Closed Water Systems; Thermal Expansion - State Water Heaters she50 Instruction Manual

• The hot water line from the water heater should be vertical past
any mixing valve or supply line to the heating system to remove
air bubbles from the system.
• Do not connect the water heater to any system or components
previously used with non-potable water heating appliances when
used to supply potable water.
• These water heaters cannot be used in space heating applications
only.

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
flow 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 grow when it is heated. As the volume of
water grows 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. This condition is not
covered under the limited warranty. The temperature-pressure relief
valve is not intended for the constant relief of thermal expansion.
A properly sized thermal expansion tank should be installed on all
closed systems to control the harmful effects of thermal expansion.
fIGure 9.
note: to protect against untimely corrosion of hot and cold
water fittings, it is strongly recommended that di-electric unions
or couplings be installed on this water heater when connected
to copper pipe, see figure 10 also.
Figures 9 and 10 show the typical attachment of the water piping to
the water heater. The water heater is equipped with 3/4 inch NPT
water connections.
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.
t & p valve and pipe Insulation (if supplied)
Remove insulation for T & P valve and pipe connections from
carton.
16
fIGure 10.
fIGure 11.