AO Smith Water Heater 705 Series 100 User Manual

On-Demand Water Heater  
System Design Manual  
Design information for single and multiple unit  
installations for residential, commercial, recircula-  
tion and storage tank systems.  
PRINTED 0209  
186965-001  
Table of Contents  
Certifications..................................................................................3  
Installing Gas Water Heater...........................................................4-7  
Water Quality and Scale................................................................8  
Pump Sizing for Circulation..........................................................9  
Tank Water Heaters in a Circulation Loop  
...................................10  
Additional Guidelines  
....................................................................10  
Pump Sizing for Storage Tank Applications  
...............................11  
Pressure Loss Curves  
..................................................................12-13  
Domestic Hot Water - Standard Installation  
1 Water Heater  
(H-1).......................................................................14  
2 Water Heaters (H-  
3 Water Heaters (H-  
4 Water Heaters (H-  
5 Water Heaters (H-  
6 Water Heaters (H-  
2).....................................................................15  
3).....................................................................16  
4).....................................................................17  
5).....................................................................18  
6).....................................................................19  
Domestic Hot Water with Optional Freeze Protection  
on Outdoor Models  
1 Water Heater  
2 Water Heater  
3 Water Heaters (H-3-  
6 Water Heaters (H-6-  
(H-1-E)...................................................................20  
s (H-2-  
E) .................................................................21  
E) .................................................................22  
E) .................................................................23  
Domestic Hot Water with Circulation Systems  
1 Water Heater - Preferred (H-  
1-RP)...............................................24  
1 Water Heater - Optional (H-1-RO)  
................................................25  
2 Water Heaters - Preferred (H-2-RP)  
............................................26  
2 Water Heaters - Optional (H-  
2-RO)..............................................27  
3 Water Heaters - Preferred (H-3-RP)  
6 Water Heaters - Preferred (H-6-RP)  
............................................28  
.............................................29  
Domestic Hot Water with Backup Storage Tanks  
1 Water Heater  
(H-1-T) ...................................................................30  
1 Water Heater with Circulation (H-  
1-TC) ........................................31  
2 Water Heaters (H-2-  
T) ..................................................................32  
2 Water Heaters with Circulation (H-  
2-TC)......................................33  
3 Water Heaters (H-3-  
T) .................................................................34  
3 Water Heaters with Circulation (H-  
3-TC) .....................................35  
6 Water Heaters (H-6-  
T) .................................................................36  
6 Water Heaters with Circulation (H-  
6-TC) .....................................37  
Maintenance Procedure  
Scale Flush Procedure (MP-01)  
.......................................................38  
2
Approvals  
ATI-305-N  
ATI-305-P  
ATO-305-N  
ATO-305-P  
ATI-505-N  
ATI-505-P  
ATO-505-N  
ATO-505-P  
ATI-705-N  
ATI-705-P  
ATO-705-N  
ATO-705-P  
GTS-305-NI  
GTS-305-PI  
GTS-305-NE  
GTS-305-PE  
GTS-505-NI  
GTS-505-PI  
GTS-505-NE  
GTS-505-PE  
GTS-705-NI  
GTS-705-PI  
GTS-705-NE  
GTS-705-PE  
GT-305-NI  
GT-305-PI  
GT-305-NE  
GT-305-PE  
GT-505-NI  
GT-505-PI  
GT-505-NE  
GT-505-PE  
GT-705-NI  
GT-705-PI  
GT-705-NE  
GT-705-PE  
*AGT-705-NI  
*AGT-705-PI  
*AGT-705-NE  
*AGT-705-PE  
*ATI-705A-N *GTS-705-NIA  
*ATI-705A-P *GTS-705-PIA  
*ATO-705A-N *GTS-705-NEA  
*ATO-705A-P *GTS-705-PEA  
The models listed in this manual have received the following certifications except where noted:  
U
P
C
R
*
Water heaters are built in accordance with the requirements of the ASME Boiler  
and Pressure Vessel Code and received the Certificate of Authorization from the  
National Board. The heat exchanger has the NB and the HLW stamps.  
