Aqua-hot 675-d User manual

Ow n e r ’sMa n u a l

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

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�

— Page 1 —

INTRODUCTION

3069328 Direct Vent Appliance

Figure 1

— Page 2 —

Figure 2

INTRODUCTION

— 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

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�

— 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

— 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.

— 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�

— 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

WINTERIZATION

Not winterizing the Aqua-Hot when freezing temperatures

are present will result in serious damage to the Aqua-Hot’s

domestic water heating system. Also, be sure to use an

FDA approved, “GRAS” rated antifreeze for winterization.

NOTE: The Aqua-Hot can continue to be used for interior

zone heating once the domestic water heating system

has been drained and winterized�

The Aqua-Hot’s domestic water heating system must be com-

pletely drained of domestic water any time the heater is stored

where freezing temperatures may be experienced�

Winterizing the Domestic Water Heating System:

Please follow these instructions when winterizing the Aqua-

Hot’s domestic water heating system� Reference Figure 10:

1. Completely drain the fresh water storage tank�

2. Disconnect the domestic water demand pump’s 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 FDA-approved “GRAS” RV Antifreeze�

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 the hot and cold faucets�

6. Remove the hose and reconnect the domestic water demand

pump’s suction line to the fresh water storage tank�

De-Winterizing the Domestic Water Heating System:

For de-winterization, completely ll the fresh water storage tank.

Open and close all interior and exterior water faucets, one at a

time, until only clear water is present/visible� Reference Figure 10

If disinfecting the potable water system after de-winterizing,

be sure to follow RVIA’s “Instructions for Disinfection of

Potable Water Systems on Recreation Vehicles�” These in-

structions can be obtained by contacting the Recreational Vehicle

Industry Association at (703) 620-6003, visiting them online at

www.rvia.com, or writing to them at the following address:

Recreation Vehicle Industry Association

1896 Preston White Drive

P.O. Box 2999

Reston, VA 20195-0999

— Page 8 —

RV

Antifreeze

Arrows indicate directional flow of

domestic water.

To Hot Water Faucets

Domestic

Hot Water

OUTLET

Fresh

Water Storage

Tank

Domestic

Cold Water

INLET

To Cold Water

Faucets

Demand

Pump

Figure 10

TROUBLESHOOTING

General Information

Should the Aqua-Hot Hydronic Heating System fail to operate,

complete the following checks:

1) Verify that the Aqua-Hot’s access cover is securely installed�

The Aqua-Hot system will not operate if the access cover is

not fully installed�

3) Ensure that the vehicle’s fuel tank contains a sufcient level

of fuel� The Aqua-Hot system will not operate if the diesel

fuel level is at or below 1/4 tank�

4) Ensure that the Aqua-Hot’s 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, refer-

ence the “Maintenance” section of this manual for relling

instructions�

5) If the Aqua-Hot’s diesel-burner switch “Indicator Light”

does not illuminate, and the diesel-burner is not function-

ing, locate the electronic controller and check the following:

a) Check the Aqua-Hot’s electronic controller for any

RED lights indicating a fault condition� Reference

Figure 11�

b) Check for loose wire connections on the electronic

controller’s terminal strips/plugs� When checking for

loose terminal strips/plugs, remove the electronic con-

troller faceplate by unscrewing the four cover screws�

c) Remove the Aqua-Hot’s access cover and check for

loose plug connectors on the diesel-burner controller�

Reference Figure 4�

If the Aqua-Hot system’s failure to operate is not resolved with

the above checks, please contact Aqua-Hot Technical Support

Department at 1-800-685-4298 for additional assistance or visit

the web site at www.aqua-hot.com�

— Page 9 —

Electronic Controller Diagnostic

Low Tank-Level Cutoff Indicator Light:

This indicator light will illuminate RED when either the electric

heating elements and/or diesel-burner have automatically shut

down due to a low antifreeze and water heating solution level

inside the Aqua-Hot’s boiler tank� This fault will automatically

reset when the low level condition is corrected�

Low Battery Voltage Fault Indicator Light:

This indicator light will illuminate RED and the diesel-burner

will shut down whenever the 12 Volt-DC voltage level is too

low for the Aqua-Hot to operate properly� This fault must

be manually reset after the voltage level has been restored to

the 12 Volt-DC battery system� Reference the Low Voltage

information below�

Low Voltage Fault Indicator Light and Reset Button:

The Aqua-Hot’s electronic controller must be manually reset

whenever the low battery voltage fault indicator light has been

activated� The electronic controller can be reset by turning

OFF the diesel-burner switch on the interior switch panel for

Figure 11

TROUBLESHOOTING

approximately 30 seconds, then turning the switch back ON

or by pressing the “Low Voltage Reset” button located on the

electronic controller (use a thin, straight, nonmetallic object to

access the reset button through the small hole in the faceplate)�

Overload Fault Indicator Light:

This indicator light will illuminate RED whenever one of the

following conditions have occurred:

