GSA
Gas-Fired Steam Boilers –
Boiler Manual
17
Part Number 550-110-738/0703
Figure 14
Wiring diagram — Standing pilot system
9
Sequence of operation
Follow all procedures given in this manual and “Lighting Instructions” when
oper
ating the boiler
. F
ailure to do so could result in se
v
ere personal injur
y,
death or substantial proper
ty damage
.
1.
Standby mode:
After pilot is manually lighted, the gas valve provides pilot gas and
maintains pilot as long as the thermocouple is satisfied. If thermocouple signal drops
for any reason, pilot must be manually lighted, following the “Lighting Instructions” in
this manual and on boiler
. V
ent damper will remain closed until a call f
or heat.
2.
Call f
or heat:
When ther
mostat circuit closes
, the boiler v
ent damper is energiz
ed.
The v
ent damper dr
iv
es open.
When the v
ent damper is fully open, its end s
witch
energiz
es the main gas v
alv
e
. This pro
vides gas to the main b
u
rners
. Bur
ners remain
ignited until thermostat circuit or limit circuit opens. Burners are deenergized when call
for heat stops.
3.
Limit operation:
When a limit control opens
, the main gas v
alv
e is deenergiz
ed.
When
the limit circuit closes again, the main gas valve is energized if there is still a call for
heat.
4.
Thermostat heat anticipator:
Set heat anticipator as shown on wiring diagram,
Figure 14.