Airxcel Aqua-Hot 100 Series User manual

Use and Care Guide
100Series
AHE-125-DN1

Journey in Comfort
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 1
Thank you for equipping your RV, coach, or caravan with an Aqua-Hot hydronic heating
system! We deeply value your business and we are grateful for the trust you have placed with
Aqua-Hot Heating Systems, LLC. Our customers are our top priority and we are committed to
providing best-in-class products, service, and support.
We understand how important comfort is to you as a recreational vehicle or manufactured
home owner; therefore, we have designed a heating system to signicantly improve all of your
comfort levels. Additionally, the Aqua-Hot hydronic heating system is a low-emissions, fuel
efcient system that adds thousands of dollars in value to your RV or home.
We know that you must be eager to get underway, but take time to read and understand this
Use and Care Guide to understand the basic functionality of the Aqua-Hot. This guide should
be maintained in legible condition and kept in a safe, accessible location for future reference.
Should you have any suggestions on how we can better serve you, please do not hesitate
to contact us.
Technical Support can be contacted at 574-AIR-XCEL (574-247-9235) . Hours of operation
are 7:00am to 4:00pm (MST) Monday through Friday.
The Aqua-Hot heating system is protected by the nest warranty in the industry (read about
it at the back of this manual).
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 Factory 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.
• Follow this guide exactly. Failure to do so may result in a re or explosion resulting in
property damage and/or personal injury.

IntroductionJourney in Comfort
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 3p. 2
Comfort Zone #1: Comfortable Cabin Heat.
Get heat where you want it, when you want it. This Aqua-Hot system puts heat where you need it. Therefore, your interior
temperatures will be just right. Don’t hesitate to crank up the heat because the Aqua-Hot system doesn’t remove moisture from
the air. From now on, you will have to blame the dry skin and itchy eyes on Mother Nature!
Comfort Zone #2: Quiet Operation
Say goodbye to rude awakenings from the forced air furnace, you’re an Aqua-Hot owner now! The Aqua-Hot is quiet when operating,
so you’ll never have to turn up the TV, yell across the room, or have an interrupted night of sleep again due to your heating system.
Comfort Zone #3: Comfortable Hot Water
Take showers knowing that your tank-less Aqua-Hot is ready and waiting to deliver hot water. The freedom to take a hot shower
when you want makes your experience much more like home.
Comfort Zone #4: Low Emissions
Aqua-Hot’s new low emission systems are fume-less and odorless. It’s good for you, good for your neighbor,
and good for the environment.
Comfort Zone #5: Large Service Networks
You won’t need to service your Aqua-Hot often, but when you do, you can be condent in our Certied Service Centers that are
close by and trained to assist you with all of your Aqua-Hot specic needs.
Comfort Zone #6: Adds Value
The NADA Recreational Vehicle Guide lists Aqua-Hot as adding thousands of dollars to the value of a coach or caravan. That value
will pay off when it’s time to trade up or sell.
Contents
Caution Notes.......................................................3
Safety Features ....................................................4
Component Call-outs ...........................................6
System Features ..................................................8
Operational Overview...........................................9
Aqua-Hot Layout ...................................................11
Operational Flowchart..........................................12
Maintenance Schedule........................................13
Winterizing the Aqua-Hot .....................................14
General Troubleshooting......................................15
Measuring Antifreeze Using a Refractometer ....16
Owner’s Service Log ............................................17
Warranty ...............................................................19
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.

