Aqua-Hot 100 Series User manual

Installation Manual
AHM-125-D02
DIESEL
100SERIES

Introduction
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 1
Contents
Caution Notes...............................................................................1
Installation Checklist ...................................................................2
Introduction ..................................................................................3
System Features ..........................................................................6
Component Cut-Aways .................................................................8
Installing the Aqua-Hot ..............................................................10
Interior Components ..................................................................11
Heat Exchangers ....................................................................... 13
Mounting the Burner to the Vehicle..........................................15
Combustion Air & Exhaust System............................................17
Fuel System ................................................................................19
Plumbing the Heating Zone...................................................... 22
Plumbing Example .................................................................... 23
Domestic Water System.............................................................24
Connecting the M125D to 12V DC Power ............................... 25
Burner Harness ......................................................................... 26
Coach-Side Harness & RV-C ......................................................27
Connecting the Aqua-Hot to AC Power..................................... 28
Conguring the Zones............................................................... 29
Filling the Aqua-Hot................................................................... 30
Fuel System Fill Procedure ........................................................31
First Operation........................................................................... 32
Winterizing................................................................................. 34
Appendix A: System Schematics...............................................37
Appendix B: Measuring Antifreeze........................................... 39
Appendix C: Parts & Accessories ............................................. 40
Warranty .................................................................................... 46
Caution Notes
Caution Notes
As you read this information, take particular note of the NOTICE,
CAUTION, WARNING, and DANGER symbols when they appear.
This information is important for safe and efcient use of the
Aqua-Hot system.
NOTICE signals a situation where potential damage to the
Aqua-Hot could occur.
CAUTION signals a situation where potential harm or risk
of minor or moderate injury could occur if you do not follow
instructions.
WARNING signals a hazardous situation where potential harm,
risk of serious injury, or death could result if instructions are
not followed.
DANGER signals a situation where immediate risk of serious
injury or death will result if instructions are not followed.
NOTE: This manual will also use notes sections similar to
this one to draw attention to features and practices which
must be observed.

Introduction
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 2
Installation Checklist
Completed Description Page No.
Aqua-Hot & Interior Components Installed 10-12
Cozy heat exchangers installed 13-14
Diesel Burner Mounted to Vehicle 15
Diesel Burner Combustion Air & Exhaust System Installed 17-18
Fuel stand pipe/adapter installed in vehicle fuel tank 19
Fuel lines and connectors properly installed 20
Heating Zone plumbed 22
Domestic Water System plumbed to the Aqua-Hot 24
12VDC connected to Aqua-Hot 25
Diesel Burner & Coach-Side Harness connected to Aqua-Hot 26-27
120VAC connected to Aqua-Hot 28
Heating Zones congured on LCD 29
Aqua-Hot lled with proper mixture of ethylene glycol/water
heating solution 30
Fuel system properly purged before burner operation 31
First operation properly performed 32
Introduction:
The following table is a checklist of important items that need
to be completed for a successful install of the M125D Aqua-
Hot heater in your RV. Please conrm each item is properly
completed before utilizing the Aqua-Hot heating system.
Should additional assistance be needed, please contact the
Technical Support team at 574-AIR-XCEL (574-247-9235),
Monday through Friday, between 7:00am and 4:00pm MST.
You can also email the service department at servicedept@
aquahot.com.
All vehicle installations must comply with the requirements
listed in the Recreational Vehicle Industry Association’s
(RVIA) ANSI/NFPA 1192 Handbook for Recreational Vehicle
Standards.
WARNING!
Read and understand all instructions before installing the
Aqua-Hot unit and the external diesel burner. Aqua-Hot Heating
Systems is not liable for damage resulting from failing to
follow instructions contained in this, and any other Aqua-Hot
documentation relevant to this unit.
Improper installation, adjustments, service and maintenance
can cause personal injury or loss of life. Reference the
installation and user manuals before installation or service.
Contact your authorized service center or Aqua-Hot Heating
Systems if you have any questions before starting installation.
If the information in this manual is not followed
exactly, a re or explosion may result, causing
property damage, personal injury, or death.

