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

[maglite67]

Give the stove a good cleaning refer to your manual. make sure you remove all the plates and clean behind the combustion fan. The only time you need to change the draft is if you are going up verticaly.

 

[rickwa]

the new stoves have a gasketed connection at the bottom of the hopper instead of the old silicone seal. i thought the new style was suppose to be a improvement?

 

[jtakeman]

Give the stove a good cleaning refer to your manual. make sure you remove all the plates and clean behind the combustion fan. The only time you need to change the draft is if you are going up verticaly.

OP purchased stove used. Draft may have been adjusted for original owners long run or low house current. He may need to re-adjust for his setup.

 

[rickwa]

v ferdman, one more thing that very likely could be causing your problem that i had happen on a stove the other week. take shields off the back if you havent already. turn stove to test mode and check the rpms of the auger motor. it is a 4 rpm motor. if the motor is taking more than 15 seconds to make 1 complete turn the motor is getting weak or the armature needs taken out and cleaned and oiled. i have seen this situation more than once. and it only takes a couple of minutes to do. if the motor is running slow or starting slow it starves the stove for fuel. on a higher burn it is getting enough to mantain a fire but on low it is not enough feed. i forgot this is a gently used unit as opposed to new or i would have suggested this in the beginning. i would put money that this is you problem. you have been through everything else i doubt it is your hopper seal.

 

[vferdman]

v ferdman, one more thing that very likely could be causing your problem that i had happen on a stove the other week. take shields off the back if you havent already. turn stove to test mode and check the rpms of the auger motor. it is a 4 rpm motor. if the motor is taking more than 15 seconds to make 1 complete turn the motor is getting weak or the armature needs taken out and cleaned and oiled. i have seen this situation more than once. and it only takes a couple of minutes to do. if the motor is running slow or starting slow it starves the stove for fuel. on a higher burn it is getting enough to mantain a fire but on low it is not enough feed. i forgot this is a gently used unit as opposed to new or i would have suggested this in the beginning. i would put money that this is you problem. you have been through everything else i doubt it is your hopper seal.

Thanks for that suggestion. I have taken the auger motor out and even taken the armature out. I did not count the RPMs, but it does seem fine. I will do the RPM test next time, but right now it got really cold and the stove is not shutting down since it does not go into low heat mode. I have it set at 66 degrees and it just cranks. Been cranking for two days now without stopping (temps have been in single digits here in New England). So, for now I can't really take the stove out of operation, but when the chance comes up I will definitely check the feed motor for 4 RPM. So, if the motor is weak what do you do to fix it. Replace? I am not sure what "weak" means. Electric motors either work or they don't. There could be a short in the windings somewhere, but that would make the motor intermittent or sensitive to heat, but nothing of the sort happens here. Did you replace your motor?

As far as hopper seal, again I can not take the stove out of service for several days now as it is really cold and it is not shutting down when under high demand. I do see some smoke in the hopper when the pellets are lo in it. Not sure that's a sign of a leaky seal. Not sure what a leaky seal would do to cause the stove to shut down either, but again, I am a newbie at this. It's very frustrating and I am already $50 in hole for the ESP that I don't think needed to be replaced. I am reluctant to replace more parts before I can be sure that it will fix the problem. I also have no idea how to get to the hopper seal. It seem to be pretty deep in the stove and looks like the whole stove needs to be taken apart to get to it. Not a mid-season kind of project.

Thanks again to everyone who is trying to help. I am really looking forward to solving this thing and posting the results.

 

[SmokeyTheBear]

"Electric motors either work or they don’t."

Not quite the way it works. There is after all those nasty things known as bearings, a bearing that is losing lubricant will tend to slow an electric motor down.

It is also possible that increasing voltage (after all that is how these puppies are controlled) will have results in the other direction. Motors are not binary devices.

 

[vferdman]

"Electric motors either work or they don’t."

Not quite the way it works. There is after all those nasty things known as bearings, a bearing that is losing lubricant will tend to slow an electric motor down.

It is also possible that increasing voltage (after all that is how these puppies are controlled) will have results in the other direction. Motors are not binary devices.