Safety InstructionsSafety Instructions
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 5p. 4
Safety Features
Low-Voltage Shutdown
The 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 Controller 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 level, the heating system will
shut down all fans, heat sources, and pumps until the unit
is relled.
House Power Sense
The Aqua-Hot Controller contains within it a fail-safe
functionality known as House Power Sense. This
functionality serves as a live signal to the Aqua-Hot allowing
it to continue operating. If power is lost to the on-board RVC
network or other on-board control systems, the Controller
is signaled to shut down operation until a 12V DC power
signal is returned to the unit.
Read all instructions before using the Aqua-Hot unit. 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 user manual before 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 standard it has been tested, and important
safety notices.
• Disconnect electric wiring to the Aqua-Hot System before
welding or plasma cutting the coach to avoid damage to
equipment.
• The Aqua-Hot tank and heating loop operate at 0.0 PSI
(zero pressure system). Air pressure to the tank must not
exceed 18 PSI. Exceeding this rating will cause internal
damage to the Aqua-Hot.
• 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 result in
serious burns or injury. Be aware of hot surfaces.
If the information in this manual is not followed
exactly, a re or explosion may result, causing
property damage, personal injury or death.
As with any appliance, allow the Aqua-Hot to
completely shut down BEFORE disengaging
the coach 12V power disconnect.
• Use special caution when children are present. Children
must not be allowed to play with the heater or perform
cleaning and maintenance.
• At maximum operating temperatures, the hot air outlet will
be very hot that may result in serious burns or injury. Be
aware of hot surfaces.
• The burner produces very hot temperatures that can ignite
surrounding ammable materials. The burner should be
turned off when loading or unloading ammable materials.
Safe Operation
The Aqua-Hot Heating system consists of an electric
heating element and an external diesel burner. The
electric element and/or the external diesel burner
heat a glycol and water mixture, that ows through
tubing and into heat exchangers to heat a zone that
calls for heat. The heating system also heats domestic
water for hot water use in the shower or at hot water
faucets.
To safely and properly operate the Aqua-Hot 125DN,
please make sure that the uid level is up to the
“COLD” level line on the expansion tank before
heating. If the heater has already been activated and
running, the uid should be to the “HOT” level.
Locate the Aqua-Hot LCD screen (shown below)
inside the coach (contact the vehicle manufacturer if
unable to nd), tap the screen to wake, tap on either
the “ELECTRIC” to turn on the Electric Element or
“BURNER” to turn on the external diesel burner. It
will take approximately 20 minutes to get the glycol
uid up to operating temperature. After the tank is to
temperature, you can turn on the heat on your coach
thermostat or run hot water.
General Care
The Aqua-Hot 125DN’s uid levels should be checked
regularly to ensure it is at the proper level. It should be
checked when the Aqua-Hot is at maximum operating
temperature, when the external diesel burner completes a
cycle or when the electric element disengages. The level
should be at the “HOT” mark on the expansion tank.
It is necessary to take precautions during any user
maintenance. Note that the uid will be very hot, and any
scalding hot vapor or coolant could cause serious burns or
injury.
Intended Use
This manual explains the operation and care of the Aqua-Hot
heating system and Reporter.
These instructions are approved for the Aqua-Hot 125DN
model for recreational vehicles only. Not for use in boats.
Service and repairs may only be carried out by an authorized,
factory-trained Aqua-Hot technician. The heating system must
be installed/serviced in accordance with local codes, or, in the
absence of local codes, follow NFPA 1192.
• The vehicle owner is responsible for correct operation of
the appliance.
• The Aqua-Hot 125DN must comply with the codes and
regulations of the country it is being used in. National and
local codes must be followed, or follow NFPA 1192.
• Make sure to properly winterize the Aqua-Hot’s domestic
water system when not in use and/or any time the heater
is stored where freezing temperatures may be experienced.
The Aqua-Hot warranty will not cover claims for freeze
damage. Please refer to page 13 for proper winterization
of the Aqua-Hot.
• In order to provide the best freeze protection, boil-over
protection, anti-corrosion, and rust protection, a mixture
of 50/50 Ethylene Glycol antifreeze and distilled water
is recommended. The Aqua-Hot 125DN boiler tank holds
approximately 1.8 gallons.
• The mixture may be modied to provide the most adequate
freezing, boiling, and rust/anti-corrosive protection. A
50/50 mixture of Ethylene Glycol and distilled water has
a freeze point of approximately -35°F and a boiling point
of approximately 223°F. Reference page 16 for measuring
the antifreeze mixture with a refractometer.
Hot Water Priority System
The Aqua-Hot 125DN is a Hot Water Priority heating system.
Meaning that the 125DN cannot heat the interior of the coach
and produce hot water simultaneously. When hot water is being
used, the interior heating system will shut off temporarily, until
hot water is no longer being used.
When hot water is requested, domestic water from the
coach’s fresh water tank is transported through the domestic
water line, that goes into a heat exchanger located in the Aqua-
Hot. The water is then heated by the heated antifreeze and
distilled water solution. The heated domestic water then ows
through the tempering valve to be mixed with cool water from
the fresh water tank to achieve an appropriate temperature
before it ows to the faucet.
Figure 1