Introduction
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 3
Read all instructions before installing the Aqua-Hot unit and
the external diesel burner. Aqua-Hot Heating Systems is not
liable for damage resulting from failing to follow instructions
contained in this, and any other Aqua-Hot documentation
relevant to this unit.
• Read this manual before installing or using the Aqua-Hot
System to reduce the risk of injury to persons or damage to
the equipment.
• The product identity label contains specications of the
unit, to what standards it has been tested, and important
safety notices.
• Disconnect electric wiring to the Aqua-Hot System before
welding or plasma cutting the RV to avoid damage to
equipment.
• The Aqua-Hot tank and heating loop operate at 7.0 PSI.
Maximum testing air pressure to the tank must not exceed
18 PSI. Exceeding this rating will cause internal damage to
the Aqua-Hot.
• Use caution when working on or near any propane/diesel
fuel system.
• DO NOT connect the 12-volt DC power to the Aqua-Hot if the
vehicle requires welding.
• At maximum operating temperature, the coolant will be very
hot and scalding. Hot vapor or coolant may cause serious
burns or injury. Be aware of hot surfaces.
• Use special caution when children are present. Children
must not be allowed to play with the heater or perform
cleaning and maintenance.
• Installation and repairs may only be carried out by an
authorized, factory-trained Aqua-Hot technician. The
heating system must be installed in accordance with local
codes, or in accordance with the Standard for Recreational
Vehicles, (RVIA) ANSI A 119.2/NFPA 501C, NFPA 1192.
• At maximum operating temperature, the hot air outlet will
be very hot that may result in serious burns or injury. Be
aware of hot surfaces.
• The diesel burner must be installed in a location that is
closed off from living quarters and accessible only from the
exterior of the vehicle.
• The burner produces very hot temperatures that can ignite
surrounding ammable materials. The burner should be
turned off when loading or unloading ammable materials.
If the information in this manual is not followed
exactly, a re or explosion may result, causing
property damage, personal injury or death.
Safety Features
Low-Voltage Shutdown
The Aqua-Hot Controller is designed to operate between
11V DC and 16V DC. If the Controller detects that it is
receiving voltage below 11.8V DC, a System Voltage fault
will trigger a display on the LCD screen. If the Controller
system drops below 11.2V DC for 30 seconds, it will
discontinue operation of the Aqua-Hot heating system.
Over-Current
An Over-Current fault condition occurs when too much
current is drawn by a component, usually a fan or pump.
When this fault is triggered, the output channel is shut off
until the system has been reset or power-cycled.
Over-Temperature
An over-temperature fault will occur if your Aqua-Hot heating
system has reached 218° F. The Controller will deactivate
the heater and display an over-temperature fault on the
LCD display screen.
Low-Level Cutoff
If the system senses low uid levels, the heating system will
shut down all fans, heat sources, and pumps until the unit
is adequately relled.

Introduction
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 4
As with any appliance, allow the Aqua-Hot to
completely shut down BEFORE disengaging
the RV 12V power disconnect.
Safe Installation of the Diesel Burner
Be sure to become familiar with the installation process and the
documentation before installing in the vehicle.
• Make sure to protect the burner during installation. Do not
drop or stand on the burner.
• Avoid abruptly shutting down the burner prior to the purge
cycle. The burner fan will continue to run for several minutes
after being shut off to cool down and purge unused fuel.
• Only turn off the burner at the control panel in the interior
of the vehicle.
• Do not disconnect the 12V DC power supply prior to the
purge cycle.
• Only shut down the burner via the battery disconnect in the
case of an emergency or danger.
• Do not allow the wiring or wiring harness to come into
contact with sharp edges on metal panels. The wires can
become damaged and short circuit and potentially cause a
re. Use caution when installing the wiring.
• Protect any vehicle parts near the burner from excessive
heat damage, or from contamination from fuel.
• Make sure the internal combustion burner will not pose
a re hazard even in an overheat situation. Take care in
placing the burner with enough space from vehicle parts
and that the burner will have ample ventilation.
• The serial label must be visible and legible after the burner
has been installed.
• All precautions must be taken to minimize the risk of
personal injury or damage to the burner or vehicle.
• It must be obvious to the user when the burner is switched
on or off.
• The burner may not be mounted in a position above the
M125D tank.
Fuel Supply
• Do not use the heater in enclosed spaces such as a garage.
The fumes produced from the exhaust can be toxic. Do not
use the burner while refueling or while other appliances are
being serviced or refueled.
• The fuel ller neck should be installed in a compartment
that is closed off from living quarters and must have a
tightly tting cap to prevent any fuel leaks.
• A visible, legible sign must be attached to the ller neck that
the burner be turned off before refueling. A similar warning
is included in the manufacturer’s operating manual.
• The diesel fuel lter is to be replaced every year for optimal
performance.
Exhaust System
• Do not operate the burner in an enclosed space or a space
that does not have exhaust ventilation. Fumes from the
exhaust may be toxic.
• The exhaust system must be positioned so that the fumes
will not get into the interior of the vehicle through ventilation
openings or windows.
Combustion Air Inlet
• The burner combustion chamber air must not be taken from
the interior of the vehicle, only fresh air from the exterior.
• An intake line is required for the combustion air.
• The air inlet must be positioned in an unobstructed manner.
NOTE: Aqua-Hot recommends regular exercise of the Aqua-
Hot heating system to avoid issues with starting after a
several-month idle period.
Do NOT shorten the burner harness. Shortening the
burner harness can cause improper operation and/
or damage to the system.

