25
Finned copper tube gas boilers & water heaters – Boiler manual
FTXLF-IOM-HN-1-110308 Copyright 2008 Mestek, Inc.
HeatNet Control Panel
Figure 17
seQUence oF operAtion
no DemAnD
standby
The boiler is idle with no interlocks in the fault condition.
1.
DemAnD
pre-purge
The blower operates at purge RPM. The water flow interlock must
1.
‘make’ within 15 seconds after the demand signal is initiated.
The Honeywell 7800 starts a 10 second purge delay once the air
2.
prove switch contacts close.
pilot run - %Input
The blower operates at minimum ignition setting. See the calibra-
1.
tion section in the “HeatNet Control-IOM” to enter the calibra-
tion menus.
The ignition transformer is energized. The pilot solenoid valve
2.
opens for the 10 second pilot ignition trial.
Main run %Input
The main gas valve opens.
1.
The ignition transformer is de-energized.
2.
The pilot solenoid valve closes.
3.
The blower stays at the minimum input setting for
4.
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
The main gas valve closes.
1.
The blower operates at purge RPM for 10 seconds.
2.
The boiler is idle with no interlocks in the fault condition.
3.