Component CalloutsComponent Callouts
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 7p. 6
1. Combustion Air Fan
2. Fluid Outlet
3. Fluid Inlet
4. Combustion Chamber
5. Circulation Pump
6. Exhaust Gas Temperature Sensor
7. Exhaust Outlet
8. Air Inlet
9. Control Unit
10. Burner Motor
11. Fuel Inlet
12. Combustion Air Inlet
13. Fuel Pump
14. High Altitude Bypass Assembly
1 32
5
Figure 8
5
13 2
11
6
9
10
7
Figure 7
4
10
9Figure 9
Figure 6
8
4
512
Aqua-Hot Diesel Burner
13
14
Figure 10
Aqua-Hot 125DN
1. Fluid Circulation Pump
2. Tempering Valve
3. Aqua-Hot Controller
4. Antifreeze and Water Heating Solution Tank
5. AC Electric Element
6. AC Activation Relay
7. Plate-to-plate Heat Exchanger
8. Three-Way Valve
9. Zone Air-Bleed Valve
10. Fluid Expansion Port (to overow bottle)
11. Zone Return
12. Fluid Fill Port
13. Zone Supply
14. Service Panel
15. External Diesel Burner Supply
16. External Diesel Burner Return
17. Domestic Cold-Water Inlet
18. Domestic Hot-Water Outlet
19. Domestic Low Point Drain
20. Cabinet Drain
12345
6 7 8 9
Figure 4
NOTE: The side panel in the view above has been made
transparent to aid in the explanation of the heater. DO NOT
remove the side panel. Doing so risks irreparable damage
to the Aqua-Hot. Only remove the service panel for service.
11
12
13
14
16
17
18
10
9
19
20
Figure 3
3
Figure 5
Figure 2
15

Activating the Aqua-HotAqua-Hot System Features
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 9p. 8
System Features
The Aqua-Hot 125DN Series 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 System 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 is powered by TribridHot™ technology and
uses one or a combination of the following heat sources:
• When plugged into shore power, or powered by a generator,
the electric element lets you use the power you are already
paying for to provide heat in mild conditions and meet your
light duty hot water needs.
• The external diesel burner can be utilized with the Aqua-Hot
to heat and produce hot water.
Bring the Aqua-Hot to Operating Temperature:
Your Aqua-Hot hydronic heating system heats an ethylene
glycol antifreeze and distilled water solution that is stored in the
Aqua-Hot’s boiler tank. This water and antifreeze solution must
be up to operating temperature before the Aqua-Hot will provide
interior heat or comfortable hot water. To bring the Aqua-Hot up
to temperature, navigate to the climate page of the LCD screen,
and tap either the “ELECTRIC” or “BURNER” icon. Depending
on the ambient temperature, it may take up to 20 minutes for
the Aqua-Hot’s water and antifreeze solution to reach operating
temperature.
Once the tank is up to operating temperature, the electric
element may be used to maintain the operating temperature
and provide light duty hot water and interior heat.
For continuous hot water, or for heat in colder conditions, it
is recommended to utilize the external diesel burner.
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.
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.
Electric Element:
The electric element is the Aqua-Hot’s secondary
heat source and can be used when plugged into shore
power. The electric element will work to maintain tank
temperature at 5°F below the heater activation threshold.
It can be activated by tapping on the ELECTRIC button of
the LCD screen interface.
The electric element has 2 modes: ON and OFF. When the
electric element is ON, the electric element will keep the
tank temperature between 165°F and 180°F. The electric
element will toggle between ON and OFF as needed, using
temperature readings from the RV interior thermistors. In
OFF mode, the electric element is off and will not provide
any heat to the Aqua-Hot tank.
Operational Overview
The heating features are powered by the external DC diesel
burner and/or the AC electric element on the 125DN. These
maintain the temperature of the Aqua-Hot’s antifreeze and
water heating solution to provide hot water and interior heat.
External Diesel Burner:
The diesel burner is the Aqua-Hot’s primary and most
powerful heat source, and provides all of the heating
and hot water needs when cold temperatures exist, and/
or when there is a high demand for hot water. It can be
activated by turning the burner on by tapping BURNER to
ON on the LCD screen shown below.
The burner has 2 modes: ON and OFF. When the burner
is ON, the burner will keep the tank temperature between
160°F and 180°F. The burner will toggle between ON and
OFF as needed, using temperature readings from the RV
interior thermistors. In OFF mode, the burner is off and
will not provide any heat to the Aqua-Hot tank.
Figure 11
Figure 12
Operational Overview