Introduction
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 5
System Overview
The Aqua-Hot M125D is a Hydronic Heating System that can
provide heat and hot water on demand using a built-in electric
heating element and an external diesel burner.
The Aqua-Hot Heating is a 2-in-1 System
1. Interior heating system: provides quiet, comfortable
interior heat and even temperatures.
2. Tank-less hot water system: provides a ow of
comfortable hot water.
The Aqua-Hot heating system heats an ethylene glycol based
antifreeze and distilled water solution that is stored in the Aqua-
Hot’s boiler tank. This uid solution must be up to operating
temperature before the Aqua-Hot will provide interior heat or hot
water. The tank-less hot water system produces approximately
0.8 GPM of hot water.
To get the Aqua-Hot to temperature, turn the electric heating
element and/or the external diesel burner to the “ON” position
on the Aqua-Hot LCD screen (shown below), or on the RV
control panel. It may take up to 20 minutes to get to operating
temperature before heat or hot water are available.
For continuous hot water or heat in colder conditions, it is
recommended to utilize the external diesel burner. The electric
heating element will provide heat only in mild conditions and
provide light duty hot water needs.
Should additional assistance be needed, please contact the
Technical Support at 574-AIR-XCEL (574-247-9235), Monday
through Friday, between 7:00am and 4:00pm MST.
Important Notes:
• A qualied installer or service technician must perform
equipment installation or service. Contact Aqua-Hot for
Factory Authorized Service Centers or Certied Technicians
located near you at www.aquahot.com/service-help, or call
us at 574-AIR-XCEL (574-247-9235).
• Warranty work must be performed by an Aqua-Hot
Authorized Service Center.
• Your on-product identity label contains the specications of
your unit. Factory settings may be adjusted by the vehicle
manufacturer, conrm nal setting with your dealer.
• This heating system has been certied for installation only
in recreational vehicles, not certied for use in boats.
• The Aqua-Hot heating system operates independently of
the vehicle engine and is connected directly to the electrical
system of the vehicle. The diesel burner is only connected
directly to the fuel system and the battery of the vehicle.
• Please read this manual and follow instructions to avoid
injuries during installation and/or operation.
Heat Priority Option:
The Aqua-Hot comes equipped with a three-way valve
(sometimes known as the summer/winter valve). This controls
the ow of the antifreeze and water heating solution within the
Aqua-Hot to deliver either hot water or interior heat as priority.
Tapping on this element will change the valve’s orientation.
When this element is activated, it overrides the automatic
function and orients the valve to interior heat. When the element
is not activated, the unit is in automatic mode and the valve is
automatically oriented based on the Low-Temperature Cut-Off.

System Features
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 6
NOTE: This product label is attached to the side of the
Aqua-Hot, and provides a ready reference to specications,
test standards, and important safety notices.
System Specications
Electric Element
Power Consumption......................................1500 W (maximum)
Voltage ..............................................................................110V AC
DC Power
Power Consumption.......................................... 57 W (maximum)
Zone Heat Circulation
Pumps...........................................................................................1
Power Consumption (max)............................................20W/1.7A
Voltage ............................................................................... 12V DC
Interior Heating
Maximum Heating Zones.............................................................3
Cozy....................................................... 6W/0.5A - 8,000 BTU/hr
Whisper............................................4.5W/0.37A - 4,000 BTU/hr
H.E. II................................................... 3W/0.25A - 4,000 BTU/hr
Domestic Water Heating
Maximum......................................................................... 0.8 GPM
Physical Specications
Dimensions (US)...............................15.38”L x 7.90”W x 9.66”H
Dry Weight ............................................................................42lbs.
Wet Weight............................................................................60lbs.
NOTE: Control Panel “Quiet Mode” reduces heat exchanger
power consumption by 20%
All vehicle installations must comply with the requirements
listed in the Recreational Vehicle Industry Association’s
(RVIA) ANSI/NFPA 1192 Handbook for Recreational Vehicle
Standards.
Figure 1

