UHD S
TANDARD
D
UCT
F
URNACE
I
NSTALLATION
O
PERATION
AND
S
ERVICE
M
ANUAL
22
Figure 11: Automatic Burner Control Sequence
Figure 12: Gas Valve
B
u
rner Se
qu
ence for Ignition Control
Flame Signal
Start Gas
V
al
v
e
Ignition Spark
Thermostat 24
V
SHUT DO
WN
RU
N
START
ts = 10 Seconds
Signals O
u
tp
u
t By Control
Re
qu
ired Incoming Signals
Fl
u
e Blo
w
er
Press
u
re
S
w
itch
P
C
N
O
N
C
30 Seconds P
u
rge*
*P
u
rge time
b
egins at press
u
re s
w
itch change o
v
er.
30 Seconds Post P
u
rge
If at any stage the flame fails, the control will retry
for ignition. The control has four trials for ignition
before a one hour lockout.
½PSI
I
N
C
O
N
OFF
Reg
u
lator
O
u
tlet
Press
u
re
Gas Inlet
Inlet Press
u
re
TOP VIEW
END VIEW
Description
Part Number
Gas Valve 150 - 225 NG
90032505
Gas Valve 150 - 225 LP
90032506
Gas Valve 250 - 400 NG
90032520
Gas Valve 250 - 400 LP
90032521
