Very odd Harman issue - lazy fire and consuming more pellets than usual?

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smwilliamson

smwilliamson

The Stove Guy
Dec 28, 2009
4,532
Southcoast, MA
www.pellet-stove-parts-4less.com
Customer was saying that the stove was using nearly 2 bags a day running on a low stove temp setting. I thought perhaps he wasn't doing something right. Then I was thinking he might be burning some real crap. The stove is an an Accentra insert that I installed in 2011. The dudes house is immaculate. The stove is pristine and the pellets he has or rather HAD was Okies. I noticed the cap was also very black.

Right away I'm thinking the thing needs an oak. So we start it up and with all the windows and doors in that room open I can see the flame start to die and whither. Then it comes back! Then it whithers down again. This process plays out the time I'm their and I shut it down. I grab the Harman diagnostic tool and look at the combustion motor voltage...holding steady at 119v.

Hmmm. I got to do something for the guy so I take a stab at it, bad combustion motor. So, we replaced that today. Old motor had a really dark orange tinge around the coil. It definitely was getting hot.

That explains the lazy fire but what kinda blew my mind was that because the ESP is noticing a drop in exhaust temp from the lazy fire, it is compensating with more pellets. With the new motor, 8 hrs has gone by and not even a 1/2 bag has gone through the hopper. Weird Hugh? Makes sense though. For as smart as a Harman is, not knowing its own motor rpm is kinda dumb.
 
Harman's "smart" is accomplished by keeping it simple ;)
 
have you monitored draft when it makes the fire is making those swings? What do you think about the chimney draft overpowering the comb blower? And I know you likely checked this, but the fines cover in the rear of the stove- is it engaged into the top slot? When they aren't engaged, it does really hokey things.......
 
Lousyweather said:
have you monitored draft when it makes the fire is making those swings? What do you think about the chimney draft overpowering the comb blower? And I know you likely checked this, but the fines cover in the rear of the stove- is it engaged into the top slot? When they aren't engaged, it does really hokey things.......
Click to expand...
Naw, it was engaged. The combustion motor was the culprit. Just got an email from the customer, overnight burning normal, back to usual consumption. I did check that though. Sometimes a lego or boxcutter down in the hopper will do these things too.
 
smwilliamson said:
Customer was saying that the stove was using nearly 2 bags a day running on a low stove temp setting. I thought perhaps he wasn't doing something right. Then I was thinking he might be burning some real crap. The stove is an an Accentra insert that I installed in 2011. The dudes house is immaculate. The stove is pristine and the pellets he has or rather HAD was Okies. I noticed the cap was also very black.

Right away I'm thinking the thing needs an oak. So we start it up and with all the windows and doors in that room open I can see the flame start to die and whither. Then it comes back! Then it whithers down again. This process plays out the time I'm their and I shut it down. I grab the Harman diagnostic tool and look at the combustion motor voltage...holding steady at 119v.

Hmmm. I got to do something for the guy so I take a stab at it, bad combustion motor. So, we replaced that today. Old motor had a really dark orange tinge around the coil. It definitely was getting hot.

That explains the lazy fire but what kinda blew my mind was that because the ESP is noticing a drop in exhaust temp from the lazy fire, it is compensating with more pellets. With the new motor, 8 hrs has gone by and not even a 1/2 bag has gone through the hopper. Weird Hugh? Makes sense though. For as smart as a Harman is, not knowing its own motor rpm is kinda dumb.
Click to expand...

Good catch

I would like to put one of those small motor tachometers on the stove's blowers just like the Tach on the car dashboard. Then a nice pointer on the the normal rpm numbers for the each heat setting on non Harman stoves then watch it rev up!
 
Don2222 said:
Good catch

I would like to put one of those small motor tachometers on the stove's blowers just like the Tach on the car dashboard. Then a nice pointer on the the normal rpm numbers for the each heat setting on non Harman stoves then watch it rev up!
Click to expand...

yea, but without an initial reading, its worthless......you know those software thingies available on your puter which tells you the CPU temp, fan speeds and temps, etc.....imagine if all that info were available to us?!!!
 
Don2222 said:
Good catch

I would like to put one of those small motor tachometers on the stove's blowers just like the Tach on the car dashboard. Then a nice pointer on the the normal rpm numbers for the each heat setting on non Harman stoves then watch it rev up!
Click to expand...
Many stove use hall sensors to capture RPMs and adjust voltages to the combustion motor accordingly, Harman is just steady eddy.

Lousy- imagine if a lead manufacturer made an open source stove that could be worked on by anyone. Harman treats its control boards like they are some kind of trade secret, perhaps it is...I dont know
 
SMW, I have never seen a hall sensor on a pellet stove. Can you name the brands that have them? I be curious on their technology tis all.

Ace controllers vary voltage, But don't have any feed back either. A stahling motor can throw curve's. A clipping triac can also be a bugger to diagnose except for the harmonic odd noises the motor will often emite. Having a controller than has feedback and a means to monitor would be a handy detail in diagnostic's.
 
Austroflamm Integra has a hall sensor that monitors the motor speed.
new-1.jpg
 
Hestia, Ecotek,,Bixby all monitor fan speeds. All have the German made fan. Replaceable motor bearings too. Bixby even is computer friendly. To bad owners were greedy jerks.
 
jtakeman said:
SMW, I have never seen a hall sensor on a pellet stove. Can you name the brands that have them? I be curious on their technology tis all.

Ace controllers vary voltage, But don't have any feed back either. A stahling motor can throw curve's. A clipping triac can also be a bugger to diagnose except for the harmonic odd noises the motor will often emite. Having a controller than has feedback and a means to monitor would be a handy detail in diagnostic's.
Click to expand...
Really? They have existed in many European stove since the early 90's
 
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