System Features
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 7
System Specications
Diesel Burner
Heat Flow...............................................5,188 to 17,060 BTU/hr
Diesel Fuel Consumption...............................0.07 to 0.16 gal/hr
Coolant Pump................................................................20W/1.7A
Operating Pressure (med heat)....................................36.25 PSI
Flow Rate (minimum).....................................................36.25 PSI
Working Altitude .............................................................. 16,000ft
Fuel
Fuel Type............................................................................DIESEL
Fuel Consumption (Low Output)...................................... 0.07g/h
Fuel Consumption (High Output)..................................... 0.16g/h
DC Power
Consumption .................................................................10 to 37W
Operating Amp Range............................................... 0.83 to 3.8A
Operating Temperatures
Burner Operation ..................................................... -40 to 176°F
Burner Storage................................ .........................-40 to 248°F
Fuel Pump Operation ................................................. -40 to 86°F
Fuel Pump Storage...................................................-40 to 194°F
Physical Specications
Dimensions................................................ 8.8”L x 3.4”W x 6.9”H
Weight ..................................................................................6.3 lbs
TECHNICAL SPECIFICATIONS
Heating Medium Ethylene Glycol/Distilled Water
Thermal Power (W)
High Power Operation: 5000W
Low Power Operation: 2400W
Fuel DIESEL
Fuel Consumption
(gallons per hour)
Low power operation: 0.07 g/h
High power operation: 0.16 g/h
Power supply (battery for
the engine) DC12V
Power Consumption (W)
At start <100 W
High power operation: 37 W
Low power operation: 10 W
Working pressure (MPa) 0.25
Lowest working
temperature -40°F
Net Weight (heater only) 10.6lbs
Working height
(above sea level) 16,405 ft
Weight of Main Heater 6.3lbs
Temperature of Coolant
when blower is started 113°F
Figure 2
NOTE: This product label is attached to the top of the
burner and provides a ready reference to specications,
test standards, and important safety notices.
All vehicle installations must comply with the requirements
listed in the Recreational Vehicle Industry Association’s
(RVIA) ANSI/NFPA 1192 Handbook for Recreational Vehicle
Standards.

Component Cut-Aways
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 8
1211
7
2
3
8
1
6
4
5
10 9
20
19
Figure 5
Aqua-Hot M125D Heating System
1. Heating Solution Tank
2. Plate-to-Plate Heat Exchanger
3. Tempering Valve
4. Three-Way Valve
5. Cozy Heat Exchanger
6. Burner Circulation Pump
7. External Diesel Burner
8. Fluid Circulation Pump
9. Coolant Out
10. Coolant In
11. Aqua-Hot Controller
12. LCD Screen
13. AC High-Limit Thermostat
14. Float Switch
15. AC Activation Relay
16. Fluid Fill Port w/ Radiator Cap
17. Tank Temperature Sensor
18. AC Electric Element
19. Domestic Cold-Water Inlet
20. Domestic Hot-Water Outlet
Figure 4
Figure 6
Figure 3
17
13
1816
14
15
FRESH WATER
FROM RV WATER TANK
TO HOT WATER
FAUCETS

Component Cut-Aways
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 9
6
14
12
15
1
9
18
20
19
10
4
11
7
17
3
8
2
Figure 8
13
Figure 9
Figure 10
16
5
Figure 7
21
Belief Diesel Burner
1. Combustion Air Fan
2. Burner Outer Casing
3. Burner Inner Casing
4. Combustion Chamber
5. Glow Plug
6. Flame Sensor
7. Temperature sensor
8. Over-Heat Sensor
9. Burner Controller
10. Air Inlet Pipe
11. Mufer
12. Fuel Pipe
13. Coolant Pump
14. Fuse
15. Main Harness Connector
16. Fuel Pump
17. Exhaust Pipe
18. Coolant outlet Pipe
19. Coolant Inlet Pipe
20. Burner
21. Diesel Fuel Filter