The California Safe Drinking Water and Toxic Enforcement Act requires the Governor of California to  
publish a list of substances known to the State of California to cause cancer, birth defects, or other  
repoductive harm, and requires businesses to warn of potential exposure to such substances.  
WARNING: This product contains a chemical known to the State of California to cause cancer, birth  
defects, or other reproductive harm.  
This appliance can cause low-level exposure to some of the substances included in the Act.  
3
Installation  
Consumer Information  
The on-demand water heaters must be installed according to all local and state codes or, in the absence  
of local and state codes, the “National Fuel Gas Code”, ANSI Z223.1 (NFPA 54) - current edition.  
CSA American, Inc.  
8501 East Pleasat Valley Road  
Cleveland, OH 44131  
National Fire Protection Association  
1 Batterymarch Park  
Quincy, MA 02269  
Check your phone listings for the local authorities having jurisdiction over your installation.  
Consumer Responsibilities  
This manual has been prepared to acquaint you (trained service technician) with the installation, oper-  
ation, and maintenance of the on-demand water heater and provide important safety information in these  
areas.  
Read all of the instructions thoroughly before attempting the installation or operation of the water heater.  
Service to the on-demand system should only be performed by a trained service technician.  
Massachusetts code requires this water heater to be installed in accordance with Massachusetts Plumbing  
and Fuel Gas Code 248 CMR Section 2.00 and 5.00.  
Water Temperature Regulation  
WARNING  
For systems with storage tanks, the water  
temperature in certain situation may vary up  
to 30°F (16.7°C) higher or lower at the point  
of use such as, bathtubs,showers, sink, etc.  
HOTTER WATER CAN SCALD: Water heat-  
ers, are intended to produce hot water. Water  
heated to a temperature which will satisfy  
space heating, clothes washing, dish wash-  
ing, and other sanitizing needs can scald and  
permanently injure you upon contact. Some  
people are more likely to be permanently in-  
jured by hot water than others. These include  
the elderly, children, the infirm, or physically/  
mentally handicapped. If anyone using hot  
water in the home fits into one of these  
groups or if there is a local code or state law  
requiring a certain temperature water at the  
hot water tap, then you must take special  
precautions.  
Water temperature over 125°F can cause  
severe burns instantly or death from scalds.  
Children, disabled and elderly are at highest  
risk of being scalded.  
Feel water before bathing or showering.  
Temperature limiting valves are available.  
4
Installation  
In addition to using the lowest possible temperature setting that satisfies your hot water needs, a means  
such as a mixing valve, should be used at hot water taps used by these people or at the water heater.  
Mixing valves are available at plumbing supply or hardware stores. Follow manufacturer’s instructions for  
installation of the valves. Before changing the factory setting on the thermostat see table below. Using  
the lowest hot water temperature that meets your needs will also provide the most energy efficient oper-  
ation of the water heater.  
Never allow small children to use a hot water  
Temperature  
Settings  
Time to Produce 2nd & 3rd  
Degree Burns on Adult Skin  
tap, or to draw their own bath water. Never  
leave a child or handicapped person un-  
attended in a bathtub or shower.  
160°F (71°C)  
150°F (66°C)  
140°F (60°C)  
130°F (54°C)  
120°F (49°C)  
80°F (27°C)  
About 1/2 second  
About 1-1/2 seconds  
Less than 5 seconds  
About 30 seconds  
NOTE: A water temperature range of 120°F -  
140°F (49°C-60°C) is recommended by most  
dishwasher manufacturers.  
More than 5 minutes  
- - - - - - - - - - - - - - - -  
Table “A”  
The thermostat of the water heater has been factory set at 120° F, to reduce the risk of scald injury. It is  
adjustable and can be reset to the desired temperature setting. Some states have a requirement for a  
lower setting. If you need hotter water, follow directions for temperature adjustment, but beware of the  
warnings in this section.  
Site Location  
Select a location near the center of the water piping system.  
Consider the exhaust vent system piping and combustion air supply requirements when selecting the  
water heater location. The venting system must be able to run from the water heater to the termina-  
tion with a minimal length and number of elbows.  
