Harman Accentra keeps shutting down with the same error code: "Incomplete Combustion"

[cac4]

Ha! I knew I'd be corrected soon enough!

go though the checklist. there's a little plate under the burnpot where the ignitor lives...that has to be cleaned out.

There's also a flapper on that air intake...I wonder if its getting stuck closed, when the stove is running on low, (and not sucking too hard). But when its crankin' along, it stays open. just a thought.

 

[vferdman]

Ha! I knew I'd be corrected soon enough!

go though the checklist. there's a little plate under the burnpot where the ignitor lives...that has to be cleaned out.

There's also a flapper on that air intake...I wonder if its getting stuck closed, when the stove is running on low, (and not sucking too hard). But when its crankin' along, it stays open. just a thought.

I have checked ALL the things in the manual (as was quoted in an earlier post). In fact I've been checking them EVERY time I get 6 blinks, which is every day. I clean the burn pot, the chamber under it, I check the flapper on the inlet, I clean the combustion fan blades, I clean and clean and clean and clean. This stove is probably the cleanest stove in the country right now. The pellets are not too long and they feed great, I can hear them come down and I see a funnel formed in the pellet pile in the hopper. Pellets are 1.5" and shorter. There are no "pencils" in the bag. These are high quality pellets that are well-respected in the area here where many people burn pellets. I tried disconnecting the outside air (I also have one of those fancy Harman thimbles that combines exhaust vent and intake air), I took out the feeder plate and made sure it was working well (it is), I replaced the ESP probe in the exhaust. I am still getting 6 blinks in the morning if I set the temp down to 65. I am at my wit's end. I understand your point about something being broken, but I am running out of options here.

 

[SmokeyTheBear]

I know you are getting frustrated, however did you ever finish tracing out the other end of that vacuum line?

The flapper in the air intake could free itself up before you get a chance to check it at night usually the temperature outside goes down maybe it sticks then and by the time you get to see it it has unstuck.

Since I don't own a Harmon, I'm intrigued by this:

6. Combustion intake assembly not properly latched.

perchance is there a gasket in that assembly that could be bad?

 

[cac4]

I tried disconnecting the outside air (I also have one of those fancy Harman thimbles that combines exhaust vent and intake air), ...

Ok, that fancy harman thimble: this might be out there, but when those things come out of the box, they have a chunk of foam stuck inside them (I assume its for support while shipping) that needs to be removed before running the stove. It has happened that people (professional installers, even) have left them in there. I would disconnect the intake air pipe from the thimble, and check it.

One would still think that the stove would suffocate under all conditions...but who knows? maybe, again, when its "cranking", it can suck through...but not when its down low.

but then...you disconnected the oak altogether, and it still wouldn't run. (??). really really really tight house?

It certainly wouldn't hurt to check.

 

[vferdman]

I know you are getting frustrated, however did you ever finish tracing out the other end of that vacuum line?

The flapper in the air intake could free itself up before you get a chance to check it at night usually the temperature outside goes down maybe it sticks then and by the time you get to see it it has unstuck.

Since I don't own a Harmon, I'm intrigued by this:

6. Combustion intake assembly not properly latched.

perchance is there a gasket in that assembly that could be bad?

I just spent some time playing with the vacuum switch. Absolutely nothing wrong detected. The clear hose comes down to the switch and plugs in to it. I put the feed dial into "Test" mode at which point all the motors come on including the feeder. I then pulled the hose off the switch and heard the feeder motor stop. Reconnecting the house started the motor. Sounds like it's working as it should. Of course, this was with the hot stove after it's been cranking all day. If I get the error code tomorrow I will repeat the test with the cold stove as it sits in error mode.

As for the flapper on the air intake, same deal. Very nice and loose, no signs of sticking. I have pulled the plug on the stove to stop the combustion motor and the flapper came down. I nudged it a few times by hand it was swinging freely back and forth. Plugging the stove in resumed normal operation. Again, this is with a stove in proper working order. I don't see how the flapper can behave any different with the cold stove, though as where it's located it's very cool and is not effected by the stove's heat. In fact, all that cool air being drawn in cools the intake.

