ProFire PF2200-SB Product Manual page 35

2.2.9.2 STAGED HEATING
Staged Heating Mode is a slightly more advanced method of control than the On/Off control, allowing
an extra stage of heating. In this mode, the system utilizes the HFV output as another heating level –
giving the system a total of three stages:
• Pilot Only (Pilot)
Pilot + SSVs (Stage 1)
•
Pilot + SSVs + HFV (Stage 2)
•
The diagram below outlines the behavior of the system in Two-Stage Control
1. When the process temperature is below the process setpoint the SSV and the HFV outputs will
be energized for maximum heat output
2. When the process temperature is above the process setpoint but below the main off setpoint
the SSV outputs will remain energized and the HFV outputs will be de-energized, reducing the
burner's firing rate.
3. When the process temperature exceeds the main off setpoint the SSV outputs de-energize. The
system will transition to the pilot state to cool down.
4. When the process temperature cools down to the process temperature setpoint minus the dead
band the SSV and the HFV outputs will be energized to heat the system back up
Note: this process control mode does not utilize the TCV output.
Section 2: PF2200-SB PRODUCT DESCRIPTION
V 4.0
Page 35 of 85