Locate the water heater near the existing gas piping. If installing a new gas line, locate the water  
heater to minimize the pipe length and elbows.  
NOTE: This water heater must be installed according to all  
local and state codes or, in the absence of local and state  
codes, the “National Fuel Gas Code”, ANSI Z223.1(NFPA  
54)-current edition.  
The water heater should be located in an area not subject to freezing temperatures. Water heaters  
located in unconditioned spaces (i.e., attics, basements, etc.) may require insulation of the water piping  
and drain piping to protect against freezing. The drain and controls must be easily accessible for oper-  
ation and service. Maintain proper clearances as specified on the data plate.  
5
For Storage Tank System Installation  
CAUTION - PROPERTY DAMAGE HAZARD  
The storage tank should be located in an area  
where leakage of the tank or connections will not  
result in damage to the area adjacent to the storage  
tank or to lower floors of the structure. Due to the  
normal corrosive action of the water, the tank will  
eventually leak after an extended period of time. Also  
any external plumbing leak, including those from  
improper installation, may cause early failure of the  
tank due to corrosion if not repaired. If the owner/  
operator is uncomfortable with making the repair a  
qualified technician should be contacted. A suitable  
metal drain pan should be installed under the storage  
tank as shown below, to help protect the property  
from damage which may occur from condensate form-  
ation or leaks in the piping connections or tank. The  
pan must limit the water level to a maximum depth of  
1-3/4” and be two inches wider than the tank and  
piped to an adequate drain. NOTE: The pan must  
not restrict combustion air flow. Locate the storage  
tank near a suitable indoor drain. Outside drains are  
subject to freezing temperatures which can obstruct  
the drain line. The piping should be at least 3/4” ID  
and pitched for proper drainage.  
Figure “1”  
Storage Tank  
A suitable metal drain pan  
should be installed under  
the storage tank.  
Pipe to an  
adequate drain  
1-3/4”  
max.  
At least 2” greater than  
the storage tank.  
Closed System/Thermal Expansion  
CAUTION - PROPERTY DAMAGE HAZARD  
Figure “2”  
Typical water  
In a closed system use a  
thermal expansion tank  
Hot Water  
Return Line  
Cold Water  
Inlet Valve  
piping installation  
Pressure Reducing  
Valve with Bypass  
As water is heated, it expands (thermal expan-  
sion). In a closed system, the volume of water  
will grow. As the volume of water grows, there  
will be a corresponding increase in water pres-  
sure due to thermal expansion. Thermal expan-  
sion can cause premature tank failure (leakage).  
This type of failure is not covered under the  
limited warranty. Thermal expansion can also  
cause intermittent temperature-pressure relief  
valve operation: water discharged from the valve  
due to excessive pressure build up. The temper-  
ature / pressure relief valve is not intended for  
the constant relief of thermal expansion. This  
condition is not covered under the limited war-  
ranty.  
Cold Water Supply  
to Fixture  
Hot Water  
Outlet  
Main Water  
Supply  
Temperature and  
Pressure Relief Valve  
Storage  
Tank  
Discharge line  
6” Max. above drain  
1“ Min.  
A properly-sized thermal expansion tank should  
be installed on all closed systems to control the  
harmful effects of thermal expansion. Contact a  
local plumbing service agency to have a thermal  
expansion tank installed.  
Drain line 3/4”  
ID Min.  
Massachusetts:  
Metal Drain  
Pan 1-3/4”  
Depth Max.  
Drain  
Install a vacuum relief  
in cold water line per  
section 19 MGL 142  
6
For Storage Tank System Installation  
Temperature and Pressure Relief Valve  
For protection against excessive pressures and temperatures, a temperature and pressure relief valve  
must be installed in the opening on the on-demand storage tank. This valve must be design certified by  
a nationally recognized testing laboratory that maintains periodic inspection of the production of listed  
equipment or materials as meeting the requirements for Releif Valves for Hot Water Supply Systems,  
ANSI Z21.22. The function of the temperature and pressure relief valve is to discharge water in large  
quantities in the event of excessive temperature or pressure developing in the water heater. The valve’s  
relief pressure must not exceed the working pressure of the water heater as stated on the data plate.  