1) The Aqua-Hot is off due to an electrical overload (i�e�,

short) in the main 12 Volt-DC power supply circuitry�

2) The Aqua-Hot is off due to a combination of high

electrical 12 Volt-DC power loads and a high surface

temperature of the electronic controller�

The Aqua-Hot will automatically restart once the electrical

overload (i�e�, short) and/or high-heat condition is corrected�

Heating Zones Status Indicator Lights:

These ve indicator lights (separately) will illuminate GREEN

whenever a zone thermostat, for each particular zone, is calling

for heat� The GREEN indicator lights also indicate that 12

Volt-DC power is being supplied to the particular interior

heating zone’s heat exchangers (i�e�, fan motors)� If any of the

ve indicator lights illuminate RED, it indicates that an electrical

overload condition (i�e�, short) has occurred in a particular

heating zone’s circuitry�

NOTE: The low temp cutoff light must be illuminated and

heater must be up to operating temperature�

A short in either a heating zone’s interior room

thermostat or a heating zone’s heat exchanger circuit

will cause the indicator light to illuminate RED�

Pumps #1, #2, and #3 Indicator Lights:

These indicator lights (separately) will illuminate GREEN

whenever a circulation pump is operating� If any of the three

indicator lights illuminate RED, it indicates that an electrical

overload condition (i�e�, short) has occurred in the particular

component’s circuitry�

NOTE: Zone circulation pumps #1 and #2 are activated

whenever a zone thermostat calls for heat� The

#3 boiler tank stir pump is activated whenever the

domestic water is being used on a continuous basis or

the heater is not up to operating temperature�

— Page 10 —

Engine Preheat Pump Indicator Light:

This indicator light will illuminate GREEN whenever the

engine preheat circulation pump is operating� Please note that

this light will only be active if the engine preheat switch is

ON in conjunction with either the diesel-burner and/or the

electric element switch� If this indicator light illuminates RED,

it indicates an electrical overload condition (i�e�, short) has

occurred in this particular component’s circuitry�

NOTE: The Aqua-Hot must be up to operating temperature

and the Low Temp Cutoff Light must be illuminated�

Heating Status Indicator Light:

This indicator light will illuminate GREEN whenever the Aqua-

Hot’s VDC/VAC control thermostat is calling for heat, allowing

the antifreeze and water heating solution in the Aqua-Hot’s

boiler tank to be heated by either the diesel-burner and/or the

electric heating element� When this indicator light is off, no heat

is being supplied to the Aqua-Hot’s boiler tank by either of these

two heat sources�

NOTE: The Aqua-Hot’s VDC/VAC control thermostat will

automatically activate the diesel-burner and/or the

electric heating element only if the diesel-burner and/

or electric element switch is in the ON position�

Electric Heating Element Status Indicator Light:

This indicator light will illuminate GREEN whenever the Aqua-

Hot’s electric heating element is operating and providing heat to

the Aqua-Hot’s boiler tank� Please note that this light will only

be active if the electric element switch is in the ON position�

If this indicator light illuminates RED, it indicates an electrical

overload condition (i�e�, short) has occurred in the electric

heating element’s 12 Volt-DC powered circuitry�

Appendix A

Antifreeze Types

APPENDIX A: ANTIFREEZE TYPES

The following information addresses the neces-

sary usage of a propylene glycol based “boiler” type

antifreeze in the Aqua-Hot� Propylene glycol is a safer

alternative to the more toxic ethylene glycol antifreeze;

however, as mandated by IAPMO (International As-

sociation of Plumbing and Mechanical Ofcials), only

those propylene glycol based “boiler” type antifreezes

deemed “Generally Recognized as Safe” (GRAS) by the

FDA should be utilized�

Because of the signicant impact various types of anti-

freeze can have on a hydronic heating system, including

the level of safety provided, it has been recognized that

there is a need to provide an explanation regarding two

additional prominent types of antifreeze/coolant avail-

able� The following information should be utilized as

an educational means of ensuring that the proper type

of propylene glycol based antifreeze is selected:

RV & Marine Antifreeze:

These types of propylene glycol based antifreeze

products are formulated specically for “winterizing”

applications only� Although RV & Marine antifreeze

is often “Generally Recognized as Safe” by the FDA,

it should never be used in the Aqua-Hot’s Hydronic

Heating System� This type of antifreeze is not formu-

lated to transfer heat, which is essential to the Aqua-

Hot’s functionality and does not contain rust inhibitors�

Please note, however, that RV & Marine antifreeze can

be utilized to winterize the Aqua-Hot’s Domestic Water

Heating System�

Automotive Antifreeze/Coolant:

