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SECTION 10: OPERATION AND MAINTENANCE
31
Figure 18: Gas Valve for Models UHA[X][S] 60 - 125
10.2.2 Start-Up the Gas Valve (All Gases)
10.2.2.1 Check Burner Gas Pressure
1. Remove the plug in the outlet (burner) pressure
test point and connect a pressure tap and a
manometer.
2. With the burner firing, measure the pressure on
the manometer. To adjust the burner pressure,
remove the regulator cover from the valve and
turn the regulator adjustment screw to set the
required burner pressure as stated in the
Technical Data Tables for the correct gas and
model on Page 50, Section 15.3.
IMPORTANT: If the correct burner pressure cannot
be reached, then check the inlet pressure to the
valve with the burner firing. See Technical Data
Table s on Page 50, Section 15.3 for inlet pressure
requirement.
Do not continue to adjust the regulator if the
pressure is not changing.
If the inlet pressure is too low to allow correct burner
pressure setting, then the gas inlet pressure must be
corrected before completing the start-up.
Check Gas Rate
1. After burner pressure adjustment, allow the
heater to operate for at least 15 minutes and
then re-check settings. Adjust pressure setting
if necessary.
2. Check gas flow rate at gas meter.
3. Turn off heater and electrical supply.
4. Remove the manometer and refit all covers to
the valve and tighten the screw of the outlet
pressure tap.
10.2.3 Pressure Switch
The pressure switch is factory pre-set for each
model and is not adjustable.
10.2.4 Turning Off the Heater
Set the thermostat to the "OFF" position or lowest
setting and the main burner will stop.
The fan will continue to run for 90 seconds.
Do not use a disconnect switch for control of
heater. Disconnect switch will turn off the fan.
½PSI IN
C
ON
OFF
Regulator
Outlet
Pressure
Gas Inlet
Inlet Pressure
TOP VIEW
END VIEW
Description Part Number
Gas Valve 60 - 125 NG 90032505
Gas Valve 60 - 125 LP 90032506