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Finned copper tube gas boilers & water heaters – Boiler Manual
25
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Figure 17
HeatNet Control Panel
SEQUENCE OF OPERATION
NO DEMAND
Standby
1. Th e boiler is idle with no interlocks in the fault condition.
DEMAND
Pre-Purge
1. Th e blower operates at purge RPM. Th e water fl ow interlock must
‘make’ within 15 seconds aft er the demand signal is initiated.
2. Th e Honeywell 7800 starts a 10 second purge delay once the air
prove switch contacts close.
Pilot Run - %Input
1. The blower operates at minimum ignition setting. See the
calibration section in the “HeatNet Control-IOM” to enter the
calibration menus.
2. Th e ignition transformer is energized. Th e pilot solenoid valve
opens for the 10 second pilot ignition trial.
Main Run %Input
1. Th e main gas valve opens.
2. Th e ignition transformer is de-energized.
3. Th e pilot solenoid valve closes.
4. The blower stays at the minimum input setting for
3 seconds then operates at demand % input. See the calibration
section in the “HeatNet Control IOM” to enter the calibration
menus.
NO DEMAND
Post-Purge
1. Th e main gas valve closes.
2. Th e blower operates at purge RPM for 10 seconds.
3. Th e boiler is idle with no interlocks in the fault condition.
