 psi. Ex-
cess pressure will result in internal damage.

© 2011 Aqua-Hot®375-D Installation Manual
• Reference Figures 14, 15, 16, and 19 for mounting
location information.
•Reference Figure 14 for clearance information.
SECTION 3: HYDRONIC HEATING SYSTEM
Mounting Requirements:
• Sufficient ventilation (return-air) must be supplied
to each interior heat exchanger. Reference Figures
15 and 16.
Figure 13
Figure 14
Figure 15
— Page 16 —
Indicates sample mounting locations for the Cozy heat exchangers. Actual placement and quan-
tity vary based on the individual design of the coach. For specific design assistance, contact
Aqua-Hot at 303-659-8221
NOTE: An accessory device is available for the Cozy Heat
Exchanger for the purpose of redirecting the airflow
from the heat exchanger. Reference Figures 17 and
18.
NOTE: In order to achieve the best heating results, place the
heat exchanger as close to the floor of the plumbing
bay as possible (heat will naturally rise).
NOTE: Mounting the heat exchangers without sufficient ven-
tilation will severely reduce their overall heating per-
formance (heat output).
In order to provide sufficient ventilation, the return-
air registers must be the same size, or larger, than the
outlet-air registers.
Return-air must be supplied from the corresponding
interior heating zones.
Heat Exchanger Locations and Clearances:
• Place the heat exchangers so that even heat distribu-
tion will be felt throughout the interior of the mo-
torhome. Reference Figure 15.
•Place the heat exchangers where they will be acces-
sible for potential servicing and cleaning.
• Centralize and position a heat exchanger in the fresh
water storage tank plumbing bay. Reference Figure
13.
NOTE: For single slide-out configurations, it is usually sim-
plest to place a heat exchanger on the opposite side of
the motorhome pointing towards the slide-out.

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 3: HYDRONIC HEATING SYSTEM
Mounting the Heat Exchangers:
1. Cut out a 2.5 inch H x 10 inch W opening for each heat
exchanger outlet and cold-air return register. Reference
Figure 21.
2. Mount each heat exchanger permanently into place.
3. Install the hot-air outlet and cold-air return registers.
Reference Figure 16.
If the toe-kick areas in the motorhome are inadequate to
house a heat exchanger for regular installation, a plenum
may be used on the heat exchanger, which can be used with a
smaller vent as seen in Figure 18. The plenum allows only
the desired outlets to be opened by removing the metal insert
on the vent.
Figure 16
Figure 17
Figure 18
— Page 17 —
Vent installed
In toe-kick area
Cozy Heat
Exchanger
Hose to direct
air to vent
Toe Kick
Board
Plenum
NOTE: Please note that a return-air register may not be re-
quired; however, adequate return-air must be pro-
vided to each particular heat exchanger. This means
that the total cross-sectional area of the return-air
opening must be equal to or greater than the cross-
sectional area of the hot-air outlet opening of the heat
exchanger.

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 3: HYDRONIC HEATING SYSTEM
Figure 21
— Page 18 —
Figure 20

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 3: HYDRONIC HEATING SYSTEM
— Page 19 —
Figure 19

© 2011 Aqua-Hot®375-D Installation Manual
SECTION 3: HYDRONIC HEATING SYSTEM
Wiring the Heat Exchangers:
1. Within each heating zone, run an 18-gauge wire - black
for negative, from each heat exchanger’s black wire to
the chassis ground source. Reference Figure 23.
2. Within each heating zone, run one 18-gauge - red for
positive, from the heat exchanger farthest from the Aqua
-Hot past all other heat exchangers in that zone to the
terminal block.
3. Within each heating zone, connect the red heat ex-
changer wires to the 18-gauge wire ran in step 2. Be
sure that the wire end (farthest from the Aqua-Hot) is
either attached to the last heat exchanger or covered to
prevent additional connections.
4. Attach each zone wire ran in step 2 to the Aqua-Hot
terminal block - position F1 for zone 1 and position F2
for zone 2. Reference Figure 22. Tighten the screw in
the terminal to secure the wire in place.
5. Label the wires indicating the heating zone they pertain
to (e.g., Living Room, etc.)
Figure 23
— Page 20 —
Terminal Block for Switches, Heat Exchanger
Fans, and Thermostats
Terminal for Heating
Zone 1’s positive heat
exchanger wire (F1)
Terminal for Heating
Zone 2’s positive heat
exchanger wire (F2)
Figure 23
NOTE: It is recommended that the wire numbers in Appendix
A be used when installing the Aqua-Hot in order to as-
sist with differentiating between the separate heating
zones and to aid service personnel with troubleshooting.
Figure 22