Support and Clearance
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 10
Installing the Aqua-Hot
Install the Aqua-Hot in a compartment which protects the unit
and components, and allows service access to the Aqua-Hot.
Make the following considerations when supporting the Aqua-
Hot to ensure its most optimal operation and location.
1. Reference the following illustrations below for mounting
information.
2. Mock up the locations for the diesel burner and the Aqua-
Hot components. Ensure there is adequate room for
installation and service.
3. Identify the needed lengths of hose, insulation, wiring, and
the proper connectors to reach each component. Reference
Figure 11 and the parts list at the back of this manual.
Boiler Tank
Filler Neck
Coolant In Coolant Out
(4) #10 Screws
Expansion hose. Must vent to
the exterior of the vehicle
Hole in the RV bay oor for overow hose
90° or Straight
ttings
Figure 11
Push Mount
Zip Tie
90° Fitting & 4”
heater hose
Figure 12
Interior Components
Boiler Tank
• The boiler tank must be the highest point in the system.
• Ensure that the mounting location can support at least
50lbs and withstand sustained hot temperatures. The tank
should be the highest point in the system and be mounted
to a vertical wall.
• Use (4) #10 screws to secure the tank in place to the RV.
• The best place for the boiler tank is in a cabinet to prevent
accidental contact with hot surfaces, making sure there
is ample space to pour uid, route plumbing, and service
components.
Mounting the Boiler Tank (Figure 11)
1. Install barb adapters into the “Coolant In” and “Coolant
Out” ports on the bottom of the tank.
• 90° and straight ttings are supplied in the kit. Choose
the appropriate ttings for the application.
• Apply PTFE tape to tting threads before installation.
2. Using 4 screws, attach the tank to the mounting location.
Ensure the tank is level and no wires are pinched during
mounting.
3. Using the provided hose clamp, attach the provided
5/16
”
heater hose to the overow barb on the ller neck of the
boiler tank.
4. Route the overow hose through a grommeted and sealed
hole in the oor of the vehicle to the exterior.
Zone Pump Considerations
• Must be located below the level of the tank in a cabinet
or storage to prevent accidental contact with hot surfaces.
• Must be inside the vehicle and provide adequate space to
route plumbing lines without kinks or sharp bends.
• It is recommended to use the alternate mounting method
where space in the tank cabinet allows. The 90° barb
tting must be installed in the “COOLANT OUT” port when
using the alternate mount.
1. Slide the pump mount onto the pump.
• Orient the pump in the pump mount to simplify the
plumbing and ensure access to the electrical plug.
2. Screw the pump mount to the mounting location.
Alternate Mounting (Figure 12)
1. Wrap the provided arrowhead push mount zip tie around
the pump.
2. Position the arrowhead to align the pump ports in a
convenient direction for plumbing and tighten the zip tie.
3. Connect the “Coolant Out” port to the pump with a 4in
section of heater hose and two hose clamps.
4. Snap the arrowhead mount into the bracket on the bottom
of the tank.

Fluid Expansion Bottle
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 11
Plate to Plate Heat Exchanger
• Must be mounted on a vertical wall able to withstand
sustained temperatures of 180°F.
• Must be located below the level of the tank in a cabinet
or compartment to prevent accidental contact with hot
surfaces.
• “Glycol Out” and “Water In” ports at the top, “Glycol In” and
“Water Out” ports at the bottom.
• Use 4 - #8 Screws or larger.
Mounting (Figure 13)
1. Using 4 screws attach the exchanger to the mounting
location. Ensure the exchanger is vertically level.
2. Apply a hot surface warning decal near the mounting
location.
Tempering Valve
• Must be in a cabinet or compartment to prevent accidental
contact with hot surfaces.
• Mounting surface must be able to withstand sustained
temperatures of 180°F.
• In the event of an emergency pressure release, the valve
can emit scalding water. Ensure its location will allow the
valve to safely do so.
Mounting (Figure 14)
1. Using the provided P-clamps and two screws, attach the
valve to its mounting location. It may be helpful to leave the
screws loose until the domestic water system is plumbed
to the valve.
2. Apply a hot surface warning decal in an unobstructed
location near the valve.
Three-Way Valve
• Must be in a cabinet or compartment to prevent accidental
contact with hot surfaces.
• Mounting surface able to withstand sustained temperatures
of 180°F.
Mounting (Figure 15)
1. The provided P-Clamps use the coolant lines to mount the
valve. Choose a location and wait to mount the valve after
plumbing the system.
2. Apply a hot surface warning decal in an unobstructed
location near the valve.
Interior Components
P-Clamps
Figure 15
Three-Way Valve
P-Clamps
Pressure Relief Valve
Figure 14
Tempering Valve
GLYCOL OUT WATER IN
GLYCOL IN WATER OUT
Figure 13
Plate to Plate Heat Exchanger

