harman accentra insert - low burn

pellets are lignetics blend. stove starts fine, ignites fine, starts burning fine after 5-10 minutes stove works its way back to approx. 1/3 max burn. started about 1 week ago. temp mode set at 95, feed rate at 6. feed light after ignition is on 40 to 50 sec per min for the 5-10 minutes then tapers back to 20-25 sec per min. Stove mode is even worst as I believe esp works at 300 deg vs 500 deg in temp mode.
exhaust vent cleaned, left and right internal exhaust tubes brushed out
control board replaced
esp probe replaced
combustion blower replaced
vac switch replaced
outside air disconnected
door and hopper gasket dollar bill checked
above checked/replaced one at a time with improvement noted

what have I missed ?

 

Lobo, welcome to the forum.

Our resident "Harmone" expert should be along shortly....... paging Dr. Lousyweather

 

Welcome lobo206
Is the ESP probe changed the same color as the old one? If not, dip switch changed accordingly for it and for newer circuit board?
Do you use a surge protector?

 

Did this problem suddenly appear or has it been going on for awhile?
Does the auger turn freely or is it starting to slow down, it's one part that hasn't been replaced so it may be the culprit( a big maybe)!

 

red esp replaced red esp
dips checked and rechecked
auger motor removed, auger spins freely and pellets feed when feed light is on
problem started in middle of lignetic ton
some thing is preventing the auger motor turning on more frequently
I think I will double check draft after I warm house up a little or sun comes out.

 

That's an interesting situation. You've replaced much of the stove already. I also wonder about the feed system. If you let it run as described, will it continue to run this way indefinitely (slow feed and lower heat) or does it eventually shut itself down with a blinking status code? Almost seems like there is a sensor telling the stove to just back off. My stove will behave as you have described when out of fuel and go into the cool down cycle, but in the end they do shut down with a status code. Have you taken a peek inside the fines box and observed the slide plate operation (requires nearly emptying the hopper) to make sure everything looks clean and moving freely there? Also have to wonder if the ESP probe, despite being replaced already, really is working normally.

 

test mode = all motors run seem to run normal
it runs in the "limp" mode without shutting down
had the slide plate out once and have inspected fines chamber each time I pulled it
if the feed light doesn't come on it can't feed, something is telling it not to energize feed motor. esp (draft related) ? possible feed motor overload function on control board ?

 

As mentioned, check fines box; but the issues sounds like it could simply be a blockage at the bottom of the hopper. Remove all pellets and clean it out. I had the same issue last year and it turned out to be a piece of the plastic bag that was stuck at the bottom.

 

I didn’t read that you specifically did this but have you thoroughly cleaned out the area under the burn pot? My Accentra insert recently shutdown on its own and on restart, the pellets fed into the burn pot but didn’t ignite. I initially thought the igniter failed but as I ran down my prep steps for this season, I couldn’t recall cleaning out the space under the burn pot. I took out the slide plate, used my fingers to remove as much ash as I could, refastened the slide plate and the stove fired right up.

 

you're missing the point, the feed light is not coming on. when the feed light comes on (meaning electricity is sent to the motor) it feeds just fine
there is no blockage. as I stated above I have checked for fines. when the feed motor is given power it feeds fine

 

as stated above it starts fine, ignites fine and burns continuously. I need help with why the feed motor is only feeding (receiving power) 25 % of time vs 90%
repeat no ignitor - ignition problem

 

I saw that you replaced the vac switch. Can you try and jumper the vac switch contacts temporarily to see if the no feed is vac related? Do you try to blow out the small vac hose feeding the switch? I had a similar issue with my P43 and it ended up being dust or fine in the small vac hose. Not enough vac to activate the switch

 

good point, the next time I pull it (its an insert, makes it tuff) i'll check hose, can't check while running

 

looking at schematic since the ignitor runs off the vac switch also and it lights pellets switch initially works. don't know if it could lose vacuum after ignition

 

I get the point. If the board senses a lack of pellets, it won't trigger the auger. A lack of pellets could be just that, low on pellets or a blockage. Still sounds exactly what happened to me on my insert stove. My stove would run fine for 45 minutes, then die out. Just trying to help.

 

Another thing that could make things out of the norm is a control board been spiked, that is why I asked if you have a surge protector for the stove!

 

Because the auger works, albeit at 25%, we can eliminate the hopper lid switch and the vac switch. Lobo, what else is in this circuit? There is a potentiometer for feed rate, right? Although, now that I think about it, the new board probably came with the pots, right? The ESP, room and stove mode pot and the feed rate pot are the only variable inputs the board gets. Somewhere the board is not being told to lengthen the feed rate. Not knowing how the board arrives at this, is there one input that overrides all other inputs?

 

cheapo surge protector. but new board exhibited identical problem immediately after installation, so for now i'm trusting the vendor

 

all your assumptions are correct and are exactly my thought process. I haven't been able to find any info on logic or circuitry of control board. from a cold start the feedrate is more robust in the first 5-10 minutes (start up cycle period ?) and then falls off quickly, both stove mode and temp mode with feed pot and temp pot maxed out. stove was purchased just before the I series came out and only problem was a distribution blower under warranty. so I have 5-6 year history with insert. i'm limping along until I can pull insert again, first sunny afternoon, will double check draft with draft meter and plastic hose to vac switch for slight clog or damage, any other possibilities I come up with.

 

Glad we think alike. I will be following this closely. I know you will solve the issue, it's just a matter of time. My guess it will be a lightbulb moment.