Harman P68 low burn and Low heat out put ???

[northeast puller]

I have a Harman P 68 in my basement that rocks and does the job nicely. I scored a used Harmon P 68 3 years old with the hearth pad piping and extended hopper add on for $1500 on Craig’s list. I put it in my hardware store.
Well it does not burn like my other one at all. It is a low bun in the pot and not a lot of heat being pushed out. Before installing it I gave it a good cleaning in the garage. Including the igniter box. So I know it is clean. The pipe I put in is brand new Sequrk (sp). The install is like this out of the stove to a T then up 2 feet to a 90 then out thrue the wall thimble 3 feet to a horizontal term cap. All joints have High temp RTV plus tape. I then added the out side air kit thinking this newer building is tighter and maybe was not getting enough air. I hooked up a T stat to it and it and the stove setting are set like my other P 68 that rocks Both stoves and even My Classic bay which also rocks when need are burning the same Ligneitcs pellets. They may be different lot numbers. But I am not trying to burn crappy pellets. I have changed stove settings and double checked every thing twice. When cleaning I was very careful not to whack the probe in the exhaust tunnel. So what gives? Am I missing sum little detail. I would rather not call the service teck to come out and show me some little stupid thing that I may have over looked. Any suggestions before I make the call?

Thanks North east puller

 

[P38X2]

Did you try it without a tstat? Tried it on "stove temp" on high, blower on high? Hopper and door gasket good? Fines box cover on properly and tightened securely?

 

[northeast puller]

Did you try it without a tstat? Tried it on "stove temp" on high, blower on high? Hopper and door gasket good? Fines box cover on properly and tightened securely?

Yes I have tried it with out the T stat I checked both hoper gaskets they are good. I have run it with the regular hopper and then the extended hopper no changes in out put. It just has twice as many pellets in it. I have tried every stove setting that I could. I was going to check the fines door. But a customer came in the store and then for got to check it thanks for reminding me. I will check that in the morning. It almost seem like it is starving for air. But the Glass is clean there are no unburned pellets left over and the firer is short real short but not yellow and lazy.

North East Puller

 

[Bioburner]

Possible room temp probe problem but that should not affect it in stove temp mode. Could well be the esp giving the grief as it controls convection fan too.

 

[Rushed]

Did you ever find out what your problem was.
My P68 is doing the same thing.
I changed my combustion blower motor over the summer.
The stove seems like it's starving for air and it soots up with dark ashes that fill the burn pot.
I cleaned the stove & vent pipes.
????????