Closed Water Systems; Thermal Expansion - American Water Heater VG6250T100 Instruction 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
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.