Combustion fan will not turn off on St. Croix York insert pellet stove

[dhickok11]

Hello, I'm brand new to the forum, this is a great resource for a new pellet stove owner, thanks in advance for all your contributions and advice.
I purchased a used 2006 St Croix York insert on craigslist early this winter, and it was running great, until one day, while running a fuse blew.
I changed the fuse and it blew again as soon as I plugged it in. I disconnected all the motors and put another new fuse in, I plugged them back in one at a time, unplugging in between connections. The fuse did not blow again after making all the connections, but shortly after the combustion fan would not turn off (I'm not sure if the problem started immediately after this incident or soon after). So, as soon as I plug in the unit, without even turning unit on, the combustion fan turns on, whereas before the fan would not turn until the stove was actually powered on. I use the stove in manual mode only, as there is no thermostat attached. Long after the stove cools down and the convection fan turns off, the combustion fan keeps running and does not shut off without unplugging unit. I have developed a pretty good understanding on how my stove works, but I have been through the manual, and I am not sure what actually controls the combustion fan powering on and off. The stove has been running great otherwise, but allowing the unit to cool down and then unplugging every night is such a hassle. I would appreciate any help in this matter.

Thanks,
Dan

 

[UncleAnthony]

I don't know your stove, but guess it may be control board. have you the schematics ?

 

[Don2222]

Hello

Before I would blame the control board, I would check out the Low Limit switch 1st! This would be a cheap fix.

See my detailed explanation with pics. If the Low Limit switch does not open when the stove cools the combustion fan will keep running!

https://www.hearth.com/econtent/index.php/forums/viewthread/87801/

Hope this helps.

 

[UncleAnthony]

Thanks, thats great to check the low limit switch. I could not open the maint manual, so it was a guess.

 

[heat seeker]

Don got it. You can just pull one wire off the switch as a test. On my Afton Bay, there is only 5VDC, but yours may have a dangerous voltage.

I run my fans while cleaning the stove by jumping the Proof of Fire switch (low limit) with a small toggle switch, so I know that if that POF switch is bad, the blowers (both) will run.

Can be had from Grainger for about $15, but you'll have to bend the ears and use longer screws to hold the switch on (at least on my Afton Bay).

 

[Don2222]

Hello

You do not have to pay even $15.00 if you buy the White Rogers at pex supply. (Most are made by White Rodgers anyways!)

See link and pic below of a compatible low limit or another term “Proof of Fire†Switch POF
$5.65 These plastic ones are made by White Rogers
http://www.pexsupply.com/White-Rodg...50-Degrees-F-Cut-Out-130-Degrees-F-14695000-p

 

[Don2222]

Don got it. You can just pull one wire off the switch as a test. On my Afton Bay, there is only 5VDC, but yours may have a dangerous voltage.

I run my fans while cleaning the stove by jumping the Proof of Fire switch (low limit) with a small toggle switch, so I know that if that POF switch is bad, the blowers (both) will run.

Can be had from Grainger for about $15, but you'll have to bend the ears and use longer screws to hold the switch on (at least on my Afton Bay).

I like the idea of the toggle switch to turn the blower on while cleaning!!

Great idea!!

 

[heat seeker]

Thanks!
I do believe the POF on my Afton is [close @ 110ºF, open @ 90ºF].
It seems to take forever to cool to the 90º, and the stove is cool enough to clean long before that, so I'm adding another switch in series to shut down the fan for cleaning. If I should forget to turn the switch back on, the stove just won't start (#2 light), so no harm done.

 

[dhickok11]

Thanks for all of your input. What confuses me is the POF switch is what controls the convection fan turning on and off, and the convection fan seems to turn on and off at the correct times, obviously I don't know that the actual temperature is necessarily accurate, but it seems to operate perfectly. And the convection fan shuts down as the stove cools down, it is only the combustion fan that stays on. So if this switch were bad, wouldn't it affect the convection fan as well?
Unless there is a separate switch for the convection fan?

 

[heat seeker]

Same switch for both. You may have a shorted triac on the board, which can be replaced if you're handy with a soldering iron.

 

[heat seeker]

Dupe post - sorry.

 

[Don2222]

Thanks for all of your input. What confuses me is the POF switch is what controls the convection fan turning on and off, and the convection fan seems to turn on and off at the correct times, obviously I don't know that the actual temperature is necessarily accurate, but it seems to operate perfectly. And the convection fan shuts down as the stove cools down, it is only the combustion fan that stays on. So if this switch were bad, wouldn't it affect the convection fan as well?
Unless there is a separate switch for the convection fan?

The switch we are refering to is located on the exhaust plenum right near the exhaust fan. Is that the switch you tested?

Usually it is open when cooled and a closed circuit when heated above 140 degrees.

 

[heat seeker]

What concerns me is that both blowers are not on all the time. If my POF switch is made (or jumped) both blowers come on and stay on. One blower only staying on all the time concerns me.

Normally, when the stove is turned on, both blowers come on for about 30 seconds. If the vacuum switch is satisfied, the room blower shuts off until the POF is made, then turns back on at the selected speed.

It sounds to me that whatever ate the fuses damaged the combustion blower triac - shorting it "on".