UHA L
OW
P
ROFILE
U
NIT
H
EATER
I
NSTALLATION
O
PERATION
AND
S
ERVICE
M
ANUAL
30
Figure 16: Automatic Burner Control Sequence
Figure 17: Gas Valve for Models UHA[X][S] 30 - 45
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.
Axial Fan
30 Seconds Delay
90 Seconds Delay
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.
Press
u
re Reg
u
lator
Gas O
u
tlet
O
u
tlet Press
u
re
Description
Part Number
Gas Valve 30 - 45 NG
90034500
Gas Valve 30 - 45 LP
90034600