Activating the Aqua-HotActivating the Aqua-Hot
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 11p. 10
Heat Priority Option:
The Aqua-Hot comes equipped with the 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 as priority.
Tapping on this element will change the valve’s orientation.
When this element displays “INT. HEAT”, this valve is oriented
to provide interior heat by circulating the heating solution
throughout the interior heating zone. When the element says
“HOT WATER”, the valve is oriented so that the heating solution
is routed to prioritize hot water.
High Altitude Option:
The Aqua-Hot 125D comes equipped with a High Altitude
mode that allows the external diesel burner to operate properly
at high altitudes. It is recommended any time the coach is at
an altitude higher than 5,000 feet, to activate the High Altitude
button on the LCD screen. This modies the fuel pump rate to
decrease the ow of diesel fuel. This allows for less emissions,
carbon build-up, and proper diesel burner operation.
Controlling Heat Levels with Room Thermostat:
When the Aqua-Hot is on and up to operating temperature,
adjust the room thermostat to the desired temperature and it
will automatically activate the Aqua-Hot’s heating functions to
maintain the desired interior temperature.
Different manufacturers may use different types of thermostats.
Please contact the dealer or manufacturer for the exact type,
location, and thermostat operation.
Aqua-Hot LCD Display
The Aqua-Hot electronic display provides direct diagnostic and
control of the Aqua-Hot. This display is directly interfaced with
the Aqua-Hot to relay real-time operational information such
as unit diagnostics, warnings, faults, and operating conditions.
Please contact Aqua-Hot, or your vehicle manufacturer for more
information.
Figure 13
Figure 14
Figure 15
Operational Overview
Figure 17
Diesel Burner
Cozy #1
Living Space
Aqua-Hot
Heating System Cozy #2
Kitchen
Cozy #3
Bedroom
Cozy #1
Living Space
Aqua-Hot
Heating System
Figure 16
Diesel Burner
Cozy #2
Kitchen
Cozy #3
Bedroom
Aqua-Hot Layout

MaintenanceOperational Flow Chart
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 13p. 12
Operational Flow Chart
A heat source is selected from
Interior Switch Panel
Electric Element External Diesel Burner
Electric Heating Element
will activate, providing
heat to the antifreeze and
water heating solution
within the boiler tank
The diesel burner will
begin providing heat to the
antifreeze and water heating
solution present within the
boiler tank.
The antifreeze and water
heating solution in the boiler
tank heats to 180°F
An Interior Zone
Thermostat Calls
for Heat
A hot water faucet opens,
signaling a need for heat to the
boiler tank
The uid circulation pump
activates and begins circulating
the heated antifreeze and water
solution throughout the interior
heating zone
The heating zone
fans activate
Heat is transferred to the
vehicle interior via the heat
exchangers
The cooled antifreeze
is returned to the boiler
tank to be reheated.
Hot water ows from the water
faucet
Heat is transferred to the
domestic hot water system
Maintenance Schedule
Monthly Maintenance
Check the Aqua-Hot’s antifreeze and water heating solution to
ensure that it is at the proper level. This can be accomplished by
visually checking the coolant level in the Aqua-Hot’s expansion
tank; reference Figure 20 on page 15.
Please note that the coolant level should be checked ONLY
when the Aqua-Hot is at maximum operating temperature.
This should be done immediately after the electric element
disengages, or after the diesel burner has completed a cycle.
At maximum operating temperature, the antifreeze and water
heating solution should be at the level marked “HOT” on the
expansion tank.
It is also recommended to run the diesel burner once a month
for a full cycle (at least 20 minutes) to ensure optimum heater
condition.
Annual Maintenance
To maintain the Aqua-Hot at its full potential, it is highly
recommended to have the diesel burner tuned up annually. This
involves the fuel lter replaced, burner cleaned, inspecting the
exhaust and combustion air lines for damage and ensure they
are clear, checking the fuel lines for any leaks, checking the
hoses and wiring to make sure there is no damage or cracks.
Replenishing the Antifreeze and Water Heating
Solution
If the antifreeze and water heating solution needs replenishing,
remove the cap for the expansion bottle and ll it to the “HOT”
mark. Replace the expansion bottle cap when this is complete.
DO NOT operate the unit without rst replacing the cap of the
bottle. Reference Figure 20 for additional information. Excess
air will escape through this bottle as the stir pump of the unit
operates. While bleeding this system of air it will be necessary
to continue to ll the bottle until this process is complete.
Reference the Appendix on page 16 for the proper tool and
instructions for usage in measuring the system’s antifreeze
mixture ratio.
The Aqua-Hot does not need regular replacement of the
antifreeze and water heating solution, but in the event that more
antifreeze is required, contact Aqua-Hot Heating Systems to
purchase antifreeze, or for guidance in selecting an appropriate
antifreeze product for use with this unit.
When the Aqua-Hot is at maximum operating temperature, the
coolant is very hot. If the Aqua-Hot heating system is accessed,
scalding by hot vapor or coolant may occur. Before cleaning or
servicing, disconnect all power supplies.
DO NOT operate the external diesel burner and/or electric
heating element without antifreeze and water heating
solution present in the Aqua-Hot’s boiler tank. Doing so will
cause serious damage to the heater.
Overheat Protection
Every Aqua-Hot is equipped with at least two overheat
protection devices. These are commonly known as the high-
limit thermostats. These thermostats operate by maintaining a
circuit while the unit is below 218° F.
In the event of an overheat condition, the high limit
thermostats will cut the operating signal to the external
diesel burner, and/or the electric element. When this signal
is interrupted, the electric element and diesel burner will
immediately disengage. Contact Aqua-Hot Heating Systems
LLC for assistance in locating a qualied person to service this
heater.
In order to provide the best freeze protection, boil-over
protection, anti-corrosion, and rust protection, a mixture
of 50/50 ethylene glycol antifreeze and distilled water is
recommended. The Aqua-Hot 125DN boiler tank holds
approximately 1.8 gallons.
The mixture may be modied to provide the most adequate
freezing, boiling, and rust/anti-corrosive protection. A 50/50
mixture of ethylene glycol and distilled water has a freeze point
of approximately -35°F and a boiling point of approximately
223°F. Refer to the table below to determine the best protection
mixture ratio. Reference page 16 for measuring the antifreeze
mixture with a refractometer.
DO NOT attempt to reset the high-limit thermostats after
an overheat condition until the unit has been serviced by a
qualied technician. Failure to do so could result in damage
to the unit, personal injury, or death.
Freeze Point
(°F)
Concentra-
tion (%)
32 25 20 15 10 5 0 -10 -20 -30 -40 -50
010 16 21 25 29 33 39 44 48 52 56
Ethylene Glycol

