Harmon CB1200 stop feeding pellets after 3 mins.

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tallenjr

Member
Feb 6, 2011
4
PA
I'm having a problem with my CB1200. Had it for about 5 years and thought I figured out all of it's little quirks and issues. I'm pretty religious on my stove and cleanings on it. Just lately it has been having an issue with the fire going out. Well not exactly the fire, but the auger stops feeding...

I know the stove has a heavy feeding cycle to start the burn. The auger works, and drops pellets, call light is on, and the igniter is working (smoke starts to develop in the firepot and out the vent tube). But the auger stops dropping about 3 mins into the cycle, and there is barely enough pellets dropped to create a fire for about a min, then fire goes out and the stove will eventually shut off because it doesn't get hot enough (call light stays on). My question is what causes the auger to stop feeding after about 2-3 mins? But also, EVERYTHING else is working just fine. and by that i mean if i hit the "reset" button about a minute after the stove starts, it drops a bunch more pellets, then the stove runs like normal. It's ran all night like this, perfectly. Until i shut it off, clean it out, and start it back up again, same issue: auger stops feeding after 2 mins, unless you hit reset, and then it works just fine after that.

This is a little bit aggravating because I usually run the stove on a Remote Temp Controller, (which is working fine), but I can no longer trust to run it on a temp mode, i have to have it constantly on for fear of smoke build up if the fire fails during the night. Any help is greatly appreciated. I joined this site YEARS ago, and read up on stuff, but have never encountered this problem on here before. Thanks for any and all help in advance!!
 
Already bypassed, and the call light stays on all the time and never trips out...if snap disk two malfunctions, the call light goes out also, according to the wiring diagram. I'm leaning towards a control box issue, as I've seen to rule out all of the small stuff and not sure what this thing is thinking on the inside. Thanks for the advice though.
 
Have you changed pellet brands recently? If so is the pellet size the same? Sounds like you might have to open the feed just a little more and/or clean or replace your ESP probe. Sounds like the stove isn't sensing enough heat to keep running.
 
Is this a Quadrafire or Harman? CB1200 is Quadrafire...

You've ruled out vacuum switch, thermocouple, thermostat (connection, batteries, line)? Not sure if there are any microswitches on door or hopper ... mine on the hopper is getting weaker.

PS ... Welcome to the forum !
 
I would lean towards the door gaskets leaking. 5 years would put them at replacement IMO based on 1st hand experience with more than half dozen stove makes. Do the dollar bill test on checking the gaskets for being snug. Could temporarily bypass the vac switch to rule out that issue as well.
 
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I didn't see any mention of green LED coming on after fire has started. This is on the control module and i believe it turns green when thermocouple sees the equivalent of 200F. At 800F it turns red.

Check thermocouple ceramic holder to see if its packed with ash or out of position. Could be a bad thermocouple also.

Could also try priming burnpot with a small amount of pellets to see if it starts up ok.

Possible blocked auger chute or needs airflow reduced a bit.
 
Thanks for the replies, but I'm still having no luck. I haven't changed pellets, and I've bypassed snap disks for troubleshooting purposes, I have a solid vacuum on the line, It's almost like the fire start cycle is not completing properly. EVERYTHING is working...just as long as I hit the "Reset" button after the stove turns on and calls for heat. Pellets will drop and feed for about 15 seconds or so ONE time. If I do not hit the reset button, the stove will just burn whats there and never drop anything else. I'm an electrician so i've got a pretty good background with electronics and what not. I just don't know how to confirm it's something specific at this point. Still taking any other opinions. Thanks in advance.
 
Had very similar issues with my CB1200i. Found out it was a broken thermocouple wire. Must have happened when cleaning it one day. The break was hidden behind the shielding. When it heated up after a restart or two the wire was just warm enough to make contact and run the rest of the night. Once cooled down had the same start cycle issues as you. Pull it out and check it real close.
 
I agree that it appears the thermocouple is not sensing the stoves proper heat during startup. Since EVERYTHING is working I don't know what other help we can be. Not to be a wise ass but something isn't working or your stove would be running without having to hit the reset button. I would double check the thermocouple and its placement inside the ceramic cover.
 
Just a quick glance thru the posts, either the thermocouple, or the dreaded CSS? Stove is not hitting temp before time is up for proof of fire and hitting 200*? kap
 
Did you bypass the vacuum switch?
 
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