You are quite correct, motors are not binary devices. What I meant by saying they either work or not was in electrical sense. If the windings are intact, the motor is electrically sound. Of course, that armature is on bearings. In this particular case there is also a reduction gearbox directly mounted to the armature. In other words the end of the armature has a worm gear on it and goes straight into a gearbox which drives the sprocket.

In any case, it warmed up a bit (we are into low 20's!) before the snow storm and wouldn't you know it, I got a 6 blink shut down again. So, I took the back cover off and fired up the feed motor in test mode. At first I was looking at the auger sprocket and it took about 20 seconds to make one revolution. I had and "aha" moment, but then it occurred to me that the motor sprocket should be doing 4 RPM. Well, I timed it and it's right on the money. 15 seconds per revolution. Motor is quiet and smooth. I took the chain and sprocket off it anyway and removed the armature for inspection. It has two sealed bearings, one at each end and the above-mentioned worm gear. There is plenty of lubricant on the worm gear and the bearings feel nice and smooth. I re-assembled everything, got it all going again and again got a 6 blink shut down an hour later. I now bumped up the temp to 70 and restarted. Just want it to keep going for now.

Any other ideas?

Oh, and if anyone knows hoe to get to the hopper to inspect and possibly repair the seal to the feeder weldment?

Keep those ideas coming. This is a good one. So far nothing has worked. Haven't tried hopper seal repair yet, though.

 

[rickwa]

my next step would to pull the auger. if you are getting smoke in the hopper your auger my be full of creosote or the area where pellets drop down into the auger may be partly clogged. to remove the auger pull sprocket off and loosen 2 bolts that hold auger into housing. from the front take a hammer handle and place it on the end of the auger and tap it out with another hammer. it dont take much to pop it loose.

 

[GVA]

What Exactly do you do after you get the 6 blink?

Do you have to stir the pellets in the hopper or do you just turn stove off then back on?


It's been a while but I don't believe harman has gone to worm gears, but I doubt it's the gearmotor itself when they fail they tend to break teeth and will pause during they cycle till the teeth don't mesh anymore at all.

 

[GVA]

I'll add here since you own a 87 I assume you know what you are doing with it since most non electrical types don't drop a couple hundred on a meter.
Not that this is related but check for a hot / neutral reverse on the receptical the stove is plugged into.
I would suggest that you hook up the meter to a neutral and the NO contact on the Vacuum switch and put the 87 in min/max timed mode and walk away.
You should have 120 on it at all times the combustion blower is running.
Most people here are leaning on something with the draft being off and I agree

 

[vferdman]

I'll add here since you own a 87 I assume you know what you are doing with it since most non electrical types don't drop a couple hundred on a meter.
Not that this is related but check for a hot / neutral reverse on the receptical the stove is plugged into.
I would suggest that you hook up the meter to a neutral and the NO contact on the Vacuum switch and put the 87 in min/max timed mode and walk away.
You should have 120 on it at all times the combustion blower is running.
Most people here are leaning on something with the draft being off and I agree

When the stove shuts down I just unplug it and then plug it back in. If it cooled off enough to go into high draft mode by the time I do that it will burn for a while on high and then when it gets into low draft mode it will eventually shut down. My workaround so far has been to keep the room temperature setting at 70, which tends to keep the stove in high draft mode and keep working (at the expense of extra fuel, of course).

As far as Fluke 87, I am indeed a EE who worked for many years in low level software development (firmware, really). This kind of software development has mostly kept my hardware skills fresh and a DMM, oscilloscope, logic analyzer, etc. were never far away from my desk. Having said that, let me assure you that I did not drop couple of hundred on the 87. I bought it on ebay used for much less than that. However, I appreciate your sentiment that an average homeowner would likely not own a Fluke meter or even know what those are all about. In fact, most people do not know why true RMS can be important (in case of most inverters, for example).

In any case, I think I may have solved the problem. I am just waiting to make sure enough time without shut down passes before I pronounce success.

