Installing the water heater.
Typical Installation
Thermal Expansion
Determine if a check valve exists in the
inlet water line. Check with your local
water utility. It may have been installed in
the cold water line as a separate back flow
preventer, or it may be part of a pressure
reducing valve, water meter or water softener.
A check valve located in the cold water inlet
line can cause what is referred to as a “closed
water system”. A cold water inlet line with
no check valve or back flow prevention
device is referred to as an “open” water
As water is heated, it expands in volume and
creates an increase in the pressure within the
water system. This action is referred to as
“thermal expansion”. In an “open” water
system, expanding water which exceeds the
capacity of the water heater flows back into
the city main where the pressure is easily
A “closed water system”, however, prevents
the expanding water from flowing back
into the main supply line, and the result of
“thermal expansion” can create a rapid
and dangerous pressure increase in the water
heater and system piping. This rapid pressure
increase can quickly reach the safety setting
of the relief valve, causing it to operate during
each heating cycle. Thermal expansion, and
the resulting rapid and repeated expansion
and contraction of components in the water
heater and piping system can cause premature
failure of the relief valve, and possibly the
heater itself. Replacing the relief valve will
not correct the problem!
The suggested method of controlling thermal
expansion is to install an expansion tank in
the cold water line between the water heater
and the check valve (refer to the illustration
below). The expansion tank is designed
with an air cushion built in that compresses
as the system pressure increases, thereby
relieving the over pressure condition and
eliminating the repeated operation of the
relief valve. Other methods of controlling
thermal expansion are also available. Contact
your installing contractor, water supplier or
plumbing inspector for additional information
regarding this subject.
NOTICE: Do not apply
heat to the HOT or COLD
water connections. If sweat
connections are used, sweat
tubing to adapter before
fitting adapter to the water
connections on heater.
Any heat applied to the
water supply fittings will
permanently damage the
dip tube and/or heat traps.
Water Supply Connections
Refer to the illustration below for suggested
typical installation. The installation of
unions or flexible copper connectors is
recommended on the hot and cold water
connections so that the water heater may
be easily disconnected for servicing if
necessary. The HOT and COLD water
connections are clearly marked and are 3/4
NPT on all models. Install a shut-off valve
in the cold water line near the water heater.
Heat trap
6 " m i n i m u m
Heat trap
6 " m i n i m u m
6 " a i r g a p
U n i o n
T o electrical
d i s t r i b u t i o n p a n e l Te m p e r a t u r e
Pressu re
R e l i e f Va l v e
A n o d e
U n i o n
H o t w a t e r o u t l e t
t o f i x t u r e s
Jack et access
p a n e l s
D r a i n v a l v e
A u x i l i a r y c a t c h p a n
2 " m a x i m u m
R e l i e f v a l v e d i s c h a r g e l i n e
t o s u i t a b l e o p e n d r a i n
Th ermal
ex p a n s i o n t a n k
(if req u ired )
E l e c t r i c a l j u n c t i o n b o x
( u s e o n l y c o p p e r c o n d u c t o r s )
T o co ld water
s u p p l y
S h u t - o f f
va l v e
Vacuum Relief Valve
(Not Supplied)
If required, install per local codes
and valve manufacturer’s
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