Rheem Raypak Hi Delta P902C Installation & Operating Instructions Manual page 44

High and Low Gas Pressure Switches
The low gas pressure switch (standard) connection
mounts upstream of the gas valve to ensure that suffi-
cient gas pressure is present for proper regulator
performance. The low gas pressure switch automati-
cally shuts down the heater if gas supply drops below
the factory setting of 5.0 in. WC for natural gas, and
10.0 in. WC for propane gas.
The high gas pressure switch (Sales option S-2) con-
nection mounts down-stream of the stage-1 gas valve.
If the gas pressure regulator fails, the high gas pres-
sure switch automatically shuts down the burner. The
high gas pressure switch automatically shuts down the
heater if gas manifold pressure rises above the setting
of 5.0 in. WC for natural gas, and 11.5 in. WC for
propane gas. These safety devices can emit small
amounts of fuel gas, and must be vented to a safe dis-
charge location outdoors, per local code requirements.
Fig. 48: High/Low Gas Pressure Switch
Air Pressure Switch
This heater is equipped with a one or more air pres-
sure switches to prove blower operation prior to
ignition. This switches are located on the blower hous-
ing.
Fig. 49: Air Pressure Switch
Blocked Vent Switch
This heater is equipped with a blocked vent pressure
switch to prevent the operation of the heater when too
much of the vent is blocked. This switch is located
inside the left upper cabinet adjacent the control box.
Fig. 50: Blocked Vent Switch
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