Fluid Expansion Bottle
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 12
Interior Components
Aqua-Hot Controller
• Choose a location safe from dust and moisture.
• This component is rated for the heat generated by the
other Aqua-Hot components and can be in the same
compartment.
• Ensure enough space surrounding the controller to route
wiring with sufcient strain relief.
Mounting (Figure 16)
1. Using 4 screws, mount the controller in the chosen location.
LCD Screen
• All user inputs will be done at the LCD screen.
Choose an easy-to-access location that is safe
from damage during normal use of the vehicle.
• A cutout is needed in the mounting surface to
provide clearance for the back of the screen and
to route the RVC cable. There is a sticker with a
template for the cut-out.
Mounting (Figure 17)
1. Remove the bracket from the back of the LCD
screen. Note the orientation markings in the
corner of the screen and bracket.
2. Cut a hole in the mounting location for the bracket.
3. Using 4 small at head screws or rivets, attach
the bracket to the cabinet. Ensure the bracket is
oriented correctly.
K-Line Converter
• Choose a location safe from dust and moisture.
• This component is rated for the heat generated by the
other Aqua-Hot components and can be in the same
compartment.
• Ensure enough space surrounding to route wiring with
sufcient strain relief.
Mounting (Figure 18)
4. Using 4 screws, mount the K-Line Converter. Figure 18
Figure 17
LCD Screen & Bracket
K-Line Converter
Figure 16
Aqua-Hot Controller
LCD FRONT
2.50
3.64
2.45
3.65
TOP
Ø 0.15”
(x4)
4.05
2.84
NOTE: All measurements are in inches.
BRACKET BACK

Installing Heat Exchangers
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 13
Heat Exchangers
• Cozy heat exchangers can be mounted either at on the
ground or vertically, and as close to the oor as possible
for best performance, in an area where it can be easily
accessed for maintenance. Reference Figure 19.
• Supply ventilation cross-sectional area of at least 29in2
must be supplied to each heat exchanger.
• Do not supply heat exchangers air that is drawn from the
bay areas. Return air should be drawn from the same room
the heat exchanger is heating.
• The heating air supply may be fresh or recirculated air
that is drawn from a clean area that is not likely to be
contaminated with exhaust or other toxins.
• Coolant must ow in through the bottom of the heat
exchanger, and out the top (Figure 23).
• The AHM-125D is designed to work with up to 3 thermostatic
heating zones and a maximum of 3 Cozy’s. Two Whisper
exchangers can be substituted for one Cozy.
• Position the heat exchangers so that even heat is distributed
throughout the RV interior. The rst heat exchanger on the
loop will output the most interior heat.
• If a heat exchanger is kept in the freshwater storage bay,
the last heat exchanger in the coolant loop should be used
(see Figure 20).
• It is not recommended to place a heat exchanger on the
slide-out section of any vehicle due to the high probability
of damage occurring to the heating loop from moving parts.
Vertical Orientation
Horizontal Orientation
Figure 19
Figure 20
Heat Exchanger Installation Requirements
Figure 21
RV/Bay Floor

Locations and Clearances
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 14
Heat Exchangers
Heat Exchangers
1. Cut out a 2.5” x 10” opening for each heat exchanger outlet
and cold-air return grate as shown in Figure 22.
2. Mount each heat exchanger permanently into place. There
are 4 tabs on both sides - see Figure 23.
3. Install the hot-air outlet and cold-air return grate.
A minimum of supply ventilation cross-sectional area of at least
29in2 (74cm2) must be supplied to each heat exchanger.
Figure 22
Mounting
Tabs (both
sides)
Inlet
Outlet
Figure 23
Thermistors
• Choose locations that accurately reect the temperature of
the zone.
• Each zone requires one thermistor.
• A thermistor can only operate one zone.
○ Multiple cozy’s can be in the same zone.
• Mounting at eye level, where possible, will provide the most
accurate reading.
• Avoid locations that will frequently be in direct sunlight.
• Avoid locations close to windows and doors.
Mounting
1. Choose a location for the thermistor.
2. Drill the two mount holes and a third hole for the wires.
Attach the thermistor using two fasteners.
Thermistor
Figure 25
Figure 24
Inlet
Outlet
PEX Insert Hose
Clamps ¾”
Coupler

Locations and Clearances
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 15
Mounting the Burner
Install the external diesel burner in a location separate from
the living spaces that protects the unit, and also allows service
access to the burner.
• Reference the illustrations below for mounting information.
• The burner is best placed in a location where it can be
easily accessed for service and maintenance.
• The burner must not be mounted higher than the tank.
• The bracket must be secured to the vehicle with at least 4
M6 screws.
• Fasten the burner bracket rmly, the 4 corners should be
lined with rubber shock absorbers.
• The burner can be oriented to suit different orientations/
positions, however it should not exceed an angle greater
Before drilling holes in the vehicle, consult the
manufacturer for recommendations and limitations.
Do NOT weld to the vehicle frame.
Figure 27
(4) M6 Bolts
Mounting Bracket
Figure 29
Figure 26
Ø 0.52in (x4)
Mounting Bracket Dimensions
4.85”
5.28”
6.125”
5.65”
than 90°. The recommended orientation is horizontal with
the exhaust pipe vented downwards.
• If mounting to the frame rail, use (4) M6 bolts. Drill (4) M6
holes where the burner will be mounted, and fasten the
bracket to the vehicle with (4) M6 nuts.
• Secure the burner to the bracket using appropriate
mounting hardware, M6*95 bolt torqued to 6 lb-ft.
Mounting the Burner to the Vehicle
Figure 28
(1) M6-95 Bolt

