Aqua-Hot 675-D User manual

Ow n e r ’sMa n u a l
© 2008 Aqua-Hot Heating Systems Inc.

TABLE OF CONTENTS
Limited Warranty Statement
Introduction
Introduction to the Aqua-Hot Hydronic Heating System������������������������������������������������������������������������������Page 1
Operating Instructions
Activating the Aqua-Hot Hydronic Heating System���������������������������������������������������������������������������������������Page 6
Zone Thermostat Operation�������������������������������������������������������������������������������������������������������������������������������Page 7
Using the Domestic Water Heating System������������������������������������������������������������������������������������������������������Page 8
Aqua-Hot Operational Flow-Chart��������������������������������������������������������������������������������������������������������������������Page 9
Maintenance
Monthly Maintenance�����������������������������������������������������������������������������������������������������������������������������������������Page 11
Replenishing the Antifreeze and Water Heating Solution ����������������������������������������������������������������������������Page 11
Annual Maintenance�������������������������������������������������������������������������������������������������������������������������������������������Page 12
Winterization
Winterizing the Domestic Water Heating System������������������������������������������������������������������������������������������Page 13
De-Winterizing the Domestic Water Heating System�����������������������������������������������������������������������������������Page 13
Troubleshooting
General Information�������������������������������������������������������������������������������������������������������������������������������������������Page 15
Electronic Controller Diagnostic����������������������������������������������������������������������������������������������������������������������Page 16
Appendices
Appendix A: Antifreeze Types��������������������������������������������������������������������������������������������������������������������������������A-1
Appendix B: Antifreeze Mixture Water Quality Recommendations����������������������������������������������������������������� B-1
Appendix C: Antifreeze Terms and Mixture Ratio���������������������������������������������������������������������������������������������� C-1
© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual

2-YEAR LIMITED WARRANTY
AQUA-HOT® HYDRONIC HEATING SYSTEM
AHE-675-D
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 specically excluded from warranty coverage.
For additional information or to obtain a warranty repair authorization, please contact the Aqua-Hot Heating
Systems Warranty Administrator at 1-800-685-4298 (8:00 AM to 5:00 PM Mountain Standard Time) or visit
www�aqua-hot�com�

INTRODUCTION
This manual should be maintained in legible condition and
kept in a safe, easily accessible place for future reference.
Please read the complete owner’s manual prior to operating
the Aqua-Hot Hydronic Heating System. Be sure to ll
out and mail in the “Warranty Registration” card at the
front of this manual.
The Aqua-Hot Heating System is a Hydronic Heating System
that provides interior zone heating where and when it is needed,
as well as a continuous, on-demand supply of domestic hot
water� Both heating features are accomplished by a 12 Volt-DC
powered diesel-burner and one 2000 Watt, 120 VAC electric
heating element and one 4500 Watt, 240 VAC electric heating
element�
The Aqua-Hot 675-D also includes an engine preheat feature�
This preheat feature provides an easy engine start-up whenever
cool weather conditions are present�
These heating sources are used in conjunction with an FDA-
approved “GRAS” (Generally Recognized As Safe) propylene
glycol based antifreeze and water heating solution in order to
provide a continuous supply of domestic hot water, interior/
fresh water tank heating, independent interior zone heating, and
engine preheating� Be sure to reference Figures 1 through 4 for
a complete component overview�
NOTE: This Aqua-Hot product utilizes a propylene glycol
based antifreeze and water heating solution� Propylene
glycol based solution is a boiler type antifreeze that is
“Generally Recognized as Safe” (GRAS) by the FDA�
For additional information regarding this “GRAS”
antifreeze product, please reference the Appendices,
contact the Aqua-Hot Heating Systems Technical
Support Department at 1-800-685-4298, or visit the
Web site at www.aqua-hot.com�
Danger, Warning, Caution, and Note Boxes:
Danger, Warning, Caution, and Note boxes appear throughout this
manual as a means of alerting the operator to important information�
In d I c a t e s t h a t p e r s o n a l I n j u r y I s l I k e l y o r I m m I n e n t .
Indicates that serious damage to the heater will occur and
personal injury is possible as well.
Indicates that damage to the heater is possible�
NOTE: Indicates information that requires special attention by
the operator�
© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual
— Page 1 —

INTRODUCTION
3069328 Direct Vent Appliance
Figure 1
© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual
— Page 2 —
Figure 2

INTRODUCTION
© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual
— Page 3 —
Figure 3
Product I.D.
Label
Heating Zone 3
Outlet Port
AC Wiring Ports
Wire Harness
& Port
Air Release
Valve
Top of 675-D
Heating
Zone
Return
Ports
Heating Zone 2
Outlet Port
Heating Zone 1
Outlet Port
Diesel Fuel
Inlet /Outlet
Ports
Engine
Preheat
Inlet /Outlet
Ports
Domestic Water
Inlet /Outlet
Ports
Expansion Tank
Connection
Figure 4
Zone 1
Circulation
Pump
Zone 3
Circulation
Pump
Zone 2
Circulation
Pump
Engine
Preheat
Circulation
Pump
Diesel-Burner
Diesel-Burner
Controller
Interlock Switch
Domestic
Water Access
Panel
Drain Valve
Air Release Valve