IMPORTANT: Only a new temperature and pressure relief valve should be used with your water heater.  
Do not use an old or existing valve as it may be damaged or not adequate for the working pressure of  
the new water heater. Do not place any valve between the relief valve and the tank.  
WARNING  
Explosion Hazard  
If the temperature and pressure relief valve  
is dripping or leaking, have a qualified  
service technician replace it.  
Examples of a qualified service technician  
include: Licensed plumbers, authorized gas  
company personnel, and authorized service  
personnel.  
Do not plug valve.  
Do not remove valve.  
Failure to follow these instructions can  
result in death, or explosion.  
7
Water Quality and Scale  
A complete water analysis and an understanding of system requirements are needed to protect the  
on-demand water heaters and water heating systems from scale. Water analysis shows whether  
water is hard or soft. Hard water, unless treated, will cause scaling or liming of the heat exchanger.  
The rate of scaling increases with temperature and usage because calcium carbonate and other  
scaling compounds lose solubility (fallout of solution) at higher temperatures. For example, for every  
20°F over 140°F, the rate of scale increases by a factor of 2 (See figure below). Reference target  
water quality levels found in the operation / installation manual and consider water treatment if these  
levels are exceeded. *  
*
BASED ON 10 grains/gal HARDNESS  
210  
180°F  
180  
170°F  
150  
160°F  
120  
90  
150°F  
140°F  
60  
30  
120°F  
0
WATER USAGE, gal/day  
Figure “3”  
*Source 2003 ASHRAE Handbook HVAC Applications  
8
Pump Sizing for Circulation  
1. Use the chart below or one appropriate for your conditions to determine the heat loss in the length of  
the hot water supply and return piping. For example, 100 ft of 1-1/2 in bare copper tubing results in a  
heat loss of 5300 Btu/h.  
Approximate Heat Loss from Piping at 140 ºF Inlet, 70 ºF Ambient *  
Nominal Size, in.  
Bare Copper Tubing, 1/2 in. Glass Fiber Insulated  
Btu/h-ft  
Copper Tubing, Btu/h-ft  
3/4  
1
30  
17.7  
20.3  
23.4  
25.4  
29.6  
33.8  
39.5  
48.4  
38  
1-1/4  
1-1/2  
2
45  
53  
66  
2-1/2  
3
80  
94  
4
120  
* Source: 2003 ASHRAE Handbook HVAC Applications  
Table “B”  
2. Determine the acceptable temperature drop at the last fixture in the loop. For example, if the supply  
temperature from the water heater is 120 ºF (49 ºC) and an acceptable temperature at the last fixture  
is 100 ºF (38 ºC) then the acceptable temperature drop is 20 ºF (7 ºC).  
3. Calculate the required pump flow rate using the following formula:  
FLOW RATE (gpm) =  
HEAT LOSS (BTU / h)  
500 X ACCEPTABLE TEMPERATURE DROP (ºF )  
4. Based on the above calculations select a pump for the type of circulation system you will be utilizing:  
A). Preferred Method (reference drawing H-1-RP) - Reference pump manufacturers flow vs.  
pressure specifications to select a pump that can provide the flow rate calculated above  
while overcoming the pressure loss through:  
Tank water heater (reference manufacturer’s information)  
All building supply and return plumbing in the circulation loop (reference  
local plumbling codes, standards, or practices)  
B). Optional Method (H-1-RO) - Reference pump manufacturers flow vs. pressure specifications  
to select a pump that can provide 3 gpm of flow or the flow rate calculated above, whichever  
is greater, while overcoming the pressure loss through:  
On demand water heater (reference flow vs. pressure curve of the model  
being used)  
Optional storage tank (reference manufacturer’s information)  
All building supply and return plumbing in the circulation loop (reference  
local plumbling codes, standards, or practices)  
NOTE: Only use pumps of brass or stainless steel construction. Do not use pumps of iron  
construction as they will oxidize and clog the inlet filter on the appliance.  
