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Part number 550-142-054/0411
13
GV90+ gas-fired water boiler — Boiler Manual
Install water piping (continued)
Figure 13 Relief valve installation guidelines
To avoid water damage or scalding
due to relief valve operation, as
per local or state codes
:
Discharge line must be connected
to relief valve outlet and run to a
safe place of disposal. Terminate the
discharge line in a manner that will
prevent possibility of severe burns
or property damage should the valve
discharge.
Discharge line must be as short as
possible and be the same size as the
valve discharge connection through-
out its entire length.
Discharge line must pitch downward
from the valve and terminate at least
6” above the floor drain where any
discharge will be clearly visible.
The discharge line shall terminate
plain, not threaded, with a mate-
rial serviceable for temperatures of
375°F or greater.
Do not pipe the discharge to any
place where freezing could occur.
No shutoff valve shall be installed
between the relief valve and boiler,
or in the discharge line. Do not
plug or place any obstruction in the
discharge line.
Test the operation of the valve after
filling and pressurizing system by
lifting the lever. Make sure the valve
discharges freely. If the valve fails to
operate correctly, replace it with a
new relief valve.
Failure to comply with the above
guidelines could result in failure of
the relief valve to operate, resulting
in possibility of severe personal in-
jury, death or substantial property
damage.
Expansion tank
Figure 14, page 14 and Figure 15, page 14 show typical installation of the
expansion tank. Always locate the air separator and expansion tank as
shown in the suggested piping drawings, beginning with Figure 17, page 16.
Ensure that the expansion tank size will handle boiler and system water
volume and temperature. See tank manufacturer’s instructions and rat-
ings for details. Additional tanks may be added to the system if needed to
handle the expansion. These tanks may be installed by connecting to tees
in the system piping.
Undersized expansion tanks cause system water to be lost
from the relief valve and makeup water to be added through
the fill valve. Eventual section failure can result. Always locate
the cold water fill connection at the expansion tank. Never
locate this elsewhere in the system.
Diaphragm- or bladder-type tank:
Refer to Figure 14, page 14 for suggested piping when using a diaphragm-
or bladder-type expansion tank.
Diaphragm- or bladder-type expansion tank — Control
fill pressure with the tank air charge pressure. Always check
pressure and charge tank with tank removed from system
to be sure reading is accurate. Boiler relief valve is set for 30
PSIG. Operating pressure of system, after temperature expan-
sion above cold fill pressure, should not exceed 24 PSIG to
avoid weeping of relief valve.
Install an
automatic air vent on top of the air separator, per separator
manufacturer’s instructions.
Closed-type expansion tank:
Figure 15, page 14 shows suggested piping when using a closed-type expan-
sion tank, in which the air is directly in contact with tank water.
Connect piping (½” or ¾”) from the air separator top outlet to the tank
fitting. Slope any horizontal piping a minimum of 1 inch per 5 feet of
horizontal pipe.
Always use a
tank fitting, such as the B&G Tanktrol or Taco Taco-Trol
(shown). The fitting reduces gravity flow of water in the piping to the
tank, avoids air bubbling through the tank water, and provides the proper
fill height in the tank.
Correct all leaks in the system or tank piping. Leaks allow
air to escape from the system and will cause water-logging
of the tank. This will result in water loss through the boiler
relief valve due to over-pressurization.
NEVER use an automatic air vent in a system equipped with a
closed-type expansion tank. The air removed from the system
will cause water-logging of the expansion tank.
Closed-type expansion tank — Follow tank manufacturer’s
instructions for filling the tank. Typical tank sizing provides
for approximately 12 PSIG when the tank is filled to the
normal level and system water is cold. Note that boiler relief
valve is set for 30 PSIG. Operating pressure of system, after
temperature expansion above cold fill pressure, should not
exceed 24 PSIG to avoid weeping of relief valve.