Use and OperationWinterization
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 15p. 14
Winterizing the Aqua-Hot
The Aqua-Hot’s domestic water heating system must be
completely drained of domestic water at any time the heater is
stored where freezing temperatures may be experienced.
Please follow these instructions when winterizing the Aqua-
Hot domestic water heating system. Reference Figure 18 below
for a system overview.
1. Completely drain the fresh water storage tank.
2. Disconnect the domestic water demand pump suction line
from the fresh water storage tank.
3. Attach an adequate piece of hose onto the suction side of
the domestic water demand pump.
4. Place the opposite end of the hose into an adequate supply
of non-toxic RV winterization antifreeze (FDA certied as
GRAS must be used) and allow the uid to pump through.
5. Open and close all interior and exterior water faucets one
at a time, until ONLY pure RV antifreeze is present. Perform
this procedure for both cold and hot water faucets.
6. Remove the hose and reconnect the domestic water
demand pump’s suction line to the fresh water storage
tank.
NOTE: The Aqua-Hot can continue to be used for interior heat
once the domestic hot water system has been winterized. De-Winterization
To de-winterize the Aqua-Hot system, completely ll the fresh
water storage tank. Open and close the interior and exterior
faucets, one at a time, until only clear water is present.
Disinfecting the Domestic Water System
The Aqua-Hot Heating components are not compatible to
prolonged exposure to sodium hypochlorite (bleach or liquid
bleach.) Using products containing bleach, including water
refreshers, may cause corrosion of the domestic water lines,
resulting in a catastrophic failure of the Aqua-Hot system by
creating leaks that cannot be repaired. This damage is not
covered by the Aqua-Hot warranty.
If disinfecting the hot water heating system, be sure to follow
NFPA 1192 Standard on Recreational Vehicles “Instructions for
Disinfection of Potable Water Systems.”
Not winterizing the Aqua-Hot when freezing temperatures
are present will result in serious damage to the Aqua-Hot
domestic water heating system. Ensure that FDA approved
“GRAS” antifreeze rated for winterization is used when
winterizing this unit.
To Hot Water Outlets
Tempered
Domestic Hot Water
Fresh Water
Storage Tank
Cold Water Faucets
Demand Pump
Tempering
Valve
Figure 18
General Troubleshooting
Should the Aqua-Hot Hydronic Heating System fail to operate,
complete the following checks:
1. Verify that the Aqua-Hot is supplied with electrical power.
2. Make sure there is an adequate supply of diesel fuel (at
least ¼ tank).
3. Ensure that the Aqua-Hot boiler tank has an adequate
supply of antifreeze and water heating solution by
checking the level at the expansion tank. If the level is low,
reference the maintenance section of this guide for relling
instructions.
4. Verify the functionality of any in-line fuses connected to the
Aqua-Hot. Replace these fuses if necessary.
5. Ensure that all coach-side hot water faucets are closed.
6. Visually inspect the interior of the Aqua-Hot to ensure that
there are not any pinched or damaged wires.
7. Locate the high-limit thermostats (3) within the Aqua-Hot.
Test these thermostats for functionality, and replace if
necessary.
8. Locate and test the ETS module for functionality. Replace
if necessary.
9. Locate and test the uid circulation pump. Replace if
necessary.
10. Locate the three-way valve and test it for functionality.
Replace if necessary.
11. Make sure there are no faults displayed on the LCD screen
as shown below.
NOTE: The uid level sensor is located in the Aqua-Hot’s
expansion tank. If the antifreeze solution in the expansion
tank drops below the level of the uid sensor, the Aqua-Hot
will not operate.
Hot Fluid Line
Cold Fluid Line
Fluid Level Sensor
Fill Cap
Lower Fitting
Upper Fitting
Figure 20
General Troubleshooting
Figure 19
Fluid Fill Port
Figure 21
Expansion Bottle
Connection