As for Combustion intake assembly not properly latched, I honestly don't understand what they mean. There is no latch on the intake. There is metal shroud on the combustion fan that I take out during cleaning to access the fan and the exhaust port from the inside. That has latches and there is no gasket and it would not fit the wrong way. Again, I will examine that part again on the next error condition, but I took it out many times now and always vacuum all around there when I do and m,ake sure everything seats correctly. Will check again.

As for the other end of the vacuum hose, that's the only thing I have not checked except indirectly as described above. I don't know where it goes and so far no one has clued me in. I don't have a service manual for this thing, but again, on next error condition I'll try to trace where it goes. All I can say is it works properly when stove is cranking. I'll try to see where the other end is.

 

[vferdman]

Ok, that fancy harman thimble: this might be out there, but when those things come out of the box, they have a chunk of foam stuck inside them (I assume its for support while shipping) that needs to be removed before running the stove. It has happened that people (professional installers, even) have left them in there. I would disconnect the intake air pipe from the thimble, and check it.

One would still think that the stove would suffocate under all conditions...but who knows? maybe, again, when its "cranking", it can suck through...but not when its down low.

but then...you disconnected the oak altogether, and it still wouldn't run. (??). really really really tight house?

It certainly wouldn't hurt to check.

I was there when the thimble thing went into the wall and I saw the exact piece of foam you are talking about. I specifically asked what that was. I thought maybe a particle filter or something. The installer said it was just packaging and removed it right in front of me. And, yes, I did run the stove with the outside air hose completely disconnected at the stove (as opposed to at the thimble). Good point with the packaging foam. Looked like it may have belonged there.

 

[rickwa]

I know you are getting frustrated, however did you ever finish tracing out the other end of that vacuum line?

The flapper in the air intake could free itself up before you get a chance to check it at night usually the temperature outside goes down maybe it sticks then and by the time you get to see it it has unstuck.

Since I don't own a Harmon, I'm intrigued by this:

6. Combustion intake assembly not properly latched.

perchance is there a gasket in that assembly that could be bad?

this is just a metal assembly that comes off so you can clean the comb fan from inside the stove and you can clean the exhaust tunnel back to the tee from inside the stove with ease. this is a very handy setup and it is similar on all the harmans

 

[SmokeyTheBear]

I know you are getting frustrated, however did you ever finish tracing out the other end of that vacuum line?

The flapper in the air intake could free itself up before you get a chance to check it at night usually the temperature outside goes down maybe it sticks then and by the time you get to see it it has unstuck.

Since I don't own a Harmon, I'm intrigued by this:

6. Combustion intake assembly not properly latched.

perchance is there a gasket in that assembly that could be bad?

this is just a metal assembly that comes off so you can clean the comb fan from inside the stove and you can clean the exhaust tunnel back to the tee from inside the stove with ease. this is a very handy setup and it is similar on all the harmans

Good to know.

I am surprised that there isn't a gasket in such an arrangement considering what it allows access to the exhaust system.

This is where I'm heading just so everyone understands, most of the items in that list are possible air flow issues that might lead to a loss of vacuum shut down. The only thing that baffles me is why when trying to maintain a low setting at night. At that point in time I'd expect incoming combustion air to drop in temperature and the metal it comes in contact with to contract, things like flapping dampers could become stuck inside a constricting tube.

It could be a number of minor things that only become a problem when the bower is running at a lower setting, things such as bad gaskets, loose latches, an out of specification blower, maybe a software setting that isn't correct, etc ...

 

[Lousyweather]

so, it only "6 blinks" when you set the stove to a low temp? (65)? Otherwise, it does not?

 

[vferdman]

so, it only "6 blinks" when you set the stove to a low temp? (65)? Otherwise, it does not?