These types of propylene glycol based antifreeze prod-

ucts are formulated specically to protect automotive

engines against corrosion, freezing temperatures, and

overheating� They also have excellent heat transfer and

thermal conductivity characteristics� Although these

types of antifreeze products are considered less toxic

and safer than ethylene glycol for people, pets, and the

environment, they are not “Generally Recognized as

Safe” (GRAS) rated by the FDA� Therefore, they must

be marked with a “harmful if swallowed” warning�

This additional warning is required because these types

of antifreeze products contain high levels of chemi-

cal rust inhibitors� Due to their potentially hazardous

properties, they should never be used in the Aqua-

Hot’s Hydronic Heating System�

— Page A-1 —

Appendix B

Antifreeze Mixture Water

Quality Recommendations

APPENDIX B: ANTIFREEZE MIXTURE WATER QUALITY RECOMMENDATIONS

In order to ensure maximum performance and longev-

ity of an Aqua-Hot Heating System’s boiler tank and

associated components, it has been determined that

there is a need to use distilled, de-ionized, or soft water

in combination with concentrated propylene glycol for

the Aqua-Hot’s antifreeze and water heating solution�

Please note that this is only necessary when mixing

concentrated propylene glycol antifreeze with water;

suppliers of pre-mixed antifreeze are responsible for

the use of high-quality (distilled, de-ionized, or soft)

water when preparing their antifreeze for sale�

Hard water possesses a high-level of calcium and

magnesium ions, which deplete the propylene glycol

antifreeze’s corrosion inhibitors� This, in turn, causes

the antifreeze and water heating solution to begin turn-

ing acidic, which can corrode the Aqua-Hot’s boiler

tank and associated components prematurely� There-

fore, concentrated propylene glycol should be diluted

with distilled, de-ionized, or soft water which is 80 ppm

or less in total hardness� The local water agency should

have up-to-date water quality reports which should

indicate if the local tap water is within this guideline�

— Page B-1 —

Appendix C

Antifreeze Terms

and Mixture Ratio

APPENDIX C: ANTIFREEZE TERMS AND MIXTURE RATIO

The following information addresses the process of

selecting an antifreeze and water mixture ratio that pro-

vides adequate freeze, boiling, and rust/anti-corrosive

protection� A 50/50 mixture ratio is recommended,

which will result in a freeze point of approximately

-28ºF and a boil point of approximately 222ºF�

The following information should be utilized for the

purpose of clarifying some terms commonly associated

with antifreeze�

Freeze Point and Burst Point:

Antifreeze lowers the freezing point of any liquid, to

which it has been added, by preventing the formation

of ice crystals; however, as the ambient temperature

continues to decline, the water in the solution will at-

tempt to attain a solid state� The point in which the

water begins to solidify is termed the “Freeze Point�”

Although the water in the solution has begun to freeze,

producing a “slushy” consistency, the antifreeze in the

solution will continue to combat the normal expansion

of the solution as it freezes� The point in which the so-

lution can begin to expand, due to colder temperatures,

is called the “Burst Point�” Once the solution reaches

the burst point, the potential is present for ruptured

pipes to exist� The burst point of the antifreeze and

water heating solution is dependent upon the brand of

propylene glycol employed�

Boiling Point:

The Aqua-Hot utilizes the antifreeze and water heat-

ing solution as a transportation means for the heat

produced from the internal processes� The antifreeze

absorbs the heat created until its boiling point is

reached; it is at this point that the liquid turns to a gas

and is expelled to prevent the heating system from

overheating� Each time the boiling point is reached,

a loss of efciency occurs because the heat produced

is expelled rather than utilized for the function of the

heating system� Therefore, a higher boiling point is

desired in order to combat the loss of efciency, which

allows the antifreeze to transport the heat created from

the internal process throughout the motorhome where

it can be utilized productively rather than dissipating

due to its change from a liquid to a gas�

— Page C-1 —

APPENDIX C: ANTIFREEZE TERMS AND MIXTURE RATIO

Rust and Anti-Corrosive Inhibitors:

Another major function of antifreeze is to provide

protection to the internal metal components of the

Aqua-Hot Hydronic Heating System from corrosion

and rust� Antifreeze is able to perform this function

by the addition of rust- and anti-corrosive inhibitors,

which are designed specically to activate in a water

solution�

Summary:

Antifreeze has three basic functions: freeze protec-

tion, boil-over protection, and anti-corrosion and rust

protection�

Antifreeze is also primarily responsible for heat trans-

fer; however, antifreeze itself does not possess accept-

able heat transfer characteristics� Therefore, as water is

an excellent heat conductor, it is added to the mixture�

A 50/50 solution of propylene glycol antifreeze and

water is recommended to provide the best perfor-

mance combination of the aforementioned functions�

If excess propylene glycol exists within an antifreeze

and water heating solution, the water’s heat absorption

properties are compromised, which could ultimately in-

hibit the Aqua-Hot from providing adequate domestic

hot water and interior heating�

Additionally, if the antifreeze and water heating solu-

tion contains over 70 percent antifreeze, the freezing

point is actually raised, resulting in less freeze protec-

tion� Please reference the attached graphical represen-

tation regarding the percentage of antifreeze to water

and how it directly affects the solution’s freezing point�

— Page C-2 —

Aqua-Hot 675-D User manual

Popular Heater manuals by other brands