9
Tank Water Heaters in a Circulation Loop  
The following applies when using a tank water heater (gas or electric) to provide heat for a circulation  
loop. Drawing H-1-RP is an example.  
The heat output of the tank must be equal to or greater than the calculated circulation loop heat loss.  
(Reference page 5, Step 1 on calculating heat loss).  
Electric Tank Water Heater  
Since the input and output are the same for an electric tank water heater, this can be expressed as:  
Electric Tank Input (Kw) > Circulation loop heat loss (Btu/h)  
3413  
(1 Kilowatt = 3,413 BTU)  
Gas Tank Water Heater  
When using a gas style water heater, the efficiency of the tank must be taken into account.  
Available Btu output = (Btu input of tank) x (efficiency) > Circulation loop heat loss (Btu/h)  
Example:  
30,000 Btu input gas tank  
0.62 Efficiency  
30,000 x .62 = 18,600 available Btu output  
Additional Guidelines  
On-demand water heaters not recovering a storage tank: In applications involving a commercial  
dishwasher, a hot water circulation loop feeding the dishwasher is required.  
On-demand water heater recovering a storage tank: In applications involving a commercial dishwasher,  
a hot water circulation loop feeding the dishwasher may be required depending on the distance between  
the dishwasher and the storage tank. Refer to local codes when determining the need for circulation  
loops to dishwashers.  
10  
Pump Sizing for Storage Tank Application  
The following applies when using on-demand water heaters to recover a storage tank.  
Drawing H-1-TC is an example.  
On-Demand water heaters have a pressure loss which must be considered in the system design.  
Reference the pressure loss curve for the heater model being used to determine the pump size for the  
desired recovery rate.  
For recommended pump sizes use the table below. Additional pressure losses in plumbing between the  
Heater(s) and the storage tank must also be taken into consideration.  
The specified pump size is to provide maximum recovery of the storage tank. A smaller pump size may  
be used, but could result in longer recovery time of the tank. Please contact the Tech Services department  
with any questions on pump sizing.  
NOTE: Only use pumps of brass or stainless steel construction. Do not use pumps of iron  
construction as they will oxidize and clog the inlet filter on the appliance.  
Pump Flow Requirements  
Number of  
On-Demand  
305  
705/505  
Water Heaters  
1
2
6 gpm @ 30' head  
12 gpm @ 30' head  
18 gpm @ 30' head  
24 gpm @ 30' head  
30 gpm @ 30' head  
36 gpm @ 30' head  
42 gpm @ 30' head  
48 gpm @ 30' head  
54 gpm @ 30' head  
60 gpm @ 30' head  
66 gpm @ 30' head  
72 gpm @ 30' head  
78 gpm @ 30' head  
84 gpm @ 30' head  
90 gpm @ 30' head  
5 gpm @ 25' head  
10 gpm @ 25' head  
15 gpm @ 25' head  
20 gpm @ 25' head  
25 gpm @ 25' head  
30 gpm @ 25' head  
35 gpm @ 25' head  
40 gpm @ 25' head  
45 gpm @ 25' head  
50 gpm @ 25' head  
55 gpm @ 25' head  
60 gpm @ 25' head  
65 gpm @ 25' head  
70 gpm @ 25' head  
75 gpm @ 25' head  
3
4
5
6
7
8
9
10  
11  
12  
13  
14  
15  
Table “C”  
11  
100/101 Series  
Pressure Loss Curves  
Pressure Loss (ft head)  
505  
305i  
305e  
Pressure Loss (psi)  
Figure “4”  
12  
200/201 Series  
Pressure Loss Curves  
Pressure Loss (ft head)  
705  
505  
305  
Pressure Loss (psi)  
Figure “5”  
13  
On-Demand  
Equipment List  
QTY  
1
On-Demand  
Water Heaters  
On-Demand  
Water Heater  
Gas Supply  
3/4” Cold Water Supply Line  
3/4” Hot Water Supply Line  
Domestic Hot Water - Standard Installation  
1 On-Demand Water Heater  
Preferred Piping Installation  
Key  
Pressure Regulator  
Circulating Pump  
Check Valve  
Boiler Drain Valve  
Solenoid Valve  
3/4" Ball Valve  
3/4" Union  
S
Mixing Valve  
Pressure Relief Valve  
Drawing Date:  
NOTE: This drawing is not intended to describe a complete system and is not a replacement for a pro-  
fessional engineering drawing. It is intended only as a guide and does not imply compliance with local  
building code requirements. Confer with local building officials before installation. The Contractor or  
engineer is to determine the necessary components and configuration of the particular system to be in-  
stalled. It is the responsibility of the engineer or contractor to ensure that the installation is in accordance  
with all local building codes.  
