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Service Manual
33
FIG. 32 Water Connections
Relief Valve
This unit is supplied with a relief valve(s) sized in accordance
with ASME Boiler and Pressure Vessel Code, Section IV
(“Heating Boilers”). The relief valve(s) is installed in the
vertical position and mounted in the hot water outlet. Place no
other valve between the relief valve and the unit. To prevent
water damage, pipe the discharge from the relief valve to a
suitable floor drain for disposal when relief occurs. Do not
install any reducing couplings or other restrictions in the
discharge line. The discharge line will allow complete drainage
of the valve and line. Manually operate the relief valves at least
once a year.
Water Flow Switch
A water flow switch is factory installed. The flow switch is
wired in series with the 24 VAC safety control circuit at the
FIG. 33 Control Panel Component Location Drawing
units terminal strip. This wiring connection installs the flow
switch in the 24 VAC safety circuit to prove water flow before
main burner ignition. The factory supplied flow switch is
installed in the outlet side of the front header. The 399,999 -
750,000 units require a minimum flow of 15 - 18 GPM
whereas the 990,000 - 2,070,000 units require a minimum flow
of 26 GPM to make the flow switch and start burner operation.
Ensure that the pump installed on the unit will supply adequate
flow to make the flow switch contacts and operate the unit. A
water flow switch meets most code requirements for a
low-water cut off device on appliances requiring forced
circulation for operation.
Low Water Cutoff
(If Equipped)
If installing this unit above radiation level, you must install a
low water cut-off device at the time of appliance installation.
Electronic or float type low water cutoff controls are available
as a factory supplied option on all units. Inspect the low water
cutoff every six months, including flushing of float types. The
low water cutoff control is located on the control panel directly
behind the control panel cover.
The reset and test buttons (if equipped) are located on the
control panel cover.
CONNECTING TO
ELECTRICAL SUPPLY
This unit is wired for 120 VAC service. The unit, when
installed, must be electrically grounded in accordance with the
requirements of the authority having jurisdiction or in the
absence of such requirements, with the latest edition of the
National Electrical Code ANSI/NFPA No. 70. When the unit is
installed in Canada, it must conform to the CAE C22.1,
Canadian Electrical Code, Part 1 and/or local Electrical Codes.
2-1/2" NPT
WATER OUTLET
2-1/2" NPT
WATER INLET
INSPECTION
PLUGS
ƽ CAUTION: Avoid contact with hot
discharge water.