Locations and Clearances
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 16
Star Bushing
Rotating Coolant Fittings
1. Remove the 6 bolts on the coolant tting retaining plate.
2. Wiggle each tting while carefully pulling up to release the
ttings from the casting.
3. Flip the retaining plate over and locate the star bushing
used to align the ttings.
4. Press the tting from the top of the plate to disengage the
star bushing.
5. Rotate the tting to the correct orientation.
6. Press the star bushing and tting back into the retaining
plate.
7. Replace the retaining plate and ttings onto the burner.
Ensure the ttings align with the ports in the burner casting.
8. Wiggle each tting while pressing them into the casting
ports.
• Lubricate the O-rings with coolant.
9. Reinstall the 6 bolts attaching the retaining plate to the
burner.
Mounting
1. Using the 4 provided M6 bolts and M6 nuts,
fasten the burner bracket to the mounting
location. If different bolts are required, ensure
they are M6 or larger.
2. Position the burner onto the bracket making
sure the tabs of the bracket engage the
grooves on the burner.
3. Align the mount hole on the burner with the
threaded hole on the bracket and install the
provided M6 x 95mm bolt.
Burner Pump
• Choose a protected location near the burner. The pump
wire harness from the burner must be able to reach the
pump.
• Position the pump to simplify plumbing to the burner.
Mounting
1. Locate the coolant pump. The pump mount should be
attached to the pump.
2. Using the provided self-drilling screw, attach the pump
to the mount location.
Burner Top Retaining Plate
90°
Figure 30
Figure 31
Figure 32
Figure 33
Circulation
Pump
Diesel Burner
Supply Port
Diesel Burner
Hose Clamps
Mounting the Burner
90°

Locations and Clearances
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 17
The combustion air should not be supplied from living areas.
The air intake opening must not point in the direction of travel.
It also should be free from potential clogs from snow, debris, or
water.
• Installation of air intake and exhaust system is shown in
Figure 35.
• The intake silencer does not act as a lter. Choose a
location which limits exposure to dust and moisture.
• Limit opportunity for vehicle or burner exhaust to be drawn
into the burner.
• The intake must not point in the direction of travel.
• The intake tube must not be longer than what is included.
Mounting
1. Using the provided hose clamps, attach the open end of the
intake tube to the intake port on the bottom of the burner.
2. On the other end of the tube, remove the metal cap.
3. Cut the tting on the silencer to the appropriate size for the
intake tube.
4. Thread the silencer into the intake tube.
5. Using the provided silencer mount bracket, mount the
silencer to the chosen location.
6. Secure the intake tube where convenient to prevent rubbing
and abrasion.
NOTE: The air intake tube cannot be installed downward. A
water drain hole (Ø 2-5) is to be made at the lowest point.
The tube should be installed in a position that stays as cool
as possible and protected from splashing water.
Combustion Air System
The combustion air intake may be installed in the same
compartment as the vehicle’s fuel tank, but the air intake must
come from the exterior. The exhaust must be routed to the
exterior and any holes must be splash-proof.
NOTE: Should this particular application require modication, please contact Aqua-
Hot Heating Systems at 574-AIR-XCEL (574-274-9235) for further assistance.
Figure 35
Figure 34
Combustion Air Connection
BURNER AIR CONNECTION
Combustion Air System
7
1Burner
2Air Inlet Pipe
3Exhaust Pipe
4 Mufer
5Exhaust Tail Pipe
6 Protective Hoods
7Protective Hoods
8Air Filter
543268
1
NOTE: The exhaust pipe has a slit
on one end that needs to connect
to the burner. The slit will allow the
clamp to tighten properly on the
burner.
A similar slit may be cut into the
end of the tube connecting to the
mufer if it will not tighten properly
on the burner. See page 18 for
more information.

