Harmon Accenture overheating

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ashes said:
UPDATE- MY bottom convection fan was/is a fasco # B 47120. the old one i took out and the new one i put in are identical in size and model #. HOWEVER, THE SPECS ARE DIFFERENT- specs on old fan read @1500rpm/ 180cfm. new fan specs according to fasco website is 1360rpm/160cfm. less cfm =hotter air,=hotter stove. tech to put new fan in next week.-tbc...
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the room blower vs heat setting or feed rate is not "fixed" in any ratio on a Harman and are thus independent of one another...to a point. If the ESP sees the temps getting up there, it will override the fan control and operate the room blower on high until the ESP temp come sdown, then it will go back to whatever the room blower setting is.

You should look to see if your DIP settings are correct for the stove you have..I think it is 10010000 for an older Accentra the #5 setting should be a 1 if you have a red ESP wire. Anyone else may chime in here if they like. You may have a board programmed to a P61 or P68, you may have an auger motor installed which is greater than 4RPM, you may have a bad ESP, bad board...who knows
 
did anyone change the ESP probe ever? What are the chances it was replaced with a different probe and the dip switch settings werent changed?
 
smwilliamson said:
No, diagnostic computer told you what it was reading, but it doesn't always read correctly up and down the scale.
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Scott is right, the DDM will only tell you what the probe is reading at that particular moment, it will not tell you whether its good or not. We check em on a cold stove, if its cold and reading 400 degrees, its bad. On a running stove, if its reading 100 degrees and we have a big fire, its bad. Also, there are at least 3 different proves available, and while in most cases you can switch probes, some switchouts require a dip switch change, which sometimes doesnt get done, which causes all kindsa haywire.....
 
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Pay attention to what both Scott and Lousyweather are saying. In addition to incorrect probe/control board dip switch combinations a loose prob connection or dirty probe, incorrect auger motor and/or incorrect dip switches for the auger motor/stove model on the control board can cause a stove to over heat.
 
smwilliamson said:
stick a piece of reflective tape on an air fin and use a no contact tachometer to measure RPMS, I'm going to call it as a wiring snafu...It's happened to me and I run into 1 or 2 every other year or so.
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had the harman tech here twice. he call harman twice and was told both times
it was a exhaust blockage problem that the brush was sliding thru. the harman tech did not have access to a scope to check the 2 airway tubes or the chimney pipe. after he left i cleaned everything a 4th time, but it still overheated. today i had my oil furnace serviced and that tech had a 4 ft scope. as a favor ,he inspected the exhaust ports from front to back and from under the exhaust fan towards the front of the stove. there are "no" obstructions in the stove or in the chimney pipe.
lets start from the beginning. this all started in june, after i cleaned the stove and replaced the falco blower (replaced a 2nd time, no help) in order to get at the bottom of the stove i had to disconnect the six wires (thermostat etc) to be able to slide the stove out far enough to get at the fan. these 6 wires were color coded at the male/female connectors and reconnected correctly. today while reading my installation manual , it stated in bold black lettering "if this stove is serviced the green ground wire MUST BE THE LAST WIRE OFF AND THE FIRST WIRE ON" before reconnecting the other 6 wires. specifically remember that when i was done and just before pushing the stove back into place a found the Green wire had fallen off. i just reconnected it, which made it the last wire on instead the first on. the stove was unplugged the entire time so i didn't think it mattered. since i replaced the wires out of sequence and overheating started at that juncture, i feel the two are intertwined. am at a loss as to restore any settings i may have disturbed. note. the service tech swapped out the control board on his 1st visit , but overheating still happened. can hear the exhaust fan running but have no way of telling the rpm's
 
run this back for me....you have an Accentra Insert, it "overheats", you have replaced the distribution/convection blower, it still overheats...is this where we are right now? HOw are you guaging this "overheating"? If you're sticking your hand onto the machine to guage the temp keep in mind that the human body can only tolerate about 140 deg F before your brain just says "ya, thats really hot". Does the unit shut itself down or restrict itself to low burn? when the tech was out to your place, what temps were being given by the ddm at the exhaust point? Is the air coming out the front of the machine generally the same temp across the face or is the air cooler coming from the right hand side? Have you noticed if there is/was uneven buildup of ash material in the combustion chamber? ON the up side, its generally a very reliable machine, and I have yet to see anything that cannot be repaired. Hang in there, there's only so much going on in there...solution to come.
 
The call came in on the Batphone, I'll update you all when I figure this one out. In speaking with him I have a feeling that we are looking at a faulty ESP because it is the only thing which has not been isolated and tested.

How do you test and ESP you ask? Simple, plug in your handy Harman diagnostic, remove the set screw for the ESP and drop in a DDM for measuring temp. They should read the same up and down through the heat range.
 
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smwilliamson said:
The call came in on the Batphone, I'll update you all when I figure this one out. In speaking with him I have a feeling that we are looking at a faulty ESP because it is the only thing which has not been isolated and tested.

