harman accentra insert - low burn

TLDR, busy time of year, no time.
No feeder light coming on, but it ignites is quite odd. The feeder light really only means that the CB is trying to power the feed motor, not that its actually turning. makes me wonder if its the board. Just for the heck of it, whats the switch 5 position?
What revision is your circuitboard? The newer ones will 2 blink if its the vac switch shutting down the feeder (I think E revision and later?)
If the stove is igniting, but not feeding, its not the vac switch. Were it the vac switch, it wouldn't ignite either....the vac switch controls both the feeder and igniter. Also, if the intake damper were stuck, no draft, same issue...no feed OR ignite. If it were a plugged hose, no feed or ignite....thats not it either.
What it could be......failing fed motor.....tough to diagnose. Sometimes a missing tooth or half tooth on a gear...sometimes catches, sometimes wont.....very tough, because they tend to be intermittent.
Bad gasket you didn't check.....like the hopper/feeder weldment gasket, or the fines cover gasket.
When you cleaned the left tube, did you make sure that you could see the brush come out the other end of the tube where the combustion blower is? make sure to check this....too many folks just create a soot dam when they don't push the brush far enough. The brush will be almost completely swallowed of done correctly
Dont know if you have a liner, but have you checked the cap? They soot up as well.
Have you pulled out the slide plate in the fines chamber? Not CHECKED it, but actually REMOVED it and reinstalled and reengaged it? You could have a fines dam riding on your slide plate throttling down your pellet supply to the auger.
Sometimes it just takes time to fix this stuff, and sometimes, well, a guy or gal just has to actually SEE the unit......not everything can be properly diagnosed and repaired without seeing them....for instance, LOVE to see a draft reading here.
Not a huge fan or replacing a boatload of parts, because other issues can come up in installing them, further muddying the waters, and you're out more money.

 

I think the OP stated that the feed light is coming on just at 25% of the time he believes it used to come on for.

 

as I said, I didnt read the whole thread (TLDR)
Still, draft readings are nice here. We dont actually know what the ESP is reading, DDM read on the ESP could be helpful here as well. Its a given that few folks own a DDM and/or a magnehelic, but as stove technicians, these are a couple of the indispensable tools we use to help diagnose issues. Sometimes there's no way out of getting boots on the ground with the right tools to fix a stove. Well, the other way around it is to keep replacing parts until you fix it, but that gets expensive, as I think the OP was alluding to.

 

had an older analog gauge for draft measurements which showed low draft, obtained newer digital gauge. draft reading about -.035 on high test and about - .03 on low test this is with units set on in/hg which I believe matches the harman manual which says it should be -.45 to-.55 on high; .3 to .35 on low (not - in manual although I assume it should) . aha you say plugged exhaust or intake. I pull the insert partially out rerun with venting now in my belief unobstructed and readings increase to -.04 high -.035 low. readings match analog gauge although I hadn't pulled insert out for "free" vent readings. hadn't thought of that yet. I have an hf60 boiler and had been swapping components except for the control board which is different. insert combustion fan is presently in boiler (operating well, but noisy with slop in bearing on fan side) I picked up new fan ( correct amperage) and will put that in insert in place of boiler fan. am I reading scales wrong ? if I open hopper door while testing draft drops to -.03 high and if I open front door it zeros out. I doubt new fan will fix so it must be gasket issue or air leak some where.

 

ok, your readings confuse me.....I am assuming when you type -.04, etc, you mean -.4, right?
Did you take your readings at the vac switch or at the draft port? Best practice is always to take your readings at the vac switch. Thats the switch which shuts off feed and ignition. You might get a different reading on a port in the firebox, but if your probe/port connection is poor, it introduces error.

Does your unit have the yellow intake nipple in the hopper? Problematic if it does. they plug, disconnect, etc. True, could be a gasket. If it were though, youd constantly have poor draft. If its a gasket, given your draft, its leaking downstream of the combustion fan.

-.3 is kinda low

Have you checked the feeder weldment fines door gasket? Is the screw tight?
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Just some ideas

 

He's measuring in inches of mercury where combustion draft is usually measured in inches of water column.
0.03 in. Hg is about 0.41 in. wc

 

ahhh....makes sense!

 

I caught the scale error after I posted draft readings. i'm checking at port in fire box and using plastic to seal around tubing of gauge. drafts are -.5 to-.55 at high and-.3 to -.35 on low. new board does seem to allow more adj. on low draft. flame is still lazy with low heat. the pellets are lignetics white bag blend. i am starting to think they are the worst pellet I have burned and might be the problem. the feed light (motor receiving power) still is on a reduced level. i'm going to pickup a few bags of something else this weekend to confirm. past experience (somersets.awf soft and hardwood,timber heat, northern hardwood, stove chow, green supreme, newp's, maine woods,natures heat, prestologs, barefoots, rebagged hamers, and probably a half a dozen more. with the harman not allowing any adjustment can't think of another option.

 

I hate blaming pellets, I think its a weak argument, but always a possibility.

Those measurements dont really seem bad. Yea, the new boards allow for about a 25 volt adjustment (I think), rather than just a few volts, which really didnt make a difference in most cases