Locations and Clearances
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 18
Instructions
1. Plan where the mufer will be located.
2. Make the appropriate cut in the exhaust tube ensuring one
section can reach the burner and the remaining tube can
safely terminate beyond the vehicle.
3. Using the provided mufer bracket, attach the mufer to
the chosen location.
4. Using the provided clamps, attach the rst section of tubing
to the burner exhaust port and one end of the mufer.
5. Using the provided clamps, attach the second section of
the tube to the opposite end of the mufer.
6. Using the provided exhaust hangar, attach the remaining
end of the tube to the vehicle close to the end of the tube.
7. The remaining exhaust hangar can be used to support the
exhaust tube in another location.
The specications and requirements must be followed carefully.
Failure to follow instructions may result in improper and unsafe
operation of the M125D and burner. Please comply with all
applicable legal requirements.
• Reference the diagram in Figure 35.
• The exhaust can reach upward of 500°F.
• Ensure there is no contact with temperature sensitive
parts. Leave at least a 1” air buffer between the exhaust
and any parts of the vehicle.
• Never terminate under the vehicle, a window, or any vents.
• Never extend more than ⅜” past the vehicle’s body.
• Never add more than 270° of cumulative bends.
• The total exhaust length must not exceed 3’ - 9”.
• Never point the exhaust straight down or close to the
ground.
• Ensure the mufer drain hole is pointing down.
Refer to the “Internal Combustion Engine Exhaust and Vehicle
Wall Openings” in RVIA’s ANSI/NFPA 1192 Handbook for
Recreational Vehicle Standards, as well as the National Fire
Protection Association’s (NFPA) 1192 Standard on Recreational
Vehicles for relevant information.
Exhaust System
Figure 36
Exhaust Pipe - Stainless Steel
The direction of the exhaust outlet must directed away from
any heat sensitive or highly ammable parts. Failure to do
so will result in a re. Exhaust cannot be routed through the
interior of the vehicle, only the exterior. Failure to do so can
cause exhaust gas to leak inside the vehicle causing illness
and/or death.
Exhaust System
Figure 37
NOTE: Exhaust parts are at high temperatures when the
heater is operating. They shall be installed far away from
plastic parts and wires of the vehicle to avoid damage. The
air inlet pipe and exhaust pipe can freeze easily in working
conditions and should be checked regularly for obstructions.
NOTE: The exhaust pipe has a slit on one
end that needs to connect to the burner. The
slit will allow the clamp to tighten properly on
the burner.
A similar slit may be cut into the end of the
tube connecting to the mufer if it will not
tighten properly on the burner. Reference
the image to the right and Figure 37.
Exhaust
Connection
BURNER EXHAUST CONNECTION
Slit in Exhaust
Pipe

Locations and Clearances
©Aqua-Hot® AHM-125-D02 Installation Manual REV221202 p. 19
Fuel Pump
• Choose a location that meets the requirements detailed in
Figure 38 & Figure 42.
• Install away from hot exhaust pipes and combustion gases.
• Protect against impact, dirt, and moisture as much as
possible and ensure adequate space for plumbing and
electrical connections.
• The outlet of the fuel pump is required to be installed
upwards. The angle should be between 15°-35°.
Mounting
1. Using the provided fuel pump, install the pump to the
mount location.
Fuel System
Fuel Filter
• The fuel lter should be
installed before the fuel inlet
of the fuel pump. Make sure
orientation and position of the
lter is accurate with the ow
of fuel.
• It is recommended to replace
the lter once a year or after
extended period of non-use.
Fuel Pickup
Two options are included with the kit:
The SAE 7.89 fuel line adapter can attach directly to the
external burner fuel tap included on some fuel tanks
The fuel standpipe can be used where no fuel tap is
provided.
• Fuel must be drawn directly from the vehicle’s fuel tank.
• The M125 requires a dedicated fuel pickup that cannot be
shared with any other appliance.
• The end of the fuel pickup must sit 1.5 – 2” above the
bottom of the tank preventing the heater from consuming
all the fuel, stranding the vehicle.
Installing the SAE 7.89 Adapter:
1. Apply a small amount of gas to the rubber
seal inside the adapter.
2. Slide the adapter onto the fuel pickup until
a click is felt.
3. Gently pull on the adapter to ensure it is
locked in place.
Installing the Fuel Standpipe:
1. Drill a 6mm hole through the top of the fuel
tank. To make installation easier, place the
hole close to the fuel sending unit for the
vehicle. Prevent any chips and shavings from
falling into the fuel tank.
2. Cut the standpipe to length. Remove any
burrs and debris.
3. Slide the standpipe a short distance into
the hole. Slide the nut onto the standpipe
inside the tank and thread the nut onto the
standpipe threads.
• The standpipe nut must be installed from
inside the tank. The vehicle’s fuel sending
unit must be removed to gain access to the
inside of the fuel tank.
4. Tighten the nut making sure the standpipe port is aimed
correctly.
○
○
Figure 38
Figure 40
Figure 41
Fuel Pump Orientation
35°
1
2
min. 15°
0°
Allowable Installation Angle
Optimum Installation Angle
2
1
Figure 39
0-90°