Install Instructions

11 Operating information (continued)

OPERATION DISPLAY

6. If flame is detected, it holds the firing rate steady for a few

seconds to let the flame stabilize, then it begins to modulate the

firing rate based on a set point or some other command.

7. Combi Models Only: If the space heating call for heat is active

and the DHW flow switch starts a DHW call for heat, the diverter

valve will move to the DHW position and the boiler will switch to

the DHW Mode. This will divert the boiler's outlet water from the

heating system to the brazed plate heat exchanger. The control

will then modulate to maintain the DHW outlet temperature at the

DHW set point.

Boiler Models Only: If the space heating call for heat is active,

and the tank thermostat or sensor starts a DHW call for heat, the

boiler will switch to the DHW mode. If programmed for normal

DHW operation (not as a zone), the DHW pump will turn on first,

then the boiler pump will turn off (boiler and DHW pump operation

briefly overlap to ensure flow is maintained through the unit). This

will divert the boiler’s outlet water from the heating system and

send it to the tank coil instead. The control will then modulate to

maintain the outlet temperature to the DHW boiler set point.

8. Once all calls for heat are satisfied, the control will turn off

the burner. The blower will continue to run during the postpurge

period.

9. Any pumps that are running will continue to run for their

respective pump delay times before turning off. A 60 second

anti-cycle period will start, which will delay any new space

heating call for heat until it times out.

10. In Standby, ready to start a new cycle.

Installation & Service Manual

FIRE TUBE

™

Sequence of operation (continued)