Exhaust Blower issues on St Croix Prescott EXL - Fan will NOT turn off

[two-if-by-sea]

Exhaust Blower issues on St Croix Prescott EXL - Fan will NOT turn off

I've got a St Croix Prescott EXL free-standing pellet stove. I bought it new in 2008, and other than an igniter, and a cracked door glass, it's been trouble-free for a LOT of years.

A few weeks ago, I was getting the flashing "3" on the control board. I did some research on here, and went ahead and bought a new exhaust fan and proof-of-fire switch (plus a new auger motor, but that's obviously not the issue here)

The stove has worked wonderfully over the last week, quieter than I ever remember it being, and all was well. We had a cold spell last week, and maybe I just never noticed, but yesterday I saw that the exhaust fan is not turning off. I turned the stove off at the thermostat to clean, and 3 hours later, the fan was still running. At first I thought it was the room fan (separate motor), but I went outside, and there is exhaust pumping out of the chimney.

A few other notes:
I replaced a fastco 712113177 (80P20001-R) with the exact same fastco part. Originally this stove was equipped with a 3-wire motor, and it was replaced with a 3-wire motor (black, white, brown). When I removed the old motor, I was surprised to see that the brown wire was not connected anywhere in my stove, and was tied around the other two wires. Vendor says that older stoves use 3-wire, newer stoves use 2-wire, and just not to plug in the brown wire.

Could the culprit here, be the proof of fire switch, or is likely something with the fan?
Any thoughts about what could be preventing the exhaust fan from not cutting off?
Control board?

 

[heat seeker]

I would unplug the stove for a few minutes to reset the control, first. Then, if that didn't work, I would disconnect one wire from the POF switch. That should shut the fans off. (A shorted POF switch would keep both fans running, at least on my Afton Bay.)

Assuming that you have a digital control, a flashing #3 light means the stove shut down for lack of fire. (Again, that's on my stove.)

IMO, the motor itself is not a fault. Disconnecting the POF switch will prove it guilty or not. That seems to leave the control, which may have a shorted triac on it. If you can solder on a board, it's a cheap and easy fix.

 

[two-if-by-sea]

I went ahead and got a new control board, and installed it.

The stove is now working fine, burning fine, not throwing codes. But the fans are still staying on, LONG after the stove shuts down. I'm talking 3 or 4 hours.

Previously, the room fans would stay on maybe an hour or so after the fire was out. The stove was still hot/warm, so it was blowing heat. I'm fine with that.

Now, the fire goes out, and both the room fan and the exhaust fan (two separate fans, of course) stay on 3 or 4 hours. They are still blowing, long after the stove has totally cooled down, and are blowing room-temperature air.

Does the proof-of-fire switch in any way control these fans? My final guess is that the switch is somehow set at a different temp than the old switch I replaced.

The stove is working, and I can live with the fans running, excessively. It just seems kind of pointless to blow room-temp air for hours on end.

 

[johneh]

From the manual:
"Shutting the Unit Off 1. Press the On/Off switch once; the lights will go off and the fire will go out in a few minutes. The board essentially goes into “Safety shutdown”. 1. As long as the temperature within the Stove remains above 110°F the Fans will continue to run. When the P.O.F. switch drops out, the room fan shuts off and the Combustion fan will run for another 10 minutes and finally shut down completely. 2 "

 

[Ssyko]

yep sounds like a new POF disc is needed.

 

[two-if-by-sea]

I wanted to follow up on this. I did purchase a new proof-of-fire switch. I installed it last night, and everything appears to be working correctly again. Must have been something wrong with the other (new) switch I installed. I wish I had swapped that out, before I went and bought a new, expensive control board, but no worries. With the exception of the versa-grate motor, I believe all the guts of the stove have now been replaced.