September 07, 2008  
Drawing Number:  
H-1  
14  
On-Demand  
Equipment List  
QTY  
2
On-Demand  
Water Heaters  
Electronic Connection *  
* Refer to On-Demand Accessories  
and Model Applicability for  
electronic connection details.  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
Primary  
Sub 1  
Gas Supply  
Cold Water Supply Line  
Hot Water Supply Line  
Domestic Hot Water - Standard Installation  
2 On-Demand Water Heaters  
Preferred Piping Installation  
Key  
Pressure Regulator  
Circulating Pump  
Check Valve  
Boiler Drain Valve  
3/4" Ball Valve  
3/4" Union  
S
Mixing Valve  
Solenoid Valve  
Pressure Relief Valve  
Drawing Date:  
NOTE: This drawing is not intended to describe a complete system and is not a replacement for a pro-  
fessional engineering drawing. It is intended only as a guide and does not imply compliance with local  
building code requirements. Confer with local building officials before installation. The Contractor or  
engineer is to determine the necessary components and configuration of the particular system to be in-  
stalled. It is the responsibility of the engineer or contractor to ensure that the installation is in accordance  
with all local building codes..  
September 07, 2008  
Drawing Number:  
H-2  
15  
On-Demand  
Equipment List  
QTY  
3
On-Demand  
Water Heaters  
Electronic Connection *  
* Refer to On-Demand Accessories  
and Model Applicability for  
electronic connection details.  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
Primary  
Sub 1  
Sub 2  
Gas Supply  
Cold Water Supply Line  
Hot Water Supply Line  
Domestic Hot Water - Standard Installation  
3 On-Demand Water Heaters  
Preferred Piping Installation  
Key  
Pressure Regulator  
Circulating Pump  
Check Valve  
Boiler Drain Valve  
3/4" Ball Valve  
3/4" Union  
S
Mixing Valve  
Solenoid Valve  
Pressure Relief Valve  
Drawing Date:  
NOTE: This drawing is not intended to describe a complete system and is not a replacement for a pro-  
fessional engineering drawing. It is intended only as a guide and does not imply compliance with local  
building code requirements. Confer with local building officials before installation. The Contractor or  
engineer is to determine the necessary components and configuration of the particular system to be in-  
stalled. It is the responsibility of the engineer or contractor to ensure that the installation is in accordance  
with all local building codes.  
September 07, 2008  
Drawing Number:  
H-3  
16  
On-Demand  
Equipment List  
QTY  
4
On-Demand  
Water Heaters  
Electronic Connection *  
* Refer to On-Demand Accessories  
and Model Applicability for  
electronic connection details.  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
Sub 1  
Sub 2  
Sub 3  
Primary  
Gas Supply  
Cold Water Supply Line  
Hot Water Supply Line  
Domestic Hot Water - Standard Installation  
4 On-Demand Water Heaters  
Preferred Piping Installation  
Key  
Pressure Regulator  
Circulating Pump  
Check Valve  
Boiler Drain Valve  
3/4" Ball Valve  
3/4" Union  
S
Mixing Valve  
Solenoid Valve  
Pressure Relief Valve  
Drawing Date:  
NOTE: This drawing is not intended to describe a complete system and is not a replacement for a pro-  
fessional engineering drawing. It is intended only as a guide and does not imply compliance with local  
building code requirements. Confer with local building officials before installation. The Contractor or  
engineer is to determine the necessary components and configuration of the particular system to be in-  
stalled. It is the responsibility of the engineer or contractor to ensure that the installation is in accordance  
with all local building codes.  