The last suggestion that I followed was to take out the auger, clean it and re-seal the bearing assembly that keeps ambient air out of the burn pot. Well, I did just that last night. I took the auger out and the tip of it was naturally pretty caked up in carbon. Not terrible, though. The bearing assembly had remnants of some black silicone sealant that I removed and cleaned the metal groove it was in. I did notice in one spot there was discoloration making it outside the bearing. A very small spot, but it seems like it was leaking there just a little bit. I applied blue RTV to the groove and re-assembled the auger. I then noticed a small rubber plug with two wires in it going through the weldment just below and to the right of the auger. That plug carries wires for the igniter. It too had that black silicone stiff around it, but not too much. I removed it, cleaned off old silicone and applied new one and reassembled. Waited an hour to let RTV set up. Fired up the stove and got several shut downs right away. Decided to call it a night and look into it some more in the morning. So, I set the stove to 70, fired it up and left it alone. It burned great through the night on 70, so in the morning I set to 65 and waited for it shut down so I could work on it again. Well, it did not shut down! I set it to 63 and waited some more. It did not shut down! It is still burning on 63-65 setting. I will let it go overnight and if there is no shut down I will call victory. I think the silicone did not set last night yet and was leaking. It set up over night and all is well. So goes my theory. Time will tell.

Thanks to all again for lots of info and good advice. Once this thing is fixed I will post a follow-up.

 

[GVA]

Well since all you do is unplug the stove and plug it back in (you can just turn the knob to off then back on for the 6 blink) it's likley not a bridge in the hopper.
Usually the cure for this is to insert your hand in the hopper and stir the pellets.

I just retired my Fluke 77 after 20 years of use and now use a 12 on the floor and a 87 at my desk.

There are several things that cause the 6 blink
Board
ESP
no pellets
The stove actually is sensing poor combustion.

ESP has been changed
that leaves the board or no pellets......Usually

reason for no pellets

Auger motor is bad
bridge in the hopper
bad combustion blower
bad vacuum switch
plugged exhaust
leak in the system
or any combo of the above

we just need to break down all the above
if you're vac switch opens while the combustion blower is running then
you have a weak draft caused by a failing comb blower, plugged exhaust, leak somewhere in the negative pressure fire box etc.......

It's possible that you did get a bad ESP replacement....Though doubtfull

If it was a small vacuum leak then turning the draft pot all the way down would trip the stove more frequently I would suspect.

I think that you may have a bit more natural draft right now due to the cold temps that have arrived in Mass, (though i've been wrong before)

I think the vac switch IS opening for some reason though.....

 

[rickwa]

good point gva. between the 2 of you, you should be able to come up with a way to hook up a meter on the vac switch and record for a period of time to see if the switch is dropping out. the vac switch is in the neutral circuit going to igniter and auger motor. that would rule out the switch.

V have you tried any different pellets to rule out your fuel source yet?

 

[vferdman]

Well since all you do is unplug the stove and plug it back in (you can just turn the knob to off then back on for the 6 blink) it's likley not a bridge in the hopper.
Usually the cure for this is to insert your hand in the hopper and stir the pellets.

No, there is no pellet bridge. I am aware of that issue and am sure to prevent it as I fill the hopper. I also actually hear the pellets drop into the auger feed.

I just retired my Fluke 77 after 20 years of use and now use a 12 on the floor and a 87 at my desk.

Flukes are the best multimeters I know of. When I was beginning my EE career I worked as a peon at an R&D lab (back in the 80's) and that is all we had. Kind of got used to them there and then when I bought a Sears meter once for home use could not stand it. I waited about 5 years or so for the Sears meter to die and then bought the 87. I love the 87 and expect to bequeath it to my children and grandchildren

There are several things that cause the 6 blink
Board
ESP
no pellets
The stove actually is sensing poor combustion.

ESP has been changed
that leaves the board or no pellets......Usually

reason for no pellets

Auger motor is bad
bridge in the hopper
bad combustion blower
bad vacuum switch
plugged exhaust
leak in the system
or any combo of the above

we just need to break down all the above
if you're vac switch opens while the combustion blower is running then
you have a weak draft caused by a failing comb blower, plugged exhaust, leak somewhere in the negative pressure fire box etc.......

It's possible that you did get a bad ESP replacement....Though doubtfull

If it was a small vacuum leak then turning the draft pot all the way down would trip the stove more frequently I would suspect.

