Closed Water Systems; Thermal Expansion; Hard Water - A.O. Smith POWER VENT GAS Installation And Operating Manual

CLOSED WATER SYSTEMS

Water supply systems may, because of code requirements
or such conditions as high line pressure, among others,
have installed devices such as pressure reducing valves,
check valves, and back fl ow preventers. Devices such as
these cause the water system to be a closed system.

THERMAL EXPANSION

As water is heated, it expands (thermal expansion). In a
closed system, the volume of water will increase. As the
volume of water increases, there will be a corresponding
increase in water pressure due to thermal expansion.
Thermal expansion 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 temperature-pressure relief valve is not
intended for the constant relief of thermal expansion. This
condition is not covered under the limited warranty.
A properly-sized thermal expansion tank should be
installed on all closed systems to control the harmful
effects of thermal expansion. Contact a plumbing service
agency or your retail supplier regarding the installation of
a thermal expansion tank.
NOTE: If using copper tubing, solder tubing to an
adapter before attaching the adapter to the water
heater connections. Do not solder the water lines
directly to the water heater connections. It will harm
the dip tube and damage the tank.
316888-001 Rev. 00 dRaFt Jun 28 245
SHUT-OFF
VALVE
COLD WATER
INLET
NOTE: To protect against untimely corrosion of hot
and cold water fi ttings, it is strongly recommended
that di-electric unions or couplings be installed on
this water heater when connected to copper pipe (see
Figure 3 also).
Figures 3 and 16 show the typical attachment of the water
piping to the water heater. The water heater is equipped
with 3/4" NPT water connections.

HARD WATER

We highly recommend installing water fi ltering system or
a water softener before the water heater system. If you
are installing a water fi ltering system use a 5 micron fi lter
to reduce particles that can potentially cause nuisance
shutdown problems and prolong the maintenance of the
water heater's inlet fi lter. A water softener can affect the
life of the anode installed in this water heater. Refer to
"Anode Rod Inspection" section in this manual.
Clean the fi lter on the water inlet as frequently as required
by the quality of your local water. Refer to "Cleaning The
Inlet Water Filter" section of this manual. One additional
fi lter is supplied with your water heater.
www.hotwater.com
TEMPERED
POTABLE WATER
MIXING
VALVE
(OPTIONAL)
PIPE INSULATION
(RECOMMENDED)
Rear View
FIGURE 16
15