To much heat, combustion motor shuts off

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BBAR

New Member
Feb 4, 2010
6
CT
I am new here and new to the pellet world. I bought at Breckwell P-23 in October and burned a ton of Maine's Choice without any problems. I switched over to Spruce Pointe and burned about 3/4 of that ton and the combustion motor started shutting off and I would get smoke in the house because the other motor would keep running, the auger would keep turning and dropping pellets. I found it only did this on level 4. I opened the side of the stove with the combustion motor and cleaned it all out and left the side open. I could run it like that for a while but it did it again. The dealer has been great, he replaced the motor and the control panel, it still did the same thing only it didn't take as long to shut down. The dealer then took the stove to his shop and ran it for a few days and it never shut off. He said it has to be the way I have it piped out of the house that is building up the heat. So here is the way I had it hooked up. Out the back of the stove to a T clean out, 2 feet at about a 45 degree angle to a 90 degree elbow and 2 feet straight out the wall to a cap. When I brought the stove back from the dealer I added a 1 foot section to the rear of the stove before the T clean out, hoping this would help reduce the heat on the motor. It didn't work. I turned it on level 4 and within 15 minutes it shut down. The dealer suggested I go to a 4 inch pipe to get the heat out away from the motor. Does anyone else have any idea what the problem could be? The stove has been thoroughly cleaned and taken apart. Thanks
 
Back pressure or a lack of intake air causes the motor to spin faster and heat up since it can't move enough air and your vent set up doesn't have much in the way of a natural draft. The same thing can happen on a convection blower.

Your addition of more venting just added to the problem.

Is this stove new and how many bags of pellets have you run through the stove and did the cleaning involve removing the combustion blower and cleaning the cavity, etc ...?

The back pressure can also be caused by the stove vent facing into the prevailing wind with an incorrect vent cap.

If that horizontal portion of the run doesn't have a slight vertical rise to it you will get soot pile up that can add to the back pressure situation.

Going to 4" also will relieve the back pressure.
 
Did the dealer run the stove at his shop without any pipe on the exhaust, or did he connect it to an exhaust at his shop? If it ran problem free w/o any pipe, then I agree with Smokey, adding the extra pipe just added to the problem....poor draft with your set-up.

I think you need to go to 4" pipe, and try to get a little upward pitch to the pipe going through the wall as Smokey said.

BTW, are you SURE that the combustion blower has been removed from the stove and cleaned completely, including the vanes?

A pic or pics of your vent configuration (inside & out)will help too.
 
I don't know what your problem is. I do know the stove the stove should not be dropping pellets when the combustion blow stops. It's suppose to be a safety feature, mine has a vacuum switch, when the combustion blower stops the auger stops. Your stove should have a similar setup.
 
slls said:
I don't know what your problem is. I do know the stove the stove should not be dropping pellets when the combustion blow stops. It's suppose to be a safety feature, mine has a vacuum switch, when the combustion blower stops the auger stops. Your stove should have a similar setup.

Multiple failures can and do happen, the vacuum switch needs to be connected, not bypassed, and operational.
 
I agree w/ smokey. priority 1 is to make sure the vac switch isn't bypassed in some way.. then give the vent system a good cleaning/ going over. what about the vent is giving the dealer pause?
 
summit said:
I agree w/ smokey. priority 1 is to make sure the vac switch isn't bypassed in some way.. then give the vent system a good cleaning/ going over. what about the vent is giving the dealer pause?

Combustion blower is thermaling at the OPs house and not at the dealers shop, one of the differences is shop has larger flue than home, ergo the home flue needs to be resized.
 
exhaust temps are too high. exhaust blowers in these stoves have a thermal kickout at 475F if the blower is shutting down either the stove is trapping too much heat in the exhaust blowers area or the temps are way to high. check your manual closely to see if a baffle or cover plate that shouold be installed is missing, also if the unit has an access panel to get to the blower itself , remove it and have a fan standing by to blow air on the exhaust blower motor to cool it down in case of thermal shutdowwn of the blower
 
OK. Thanks for everything so far. I took the combustion motor out and cleaned it, it wasnt really dirty. I may be wrong about the pellets dropping when the blower shut off, it may have just been the remaining pellets in the pot that burned longer than I thought they would. Smokey, what your saying is I need to get more nature draft to move the smoke. I will try going back to my original set up and try to get the pipe straight up and down before it goes out the wall. Out side the wall it just caps off, should I add a verticle piece? the dealer said it was the way the pipes were set up and the heat was not leave the combustion motor. So the problem is the 45 degree angle the pipe is at? When he ran it at his shop he went off the stove with a 1 foot piece to a T clean out, up 1 foot to a 90 degree elbow with 2 feet and then out the wall. The old way I had it set up (stove to T clean out) I could run it on level 4 with the side panel open so the combustion motor could cool better. Thanks again for the help.
 
I should also add that the pipe has been cleaned and the stove has been cleaned thoroughly. I'm not sure what is meant by a baffle? I should also mention the stove is in the basement on the walk out side of the house. The pipe is run through the foundation wall. The foundation is a precast foundation so the exterior concrete is only 2 inches thick.
 
Here is a picture of my stove. You can kind of see the angle the pipe is on.
 

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Could you post a picture of the piping behind the stove?

Do not add anything until we get to see that. It looks like it may be the compound bend right at the exhaust. We need to see behind the stove, too many unnecessary bends is what it is beginning to look like. That adds back pressure. Every T is 5, every 45 is 3, every 90 is 5, every foot of vertical is 0.5 every foot of horizontal is 1 you add all of these up and that is the effective length of your vent system, above so many feet you need 4" pipe. The cut off for going to 4" is usually an EVL of 15. So you see what ever you had for an EVL by adding that 1 foot length at the back you actually increased it. A normal set up for a below grade corner install would be to use a T, a vertical rise, a 90 degree and a horizontal run out the wall. Any of these usually are right on the border line with 3" pipe. The cap on the outside would be an angled down horizontal screened termination cap.
 
Smokey, that was the original set up and I do not have a picture. The pipe went down at that angle 2 feet to a T and then into the back of the stove. So I had 1 T, 2 feet at that angle, the compounded 90 degree and 2 feet of horizontal out the wall to a cap that kind of V'd and blew exhaust out each side. It came with the metalbestos pipe kit.
 
Basically what we are after here is one of two things:

A: An EVL no more than 15 if 3" pipe is used

or

B: An EVL no more than 30 if 4" pipe is used

The cutoff points can vary depending on the stove, your stove may allow a bit more but it isn't likely to be much as it is the weight of air in the stack that has to be over come that counts.

As soot builds up the actual EVL increases so you can take it from there.

Here is my setup and it is very close to the limit for my stove and 3" pipe.

stove T Vertical 4 ' 90 degree Horizontal 2' cap the EVL is 14.

Install is a corner install in the lower floor of what is essentially a ranch with a daylight walkout full basement semi embedded into the top of a hill.
 
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