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Closed System/Thermal Expansion
CAUTION - PROPERTY DAMAGE HAZARD
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.
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.
A suitable metal drain pan
should be installed under
the storage tank.
Storage Tank
6
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.
1-3/4”
max.
At least 2” greater than
the storage tank.
Pipe to an
adequate drain
Figure “1”
Hot Water
Outlet
In a closed system use a
thermal expansion tank
Cold Water
Inlet Valve
Pressure Reducing
Valve with Bypass
Main Water
Supply
Cold Water Supply
to Fixture
Temperature and
Pressure Relief Valve
Discharge line
6” Max. above drain
Drain line 3/4”
ID Min.
Drain
1“ Min.
Metal Drain
Pan 1-3/4”
Depth Max.
Massachusetts:
Install a vacuum relief
in cold water line per
section 19 MGL 142
Typical water
piping installation
Figure “2”
Storage
Tank
Hot Water
Return Line