So far that's been my experience. Just got done dealing with another 6 blink (it's a new morning, after all). Same deal. In fact, I woke up at around 5 am and looked in on the stove and it was working with a lively flame in it. Then at 8 am it had 6 blinks. I took everything apart again and cleaned it yet again. And yet again there was not much to clean. I checked the air intake flapper. It was NOT stuck. There were no unburnt pellets in the pot. There was a lot of ash on the edge of the pot as usual, but other than that nothing looked suspicious in the pot. The vacuum line was fine as when I restart the stove it fires right up. I will try to run it at 65 during the day today and see if I can catch the condition as it happens. I am really at a loos.

 

[SmokeyTheBear]

Can you reduce the draft just a tiny bit?

It looks like the stove may be burning the pellets just a smidge too fast (I think just about every thing else has been ruled out), this could also account for why it goes out especially when the oxygen content of the intake air would be highest (minimum outside temperature time).

This is a setup adjustment and is described on page 12 of the manual. It affects low burn.

 

[vferdman]

Can you reduce the draft just a tiny bit?

It looks like the stove may be burning the pellets just a smidge too fast (I think just about every thing else has been ruled out), this could also account for why it goes out especially when the oxygen content of the intake air would be highest (minimum outside temperature time).

This is a setup adjustment and is described on page 12 of the manual. It affects low burn.

This is interesting. The low draft speed is set to the highest right now. I have no probe described in the manual, but I did turn the adjustment screw to see where it was set and it was at the max setting, i.e. making the fan spin the fastest (on low speed, of course). I did this by ear by turning the adjustment screw and listening to the fan. I put it back where I found it (max speed). I figured it is the best setting in my case since I don't have a way to properly adjust it with the right tool. I assumed more is better, but I am really a noob at the pellet stove stuff, so what do I know. I just got another 6 blink after restarting it at 8 am, so it burned for about an hour or two and shut down with 6 blinks. I purposely left all the temp settings as for the night and bingo! I got a shut-down. I'll go and turn the low draft down and see what happens.

What tricked me is the code is for incomplete combustion. That in my mind can only occur when there is not enough air, but it may be that there is too much air? I am willing to try anything at this point, so turning down the low draft speed it is for the next round...

 

[Delta-T]

what is the position of your feed adjuster knob??

 

[SmokeyTheBear]

Can you reduce the draft just a tiny bit?

It looks like the stove may be burning the pellets just a smidge too fast (I think just about every thing else has been ruled out), this could also account for why it goes out especially when the oxygen content of the intake air would be highest (minimum outside temperature time).

This is a setup adjustment and is described on page 12 of the manual. It affects low burn.

This is interesting. The low draft speed is set to the highest right now. I have no probe described in the manual, but I did turn the adjustment screw to see where it was set and it was at the max setting, i.e. making the fan spin the fastest (on low speed, of course). I did this by ear by turning the adjustment screw and listening to the fan. I put it back where I found it (max speed). I figured it is the best setting in my case since I don't have a way to properly adjust it with the right tool. I assumed more is better, but I am really a noob at the pellet stove stuff, so what do I know. I just got another 6 blink after restarting it at 8 am, so it burned for about an hour or two and shut down with 6 blinks. I purposely left all the temp settings as for the night and bingo! I got a shut-down. I'll go and turn the low draft down and see what happens.

What tricked me is the code is for incomplete combustion. That in my mind can only occur when there is not enough air, but it may be that there is too much air? I am willing to try anything at this point, so turning down the low draft speed it is for the next round...

Actually most error codes issued by pellet stoves are more than a bit miss leading in some cases. Anytime you have more than one possible reason for an error code let alone 7 it is a crap shoot. This is akin to unspecified syntactical error or results are unpredictable.

We still don't know that this is the cause but it is in keeping with what is going on, unfortunately to properly set that you need a magnehelic.

 

[SmokeyTheBear]

what is the position of your feed adjuster knob??

Vladimir, Delta-T is pointing out another means to the same end. I believe that a number of folks run with the feed adjustment fairly wide and let the stove handle it.