OPERATING INSTRUCTIONS
The Aqua-Hot’s exhaust is HOT!
DO NOT park in areas where dry conditions exist under-
neath the vehicle, (e.g., in a dry, grassy eld) as a re may
result!
DO NOT operate the Aqua-Hot’s diesel-burner inside an
enclosed building!
The heater must be switched OFF when refueling.
DO NOT operate the diesel-burner and/or electric heating
element without the antifreeze and water heating solution in the
Aqua-Hot’s boiler tank� Failure to do so will cause serious dam-
age to the heater�
Activating the Aqua-Hot Hydronic Heating System:
Diesel-Burner:
Turn the diesel-burner switch ON. Reference Figure 5� This
procedure will activate the diesel-burner and the indicator light
located on the diesel-burner switch� Allow 10-20 minutes for
the Aqua-Hot to reach operating temperature�
Please note that the diesel-burner is the primary heat source
for heating both the interior and the domestic hot water (such
as when cool ambient temperatures exist and/or when there is a
high demand for domestic hot water)�
Electric Heating Element:
NOTE: The motorhome must be connected to shore power, or
the generator must be running, in order to activate the
electric heating element�
Low:
Turn the Electric Element switch ON in conjunction with the
High/Low switch placed in the LOW position; reference Figure
3� This procedure will activate the 2000 Watt/120 VAC Electric
Heating Element and the indicator lights located on both the
Electric Element and High/Low switches� Allow 1-2 hours for
the Aqua-Hot System to reach operating temperature�
High:
Turn the Electric Element switch ON in conjunction with
the High/Low switch placed in the HIGH position; reference
Figure 5� This procedure will activate both of the electric heating
elements and the indicator lights located on both the electric
element and High/Low switches�
© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual
— Page 4 —
Allow 0�5-1 hour for the Aqua-Hot to reach operating
temperature� The electric heating elements are a secondary
heat source for heating both the interior and the domestic
hot water during low heating demand situations (such as when
moderate ambient temperatures exist and/or when there is a low
demand for domestic hot water)�
NOTE: Both the diesel-burner and the electric heating ele-
ments are thermostatically controlled� Either, or both,
heating sources will automatically maintain the temper-
ature of the Aqua-Hot’s antifreeze and water heating
solution between approximately 160°F and 190°F (±5)�
Therefore, to heat the motorhome/domestic hot water,
simply choose the desired heat source(s) and leave the
switch(es) (i�e�, diesel-burner and/or electric element)
ON�
Zone Thermostat Operation
Interior Room Thermostat:
Simply adjust each interior room thermostat to the desired
temperature� Then, whenever an interior room thermostat “calls
for heat,” the Aqua-Hot’s circulation pump and interior heat
exchanger fans will be activated� These devices, together, will
supply warmth and comfort to each interior heating zone� The
Aqua-Hot must be at operating temperature in order for the
zones to function. Please contact the specic motorhome man-
ufacturer for the exact location of the interior room thermostats�
Fresh Water Tank Thermostat:
Simply adjust the thermostat for bay heating to a minimum of
40°F� This will prevent freezing of the domestic water storage
system. Please contact the specic motorhome manufacturer for
the exact location of the fresh water tank thermostat�
Figure 5
Indicator
Light

© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual
— Page 5 —
OPERATING INSTRUCTIONS
Allow 0�5-1 hour for the Aqua-Hot to reach operating
temperature� The electric heating elements are a secondary
heat source for heating both the interior and the domestic
hot water during low heating demand situations (such as when
moderate ambient temperatures exist and/or when there is a low
demand for domestic hot water)�
NOTE: Both the diesel-burner and the electric heating ele-
ments are thermostatically controlled� Either, or both,
heating sources will automatically maintain the temper-
ature of the Aqua-Hot’s antifreeze and water heating
solution between approximately 160°F and 190°F (±5)�
Therefore, to heat the motorhome/domestic hot water,
simply choose the desired heat source(s) and leave the
switch(es) (i�e�, diesel-burner and/or electric element)
ON�
Zone Thermostat Operation
Interior Room Thermostat:
Simply adjust each interior room thermostat to the desired
temperature� Then, whenever an interior room thermostat “calls
for heat,” the Aqua-Hot’s circulation pump and interior heat
exchanger fans will be activated� These devices, together, will
supply warmth and comfort to each interior heating zone� The
Aqua-Hot must be at operating temperature in order for the
zones to function. Please contact the specic motorhome man-
ufacturer for the exact location of the interior room thermostats�
Fresh Water Tank Thermostat:
Simply adjust the thermostat for bay heating to a minimum of
40°F� This will prevent freezing of the domestic water storage
system. Please contact the specic motorhome manufacturer for
the exact location of the fresh water tank thermostat�
Figure 5
Indicator
Light
Using the Domestic Water Heating System
When the Aqua-Hot is at operating temperature, the domestic
water is automatically heated as it is being used� Because the
Aqua-Hot does not store any hot water, simply open any hot
water faucet, and a continuous supply of domestic hot water will
be present within a few seconds� This hot water feature is con-
tinuous and is accomplished by the Aqua-Hot’s domestic water
heating system� The diesel-burner switch on the interior switch
panel must be ON in order to obtain a continuous supply of hot
water (e�g�, during showers); be sure to also activate the electric
element switch, and place the “high/low” switch on HIGH for
maximum hot water capacity� Reference Figure 6�
Figure 6
Diesel-Burner switch
must be ON to obtain
a continuous supply of
hot water.
Activate the electric element
switch and place the high/low
switch on HIGH for maximum
hot water capacity.

