Addison UHA 150, Installation, Operation & Service Manual

Page: 36 / 62

UHA S
TANDARD
U
NIT
H
EATER
I
NSTALLATION
O
PERATION AND
S
ERVICE
M
ANUAL
28 of 49
11.2 Be g in Start-Up
11.2.1 Before Operatin g the Heater
To ens u re that all the controls are in safe w orking
order, operate the heater for the first time w ith the
isolating gas valve t u rned off and po w er s u pply
t u rned on.
1. T u rn off the isolating gas valve.
2. T u rn u p the thermostat a b ove room
temperat u re. The a u tomatic ignition
seq u ence w ill no w b egin as descri b ed
on Page 28, Figure 13 .
There w ill b e no ignition of the bu rner and locko u t
w ill occ u r, w hich proves the controls are operating
correctly.
Fi g ure 13: Automatic Burner Control Se q uence
Burner Se q uence 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 Output By Control
Re q uired Incoming Signals
Flue Blower
Pressure
Switch
P
C
N O
N C
30 Seconds Purge*
*Purge time begins at pressure switch change o v er.
Axial Fan
30 Seconds Delay 90 Seconds Delay
30 Seconds Post Purge
If at any stage the flame fails, the control w ill retry
for ignition. The control has fo u r trials for ignition
b efore a one ho u r locko u t.