How do you test and ESP you ask? Simple, plug in your handy Harman diagnostic, remove the set screw for the ESP and drop in a DDM for measuring temp. They should read the same up and down through the heat range.
Click to expand...

update- you mentioned the auger should stop feeding when the hopper lid is opened. have never seen this happen. fired up the stove and open the lid several times while the auger fed,- no interaction between the two. auger cycled as always. also , i removed the heat shields (right,left and compas) before i started the stove. wanted to see the path of the flying glowing fines. in the past the fines would shoot into the air/exhaust tubes with a decent vilocity. today they appeared lazy (not the flame, just the fines) which would be indicutive of a poor draft. am positive there are no obstructions in the exhaust pipe and there is not any lingering smoke in the firebox. am leaning towards the exhaust fan may not be turning at the proper rpms or the exsistance of some sensor that governs the rpms may be defective. either way i have no skills at this level . will know more after installing a new esp.
 
smwilliamson said:
The call came in on the Batphone, I'll update you all when I figure this one out. In speaking with him I have a feeling that we are looking at a faulty ESP because it is the only thing which has not been isolated and tested.

How do you test and ESP you ask? Simple, plug in your handy Harman diagnostic, remove the set screw for the ESP and drop in a DDM for measuring temp. They should read the same up and down through the heat range.
Click to expand...
hmmm....check out post #4...same thread
 
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Did op ever say how he determined it was over heating? Is the stove shutting down? Did he say he just let it run till the sides got hot then shut it down? I also have the accentra insert & if ran in stove temp mode with setting below 5 the blower motor wont cycle on until the stove reaches a certain temp. I tried this setting once & it seemed that the stove got very hot.
 
jedidiah578 said:
Did op ever say how he determined it was over heating? Is the stove shutting down? Did he say he just let it run till the sides got hot then shut it down? I also have the accentra insert & if ran in stove temp mode with setting below 5 the blower motor wont cycle on until the stove reaches a certain temp. I tried this setting once & it seemed that the stove got very hot.
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determined stove was overheating by touching the sides of the stove, it was the same as touching the glass. have to always shut stove down manually, the auto shut downs never kick in, do not want to melt the paint. overheats in any mode, room temp etc. or feed rate. still cant believe i have the only stove ever made that does this.
 
Have you cleaned the convection air paths? Can you feel an air flow out of the stove?

And your hands really can't be used as a thermometer to gauge a temperature much above 140::F. They will see all temperatures above that as too damn hot as in ouch, man. that is too hot to fool with.
 
SmokeyTheBear said:
Have you cleaned the convection air paths? Can you feel an air flow out of the stove?

And your hands really can't be used as a thermometer to gauge a temperature much above 140::F. They will see all temperatures above that as too damn hot as in ouch, man. that is too hot to fool with.
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under normal conditions i could place my hand anywhere on the stove, except for the glass door. the stove would be warm, but would not burn you as it does now.
had another thought. this started in june and all attemps to cure have been during the warm summer months . my chimney flue pipe is verticle off the back of the stove. it is 36 feet high (12 cleaning rods @ 3ft each). since the external air is heavier in warmer weather the natural venting (heat rise) would be less versus venting in the cold air. am wondering if the change in external temperature would require more blower cfm's to move the air and is exceeding the capacity of my exhaust blower. if so, the exhaust gases would have nowhere to go and cause a temerature backup/increase. also,the capped chimney cover could also act as a partial damper if the cfm capacity is boarderline.

in this dream, this condition could have been previlant all these years but undiscovered since the stove has not been fired up in warmer weather. only way i can debunk this illusion is by asking everyone out there if their flue is equal or more than 36ft? have no idea what my exhaust blower ratings are.
 
What you are now talking about would produce exactly the same situation as a blocked combustion air path, a bad combustion blower, a bad convection blower (is yours actually spinning). a blocked convection air path, or a bad, dirty, or loose esp , or a mis set control board vs esp dip switch setting.
 
all has been ruled out with the exception of " bad esp , or a mis set control board vs esp dip switch setting."
as far as the dip setting, the harman tech switched out the control board with a new one, made no difference. next on the list is new esp and checking the rpm of exhaust blower.
note, all blowers are rotating, smoke in firebox at startup is quickly vented up 4" clean liner pipe, overheating starts about 4-5 minutes later. exhaust blower can be heard spinning while overheating occurs
 
Your convection blower is the one I was wondering about it moves heated air through the stove and into the room. if it isn't turning or the convection air path is blocked the stoves sides will get quite hot as the stove is not having the correct amount of heat removed by the heat exchanger and sent into the room.

There are two complete air pumps in operation with a pellet stove, both must be operating properly to have the stove running normal.

The fire in the stove should reduce in size provided the esp is good, clean, connected, and the dip switches are set correctly as the stove reaches its preset settings.
 
and dont forget, what controls the convection (room air) fan? the ESP
 
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