On my stove there are three setting for low burn 1-, 1 , 1 +

It is the only adjustment that was designed to compensate for pellet quality at a low burn rate on my stove. I use it as a three level low burn. Some stoves allow burn air adjustments for each selectable burn rate. I'm aware of at least one that has a built in magnehelic and allows full adjustment of feed rate and combustion air.

 

[Lousyweather]

Can you reduce the draft just a tiny bit?

It looks like the stove may be burning the pellets just a smidge too fast (I think just about every thing else has been ruled out), this could also account for why it goes out especially when the oxygen content of the intake air would be highest (minimum outside temperature time).

This is a setup adjustment and is described on page 12 of the manual. It affects low burn.

smokey was alluding to where I was going weith this........without a magnehelic, its cant be quantifiably set, but you might reduce that setting somewhat......counterclockwise a bit.....

 

[vferdman]

Can you reduce the draft just a tiny bit?

It looks like the stove may be burning the pellets just a smidge too fast (I think just about every thing else has been ruled out), this could also account for why it goes out especially when the oxygen content of the intake air would be highest (minimum outside temperature time).

This is a setup adjustment and is described on page 12 of the manual. It affects low burn.

smokey was alluding to where I was going weith this........without a magnehelic, its cant be quantifiably set, but you might reduce that setting somewhat......counterclockwise a bit.....

Well, from page 12 of the manual:

If the unit is not adjusted properly, it does not cause a safety concern. If the unit is adjusted too high, only efficiency is lost. If the unit is adjusted too low, the low draft pressure switch will not allow the feeder motor or the igniter to operate.

This leads me to believe that setting the low speed to maximum is harmless (at the cost of some efficiency), while setting it to minimum may cause stove shut down. Am I missing something? Anyway, I did adjust it down, so let's see what happens.

My feeder adjustment is at 5. I have moved it there from 4, but the behavior is the same. From what I understand the feeder adjustment is the time limit for the auger motor to operate at one time. In other words, on 4 it may only go on for 4o seconds at a time max, but can go on for shorter periods of time if the controller decides so. So, I am not sure if bumping it up may help. I will keep it in mind and will certainly try it as one other remedy. This actually makes a bit more sense since the incomplete combustion can only occur if there is not enough fuel or not enough air. Let's see where we are with a lower setting on the low draft speed. Don't want to change more than one thing at a time.

 

[cac4]

Can you check the voltage at the outlet where the stove is plugged in? the factory sets the "draft" to be correct for a certain voltage (can't remember what that is, exactly), and that can vary quite a bit from house to house. I seem to remember people saying that the draft seldom needs to be changed from its factory default setting, if the voltage is near or at 120. I recall checking mine w/ a voltmeter, and it was like 121v, so I didn't touch the draft. (installed it myself, and I don't have a magnahelic, ).

 

[vferdman]

Can you check the voltage at the outlet where the stove is plugged in? the factory sets the "draft" to be correct for a certain voltage (can't remember what that is, exactly), and that can vary quite a bit from house to house. I seem to remember people saying that the draft seldom needs to be changed from its factory default setting, if the voltage is near or at 120. I recall checking mine w/ a voltmeter, and it was like 121v, so I didn't touch the draft. (installed it myself, and I don't have a magnahelic, ).

I get 123.7 Volts from the outlet where the stove is plugged into. This is measured with a Fluke 87 True RMS meter, which can be important. The lesser meters will read slightly off if the waveform of your current is anything less than a perfect sinusoid. Anyway, 123.7 is close enough to 120, I reckon.

Also, see the quote from page 12 of the user manual I provided in an earlier post about the voltage adjustments for the combustion motor. Basically, setting it to max should, in theory, guarantee no shut-down (albeit at the expense of more fuel usage). I had it set to max as it turns out and that would indeed be a reasonable factory setting.

 

[Delta-T]

any chance the slide plate in the feeder mechanism is in upside down? the plate has a flat side and a side with a ridge. The ridge side should be facing up. if its facing down it can lead to too few pellets being fed.