OPERATING INSTRUCTIONS
Aqua-Hot Operational Flow-Chart
Heating Zone Thermostat
calls for heat.
The heated antifreeze and water heating
solution flows through the Hydronic Heating
System transferring heat to the heat
exchanger, which is, in turn, transferred to
the surrounding zone.
The cooled antifreeze and water heating
solution is returned to the Boiler Tank to be
reheated.
“Engine Preheat” switch on the Interior
Switch Panel is activated. (450-DE ONLY)
The engine’s coolant is circulated through
the Aqua-Hot’s internal Engine Preheat
System, where the heat from the Boiler
Tank is transferred to the engine’s coolant.
The antifreeze and water heating solution
within the Boiler Tank is reheated, as
needed, and continues warming the
engine’s coolant as it circulates through the
Aqua-Hot’s internal Engine Preheat
System.
A hot water faucet (e.g., kitchen sink,
shower, etc.) is opened.
Continuous hot water is supplied to the
faucet.
© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual
— Page 6 —

MAINTENANCE
Wh e n t h e aq u a -ho t I s a t m a x I m u m o p e r a t I n g t e m p e r a -
t u r e , t h e c o o l a n t W I l l b e v e r y hot! Ift h e aq u a -ho t ’s
h e a t I n g s y s t e m I s a c c e s s e d , s c a l d I n g b y h o t v a p o r o r c o o l -
a n t c o u l d r e s u l t !
be f o r e c l e a n I n g o r s e r v I c I n g , d I s c o n n e c t a l l p o W e r s u p -
p l I e s !
DO NOT operate the diesel-burner and/or the electric
heating element without the antifreeze and water heating
solution in the Aqua-Hot’s boiler tank; doing so will cause
serious damage to the heater.
Propylene Glycol that is “Generally Recognized As Safe”
by the FDA must be utilized for the antifreeze and water
heating solution.
NOTE: For additional information regarding this propylene
glycol-based, boiler-type antifreeze that has been
“Generally Recognized As Safe” by the FDA, please
reference the Appendices, contact the Aqua-Hot
Heating Systems Technical Support Department at
1-800-685-4298, or visit the Web site at
www.aqua-hot.com�
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 expan-
sion tank� Reference Figure 7� Please note that the coolant level
should be checked only when the Aqua-Hot is at maximum
operating temperature (i�e�, immediately after the diesel-burner
cycles OFF)� When the Aqua-Hot is at maximum operating
temperature, the antifreeze and water heating solution should be
at the level marked “HOT” on the expansion tank�
Replenishing the Antifreeze and Water Heating Solution:
If the antifreeze and water heating solution needs replenishing,
remove the expansion tank’s cap and ll the expansion tank to
the “HOT” level mark. When relling, open the air release valve
located on the expansion tank connection to release air pockets�
Reference Figure 8� Hold the valve open until all air is released�
If necessary, rell the expansion tank again to the level marked
“HOT.” Be sure the valve is closed when nished by hand-
tightening� Reference Appendices A through C to determine the
correct ratio of antifreeze to water, the proper type of anti-
freeze, and the water quality recommendations for the Aqua-Hot
system’s antifreeze and water heating solution�
© 2008 Aqua-Hot® 675-D Hydronic Heating System Owner’s Manual
— Page 7 —
Annual Maintenance:
To keep the Aqua-Hot running smoothly, it is ideal to have the
diesel-burner tuned-up annually� A tune-up should consist of a
new fuel nozzle and fuel lter. Reference Figure 9. To ensure
maximum diesel-burner performance, always use the recom-
mended fuel nozzle and fuel lter when replacing these parts.
Reference the Aqua-Hot’s service and parts manual for spare
parts information and detailed replacement instructions� Contact
the Aqua-Hot Technical Support Department at 1-800-685-4298
for assistance or to locate the nearest Aqua-Hot Service Center,
or visit the Web site at www.aqua-hot.com.
Figure 7
Air Release
Valve
Figure 8
Expansion Tank
Connection
Figure 9
Fuel Nozzle
Fuel Filter