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BOILER SYSTEMS AND OPERATION
CONTROLLER MANUAL – SFC/SFB SERIES BOILERS
The SF series units include a factory installed and pre-wired pump. The pump
may not be able to supply adequate flow for the heat emitter circuits. A system
heating pump switched through a separate relay or control box may be needed.
SEQUENCE OF OPERATION
The boiler operates in a similar way for both a space heating and a domestic hot
water call for heat. When the boiler is powered up the controller enters a self-
diagnostic mode, and displays “2” in the Service Display.
The Sequence of Operation is as follows:
1 .
The boiler receives a call for heat from closing terminals X13.1 and X13.2
(24 volts section). The boiler can also receive a call from Domestic Hot Water
heating from the internal flow sensor, or from a 10KΩ sensor or aquastat
(X13.4 and X13.5 in 24V terminal).
2 .
The boiler does a safety check and energizes the fan for a pre-purge
(
Service Display = 3
).
3 .
Once the 5-second pre-purge is compete, the boiler enters a 5-second trial
for ignition (
Service Display = 4
). If the boiler fails to ignite, the boiler will
complete a 5-second inter-purge then another 5-second trial for ignition. This
is repeated 4 times before a hard lock-out occurs. The Return button must be
pressed to reset the controller and to allow for another attempt.
4 .
Once the burner is lit and flame has been proven the boiler operates as it is
programmed (
Service Display
= for Space Heating or
for Domestic
Hot Water).
5 .
If the boiler reaches its target temperature and there is still a call for heat
or hot water the Burner will turn off (integral pump runs unless call is on-
demand dhw ). (
Service Display = 1
)
6 .
After the call for heat is satisfied, the boiler pump will operate for an
adjustable amount of time (
Service Display = 0
).
7 .
If the burner is on to maintain the heat exchanger temperature for DHW
Comfort mode or for Freeze Protection mode (
Service Display = 7
).
8 .
If the burner is on to maintain the heat exchanger temperature for DHW
Comfort mode or for Freeze Protection mode (
Service Display = 7
).