Service LogAppendix
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622 ©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 17p. 16
DATE SERVICE PERFORMED SERVICE CENTER
Properly Apply Antifreeze to the Prism Assembly
Use the guide below to properly apply the ethylene glycol
mixture to the prism assembly of the refractometer. Once that
is complete, peer through the eyeglass of the refractometer to
continue to the next step.
Adjust the Boundary Line
Once the glycol solution has been properly applied, adjust the
calibration screw until the boundary line labeled “Ethylene
Glycol” is set to 32°F. The graphic to the right has been designed
as an aid, but note that it may differ from what is shown in the
refractometer sight glass.
Application of Ethylene Glycol
Poor Poor Good
Application of Propylene Glycol
Boundary Line
Adjust to 32°F
Lower White Field
Upper Blue Field
Refractometer Sight Glass
Measuring Antifreeze Using a Refractometer
Eye Piece
Prism Assembly
Daylight Plate
Assembly
Calibration Screw

2-YEAR LIMITED WARRANTY AQUA-HOT®
HYDRONIC HEATING SYSTEM
Aqua-Hot Heating Systems Inc. warrants the Aqua-Hot Heater to be free from defects in
material and workmanship under normal use and service for a period of two years on
both parts and labor commencing upon the original date of registration of the vehicle.
Replacement parts are warranted for the remainder of the Heater’s standard warranty
coverage or for six months, whichever is greater. The intent of this warranty is to protect
the heater’s end-user from such defects, which would occur in the manufacturing of the
product. Thus, problems due to improper specications, improper installations, improper
use, the use of accessory parts or parts not authorized by Aqua-Hot Heating Systems Inc.,
repair by unauthorized persons, and damage or abuse of the heater are specially excluded
from warranty coverage.
For additional information, or to obtain a warranty repair authorization, please contact the
Aqua-Hot Heating Systems Warranty Administrator at 574-AIR-XCEL (574-247-9235) (7:00
AM to 4:00 PM Mountain Standard Time) or visit www.aquahot.com.
My Comfort Zones are On-Board
Vehicle:
Purchased From:
Dealer Information:
Name:
Location:
Phone Number:
Heating System:
Serial Number:
Warranty
Warranty Registration
Register your warranty with one of the following steps:
1. Scan the code to the right with your smartphone.
2. Visit the following link:
https://www.aquahot.com/Service-Help/Warranty-Registration.aspx
Service Log
©Aqua-Hot® 125-DN1 Use and Care Guide REV 220622
p. 18
DATE SERVICE PERFORMED SERVICE CENTER

Aqua-Hot Heating Systems, LLC
7501 Miller Drive, Frederick, CO 80504
Visit us online at www.aquahot.com
Call us at 574-AIR-XCEL (574-247-9235)
©2022 Aqua-Hot Heating Systems, LLC. Printed in the USA
LTE-125-001
100SERIES
Warranty Registration
Register your warranty with one of the following steps:
1. Scan the code to the right with your smartphone.
2. Visit the following link:
https://www.aquahot.com/Service-Help/Warranty-Registration.aspx