SECTION 11: O
PERATION
AND
M
AINTENANCE
29 of 51
Fi
g
ure 14: Gas Valve for Models UHA[X][S] 150 - 400
11.2.2 Start-Up the Gas Valve (All Gases)
11.2.2.1 Check Burner Gas Pressure
1. Remove the pl
u
g in the o
u
tlet (b
u
rner) press
u
re
test point and connect a press
u
re tap and a
manometer.
2. With the b
u
rner firing, meas
u
re the press
u
re on
the manometer. To adj
u
st the b
u
rner press
u
re,
remove the reg
u
lator cover from the valve and
t
u
rn the reg
u
lator adj
u
stment scre
w
to set the
req
u
ired b
u
rner press
u
re as stated in the
Technical Data Table for the correct gas and
model
on Page 49, Section 16.3
.
NOTE:
If the correct b
u
rner press
u
re cannot be
reached, then check the inlet press
u
re to the valve
w
ith the b
u
rner firing. See Technical Data Table
on
Page 49, Section 16.3
for inlet press
u
re
req
u
irement.
Do not continue to adjust the re
g
ulator if the
pressure is not chan
g
in
g
.
If the inlet press
u
re is too lo
w
to allo
w
correct b
u
rner
press
u
re setting, then the gas inlet press
u
re m
u
st be
corrected before completing the start-
u
p.
Check Gas Rate
1. After b
u
rner press
u
re adj
u
stment, allo
w
the
heater to operate for at least 15 min
u
tes and
then re-check settings. Adj
u
st press
u
re setting
if necessary.
2. Check gas flo
w
rate at gas meter.
3. T
u
rn off heater and electrical s
u
pply.
4. Remove the manometer and refit all covers to
the valve and tighten the scre
w
of the o
u
tlet
press
u
re tap.
11.2.3 Pressure Switch
The press
u
re s
w
itch is factory pre-set for each
model and is not adj
u
stable.
11.2.4 Turnin
g
Off the Heater
Set the thermostat to the "OFF" position or lo
w
est
setting and the main b
u
rner
w
ill stop.
The fan
w
ill contin
u
e to r
u
n
u
ntil it is stopped
a
u
tomatically by the fan thermostat.
Do not use a disconnect switch for control of
heater. Disconnect switch will turn off the fan.
Heat exchan
g
er could be dama
g
ed. Warranty will
not cover dama
g
e to the heat exchan
g
er if
operated improperly. Only use the disconnect
switch for turnin
g
off heater for service or durin
g
off-season.
½PSI
I
N
C
O
N
OFF
Regulator
Outlet
Pressure
Gas Inlet
Inlet Pressure
TOP VIEW
END VIEW
Description
Part Number
Gas Valve 150 - 250 NG
90032505
Gas Valve 150 - 250 LP
90032506
Gas Valve 300 - 400 NG
90032520
Gas Valve 300 - 400 LP
90032521
