Sequence Of Operation - Lochinvar POWER-FIN PBN2500 Installation & Operation Manual

10
Operating information

Sequence of operation

Upon a call for heat, the control turns on the appropriate pumps (system and boiler pumps for a space heating call,
1.
HW pump for a hot water generator call).
2.
The control confirms that the low water cutoff contacts are closed and energizes the louvers (optional).
The control confirms that the gas pressure switch, blocked drain switch, limits, louver proving switch (optional) and
3.
contacts close. The Pre-Purge cycle begins.
4.
The control confirms the blower comes up to the desired speed, and the air pressure switch is closed.
Once the Pre-Purge cycle is complete, the control lowers the blower speeds, initiates sparking of the ignition
5.
electrode, and opens the gas valve.
After a short wait, the control stops sparking and checks for the presence of flame current through the flame sense
6.
electrode.
If the control does not detect flame current, the control will lockout indefinitely, until the RESET button on the touch
7.
screen LCD is pressed.
If the control detects flame current, the control will hold the blower speed constant for a few seconds to allow the
8.
flame to stabilize, then begin modulating the firing rate in order to maintain the controlling sensor to the desired set
point temperature.
If the current call for heat is for space heating and a HW call for heat becomes active, the control will turn on the HW
9.
pump relay output, then turn off the boiler pump. It will then modulate the blower speed in order to maintain the
outlet temperature to the desired HW outlet set point temperature.
Once both the space heating and HW calls for heat are satisfied, the control will turn off the gas valve(s) and begin
10.
the Post-Purge cycle. Any pumps that are running will begin their respective Pump Delay cycles.
11.
At the end of the Post-Purge cycle, the louver relay contacts will de-energize.
12.
At the end of the Pump Delay cycle(s), the pump(s) will be turned off.
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Installation & Operation Manual