September 07, 2008  
Drawing Number:  
H-4  
17  
On-Demand  
Equipment List  
QTY  
5
On-Demand  
Water Heaters  
Electronic Connection *  
* Refer to On-Demand Accessories  
and Model Applicability for  
electronic connection details.  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
On-Demand  
Water Heater  
Primary  
Sub 1  
Sub 2  
Sub 3  
Sub 4  
Gas Supply  
Cold Water Supply Line  
Hot Water Supply Line  
Domestic Hot Water - Standard Installation  
5 On-Demand Water Heaters  
Preferred Piping Installation  
Key  
Pressure Regulator  
Circulating Pump  
Check Valve  
Pressure Relief Valve  
Boiler Drain Valve  
Solenoid Valve  
3/4" Ball Valve  
3/4" Union  
S
Mixing Valve  
Drawing Date:  
NOTE: This drawing is not intended to describe a complete system and is not a replacement for a pro-  
fessional engineering drawing. It is intended only as a guide and does not imply compliance with local  
building code requirements. Confer with local building officials before installation. The Contractor or  
engineer is to determine the necessary components and configuration of the particular system to be in-  
stalled. It is the responsibility of the engineer or contractor to ensure that the installation is in accordance  
with all local building codes.  
September 07, 2008  
Drawing Number:  
H-5  
18  
On-Demand  
Equipment List  
QTY  
6
On-Demand  
Water Heaters  
Electronic Connection *  
* Refer to On-Demand Accessories  
and Model Applicability for  
electronic connection details.  
On-  
On-  
On-  
On-  
On-  
On-  
Demand  
Demand  
Demand  
Demand  
Demand  
Demand  
Water  
Water  
Water  
Water  
Water  
Water  
Heater  
Heater  
Heater  
Heater  
Heater  
Heater  
Sub 1  
Primary  
Sub 2  
Primary  
Sub 1  
Sub 2  
Gas Supply  
Pressure Regulator  
Set to 5 PSI Below  
Street Pressure  
Hot Water Supply Line  
Cold Water Supply Line  
Domestic Hot Water - Standard Installation  
6 On-Demand Water Heaters  
Preferred Piping Installation  
Key  
Pressure Regulator  
Circulating Pump  
Check Valve  
Boiler Drain Valve  
3/4" Ball Valve  
3/4" Union  
S
Mixing Valve  
Solenoid Valve  
Pressure Relief Valve  
Drawing Date:  
NOTE: This drawing is not intended to describe a complete system and is not a replacement for a pro-  
fessional engineering drawing. It is intended only as a guide and does not imply compliance with local  
building code requirements. Confer with local building officials before installation. The Contractor or  
engineer is to determine the necessary components and configuration of the particular system to be in-  
stalled. It is the responsibility of the engineer or contractor to ensure that the installation is in accordance  
with all local building codes.  
September 07, 2008  
Drawing Number:  
H-6  
19  
IMPORTANT!  
With electrical power supplied to a on-demand water heater, it will not freeze  
in enviornments as cold as -30 F, when protected from direct wind exposure.  
On-Demand  
Equipment List  
º
QTY  
1
In the event of a power failure at temperatures below freezing, the water  
heater should be drained of all water to prevent freezing damage.  
Outdoor On-Demand  
Water Heater  
The unit may be drained manually or through the installation of the  
Optional solenoid valves as shown.  
The electrical connections for the two solenoid valves should be tied to  
the 120 V power terminals provided on the PC Board of the water heater.  
When the electrical power to the water heater fails, the cold water supply  
Vacuum  
Breaker  
drain down solenoid valve opens, allowing the water heater and  
associated piping to drain. Ensure that you run the drain for the solenoids  
per local codes.  
Outdoor  
On-Demand  
Water Heater  
NOTE:  
enclosure or recess box and packed with insulation