Blower Speed Control - Suf 119300 Thru 119500 - State Water Heaters 60120-100250 Service Handbook

BLOWER SPEED CONTROL – SUF 119300 THRU 119500
The CCB monitors a feedback signal from a sensor that is installed on the blower. The CCB interprets the
pulse signal from the sensor and then sends a signal to the variable frequency drive (VFD) which in turn
transmits the proper frequency to the blower to produce the proper blower speed and input. Refer to the
Variable Frequency Drive on next page for its operation.
Below is a chart for the blower rpms and corresponding VFD Hertz Readings for those rpms displayed on
the VFD.
Note: These models are capable of modulating their input rate. Therefore, the RPM readings can be in
between the Heating Speed and Minimum Modulation Speed RPMs. The input rate should be verified
with the water heater operating at full input rate.
Model
SUF 119300 Nat
SUF 119300 LP
SUF 119400 Nat
SUF 119400 LP
SUF 119500 Nat
SUF 119500 LP
40
Heating Heating
Speed Speed
RPM VFD Hertz
Reading
3450 117.4
3200 108.8
4625 158.3
4200 143.2
5750 198.2
5225 179.8
Servicing should only be performed by a Qualified Service Technician
Minimum Minimum
Modulation Modulation
RPM VFD Hertz
Reading
2350 79.7
2310 78.5
2350 79.7
2310 78.5
2350 79.7
2310 78.6
Ignition Ignition
Speed Speed
RPM VFD Hertz
Reading
4500 153.8
5770 198.2
4500 153.8
5770 198.2
4500 153.8
5770 198.2