I think that you may have a bit more natural draft right now due to the cold temps that have arrived in Mass, (though i've been wrong before)

I think the vac switch IS opening for some reason though.....

Well, the stove's been running on 65 the whole night now, which is a first since I've owned it. I am keeping it on 65 for now. I did get a 5 blink error last night ebfore I went to bed, which is unsuccessful ignition. I cleaned out the burn pot because it had a lot of hard carbon chunks stuck to sides and bottom probably covering some air holes. Anyway, I am dismissing this 5 blink event for now since I think it is unrelated to the original issue.

It seems sealing the auger assembly has done the trick. I will reserve final judgment for another day or two to eliminate doubt.

Thanks to all once again. It was a very frustrating session, but if it concluded with success then I am good with that. Learning a lot abut these things.

As an aside, can anyone tell me how the inside of the stove is kept under negative pressure? Is it just due to combustion motor? I am thinking the combustion motor takes in as much air as it pushes out, so where is vacuum coming from? Just trying to satisfy the engineer in me.

 

[vferdman]

good point gva. between the 2 of you, you should be able to come up with a way to hook up a meter on the vac switch and record for a period of time to see if the switch is dropping out. the vac switch is in the neutral circuit going to igniter and auger motor. that would rule out the switch.

V have you tried any different pellets to rule out your fuel source yet?

No, did not try different pellets. I am burning what most people in my area burn. I doubt they are a problem or there would be a pretty big stink about it. Anyway, the stove seems to be running without shut-downs now after I removed the auger and re-sealed it. time will tell.

 

[rickwa]

in simple terms on vac question. the air and exhaust is being pulled out of the stove. the air inlet is alittle smaller than the outlet and the air has to travel through the passage ways in the stove which cause restriction, which cause resistance, which causes vacuum. it is a very small amount like .3 inches of water column

 

[vferdman]

in simple terms on vac question. the air and exhaust is being pulled out of the stove. the air inlet is alittle smaller than the outlet and the air has to travel through the passage ways in the stove which cause restriction, which cause resistance, which causes vacuum. it is a very small amount like .3 inches of water column

Got you. Thanks for the explanation. I was just thinking that air in MUST equal air out, so where is the vacuum coming from? restrictions in the air flow the pressure will drop a little. Very little and hence the great sensitivity to minute leaks. If my fox worked (and looks like it did) the leak in the auger bearing assembly was truly minute.

 

[SmokeyTheBear]

in simple terms on vac question. the air and exhaust is being pulled out of the stove. the air inlet is alittle smaller than the outlet and the air has to travel through the passage ways in the stove which cause restriction, which cause resistance, which causes vacuum. it is a very small amount like .3 inches of water column

Got you. Thanks for the explanation. I was just thinking that air in MUST equal air out, so where is the vacuum coming from? restrictions in the air flow the pressure will drop a little. Very little and hence the great sensitivity to minute leaks. If my fox worked (and looks like it did) the leak in the auger bearing assembly was truly minute.

Yes it only takes a little leak to cause trouble and the trouble can come in several forms.

You experienced one, there are others, the biggest one for puffer stoves is additional ash generation, poor ash ejection leading to burn pot overflow and fires in the ash bin or pellet chute and hopper.

 

[vferdman]

in simple terms on vac question. the air and exhaust is being pulled out of the stove. the air inlet is alittle smaller than the outlet and the air has to travel through the passage ways in the stove which cause restriction, which cause resistance, which causes vacuum. it is a very small amount like .3 inches of water column

Got you. Thanks for the explanation. I was just thinking that air in MUST equal air out, so where is the vacuum coming from? restrictions in the air flow the pressure will drop a little. Very little and hence the great sensitivity to minute leaks. If my fox worked (and looks like it did) the leak in the auger bearing assembly was truly minute.

Yes it only takes a little leak to cause trouble and the trouble can come in several forms.

You experienced one, there are others, the biggest one for puffer stoves is additional ash generation, poor ash ejection leading to burn pot overflow and fires in the ash bin or pellet chute and hopper.

Great! Always something to look forward to.