Question about Harman P43 combustion blower voltage

[PJPellet]

Hi guys,
Tonight I am playing around with the pellet stove. I noticed something interesting and hopefully someone can explain it to me. When the stove first starts up the combustion blower voltage is 119 volts, then after a while it drops a few volts at a time until it gets down to 97 volts and then it stays there until it needs to fire up again where it then jumps up to 119 volts again. Then the cycle starts all over again. Just wondering why the stove does this. My guess is to prevent an over-fire situation as I notice it happens around 315* according to the esp probe in the exhaust. Can anyone explain the Harman combustion blower workings. I was under the impression that the combustion blower always ran at the same voltage. Thanks!

Interestingly when the voltage is at 97 volts and I adjust the trim pot on the control board it can be adjusted down to 44 volts, whereas when it's at 119 volts it can only be adjusted down to 109 volts. Yep, I'm bored tonight.

 

[PJPellet]

bumpety-bump-bump look at Frosty go!

 

[archie79]

Sounds to me like the blower starts up at full speed to get going well, It could even be alittle bleed from the capasitor on the motor (if it has one) It drops back to 97 volts cause it is regulating itself to run at a certain speed. Just about any electronic that isn't regulated with a rheostat starts up full blast before the circuit boards cuts back to whatever it needs.

 

[SmokeyTheBear]

The combustion blower voltage is controlled by the control board. I varies depending upon how many pellets are being fed to the burn pot. It goes up and it goes down. The adjustment pot is to match the control board to local line voltage and was set at the plant for 120 volts.

 

[PJPellet]

Excellent. Thank You. That makes sense.