Circulating Blower kicking in and out numerous times

[Chaser77]

http://www.meyermfg.com/library_manuals/WOODCHUCK__12-21-15_.pdf

Hello again. I have a new woodchuck 526 indoor wood furnace I installed this fall. I had a woodchuck previously so I'm not new to wood furnaces. I am new to using a draft blower, which I finally have figured out after getting some info from this forum. (previous furnace had no draft blower) The last 2 months everything ran fine. I'm having a problem with my Circulating blower now. The Circulating blower is supposed to come on at 160 and shut off at 110. The past 4-5 days it's been acting up. Typically when I'd start a fire, the fire would get hot enough to kick in the Circulating blower and the C blower would keep running until the fire died down a few hours later and cooled the fan limit control to 110 to shut off. Occasionally on a start up, a few minutes after the circulating blower kicked in, the blower would kick off. I'm guessing the circulating air cooled the fan limit control to the 110 degree to trigger it to kick out. This rarely happened, but I did observe it a few times. Over the past 4-5 days when starting a fire, or when the fire starts to get low, the circulating blower is kicking on and off numerous times. It will come on for 5 seconds, then shut off for a minute. Come on for 5-10 seconds, then go off for a minute or so...it probably does this 10-15 times when I'm starting a fire now. Also it has woken me up in the middle of the night for the last 3 nights around 3am when the fire starts to get low...clicks off for a minute then comes on for 5 seconds....then off again for a minute or so..then on for 5-10 seconds. Over a dozen times, maybe more? A few times as I sat in bed and listened, it didn't even stay on for 3 seconds? I don't think the circulating fan, which is set on low, even spun up to full speed before it would shut off? Is it possible the circulating fan is cooling the thermostat in the fan limit control that fast? And if so, why did it just start happening now after working fine for 2 months. Nothing has changed with the system. I called the company and they believe it's just getting cooled down to 110 to trigger it to shut off but they can't explain why it just started doing it after running fine the past 2 months. They said maybe I need a larger cold air return intake? When the fire does get nice and hot after a start up, the circulating fan will stay on and run constantly until the fire gets low a few hours later...then the above on-off cycle starts. Any ideas? Thank you.

 

[garmford]

Have you tried setting your fan limit to a lower temp?

Is your cold air return hooked into the duct system of the house or do you have it drawing off the basement floor?
If you're drawing much cooler are off the basement floor into the furnace you could result in this short cycling but what you're describing still sounds really fast.

The limit switch could just be bad. I'd pressure woodchuck to send you a new one.

 

[Chaser77]

Have you tried setting your fan limit to a lower temp?

Is your cold air return hooked into the duct system of the house or do you have it drawing off the basement floor?
If you're drawing much cooler are off the basement floor into the furnace you could result in this short cycling but what you're describing still sounds really fast.

The limit switch could just be bad. I'd pressure woodchuck to send you a new one.

I have not been connecting to the cold air return. The small utility room the furnace is in is very warm. 80+ degrees most of the time. This was happening when we had the really warm day, not just the recent blast of sub zero temps. And worked fine for two months without being connected to cold air return. I asked about the switch and he said he doubts it is the switch because 90% of the time they fail on meaning the fan would run steady. This evening I just set the temp a little lower. Before I did that I watched the thermostat in the limit control as the system cycled on and off a little bit. It spins a little as it cycles, but it sure isn't moving much..1/4 inch? Not sure how much it should move during normal operation? It actually stayed on for a couple minutes before cycling off this time.

 

[garmford]

This cycling only happens at the beginning and end of the burn cycle? Once the fire is rolling tha fans stays running correct? I assume your limit switch is a Honeywell probe style located behind that blue box on the right side of the unit. I had that style on my Clayton and it worked pretty good but there were times when it would take a while to get going. If I would have kept that unit for another season I probably would have changed it out.
My bet would be a bad switch. You could be the 10%!

 

[Chaser77]

This cycling only happens at the beginning and end of the burn cycle? Once the fire is rolling tha fans stays running correct? I assume your limit switch is a Honeywell probe style located behind that blue box on the right side of the unit. I had that style on my Clayton and it worked pretty good but there were times when it would take a while to get going. If I would have kept that unit for another season I probably would have changed it out.
My bet would be a bad switch. You could be the 10%!

Yep it's a Honeywell like you described. Yes it only happens at the beginning and end of the burn cycle. Had this same type of Honeywell on my previous woodchuck and it never acted like this one does.