 

[SmokeyTheBear]

Can you check the voltage at the outlet where the stove is plugged in? the factory sets the "draft" to be correct for a certain voltage (can't remember what that is, exactly), and that can vary quite a bit from house to house. I seem to remember people saying that the draft seldom needs to be changed from its factory default setting, if the voltage is near or at 120. I recall checking mine w/ a voltmeter, and it was like 121v, so I didn't touch the draft. (installed it myself, and I don't have a magnahelic, ).

I get 123.7 Volts from the outlet where the stove is plugged into. This is measured with a Fluke 87 True RMS meter, which can be important. The lesser meters will read slightly off if the waveform of your current is anything less than a perfect sinusoid. Anyway, 123.7 is close enough to 120, I reckon.

Also, see the quote from page 12 of the user manual I provided in an earlier post about the voltage adjustments for the combustion motor. Basically, setting it to max should, in theory, guarantee no shut-down (albeit at the expense of more fuel usage). I had it set to max as it turns out and that would indeed be a reasonable factory setting.

Setting it to max will only provide more combustion air, which can cause the pellets to burn faster thus emptying the burn pot leading to possible loss of fire. Which while not a safety issue is a burn issue.

The manual is quite clear in that this adjustment is likely not to be correct as comes from the factory, nor is it likely to be correct if the stove gets moved to a different location.

 

[vferdman]

any chance the slide plate in the feeder mechanism is in upside down? the plate has a flat side and a side with a ridge. The ridge side should be facing up. if its facing down it can lead to too few pellets being fed.

The slide plate is in correctly. I took apart the feeder mechanism and cleaned all the parts I could get to. Nothing was wrong. The plate would not go in with the ridge down (I tried), so I am 100% certain it is in with the flat side down. Anyway, my full throttle operation is fine and pellets are coming down good and plenty. Only low temp operation seems to be a problem.

 

[Lousyweather]

ok, Vlad, prepare to have your problem corrected........dont pish-posh this before you try it.......

get some RTV, empty the hopper, and seal where the hopper meets the feeder weldment......dont use the stove for a day or so, since you'll have wet RTV at the base, causing pellet jambs......seen a few leaky hoppers do what you describe.....also, while youre at it, check the lid seal, but i think you've already done that. I think its a leak at the base of the hopper......

 

[vferdman]

ok, Vlad, prepare to have your problem corrected........dont pish-posh this before you try it.......

get some RTV, empty the hopper, and seal where the hopper meets the feeder weldment......dont use the stove for a day or so, since you'll have wet RTV at the base, causing pellet jambs......seen a few leaky hoppers do what you describe.....also, while youre at it, check the lid seal, but i think you've already done that. I think its a leak at the base of the hopper......

Well, since nothing else is working I think I will consider your suggestion. The hopper is nearly empty now. I had no fewer than 3 6 blink conditions today. I left the temp set at 65 all day to try and catch it, but never actually saw it go into the error mode. I would just look in on it now and then. Anyway, I also thought about an intermittent connection at the PCB. The wire from the ESP is very long and was coiled up inside the stove. It then goes up into the control box and terminates in a molex connector. I did not check that part of wiring, but the new ESP came with splices so as to leave the original black wire in place, cut the old ESP off and splice in the new one. The splice connectors are very cool type where you do not need to strip the wire, just insert the wires in and squeeze with pliers. So, I am thinking if there is a bad connection at the board I did not fix it with the new ESP. What troubles me about your theory of leaky hopper is that after the 6 blink condition is set I can restart the stove by unplugging and re-plugging it and it restarts and goes on for another significant period of time. This does not negate your theory, but still... Do these hoppers just sit on the weldment? Is there a gasket there? I have not looked at how the hopper mates to the weldment. Also, the installer looked and the hopper and said it is not one of those "problem" stoves that have a ring of discoloration on the hopper from smoke because of leaks. Anyway, I will definitely look into it. Especially if you give me more details on how to get to the place I want to RTV. Should RTV be high temp? I assume so.

 

[jtakeman]

There is a draft adjustment on the control board. Have you tried playing with it? Maybe set to high.
EDIT:
Sorry, I think its what SmokeyTheBear is talking about.