Hi, I've been having difficulty with my Harman P43. It's my primary heater and I run it on manual, feed setting 4, with the room temperature dial set around 65--75 (I turn it down when I leave the house and up at night once I'm home). I don't use automatic ignition.
Starting about a week ago the stove has been burning out while unattended (over the night or while I'm out of the house). The status light gives a six blink error each time, indicating poor or incomplete combustion. I am not out of fuel in this situation.
I keep the stove clean: The burn pot is scraped until it's smooth and all the holes are unblocked; the big ash pan is emptied regularly; the outside air intake is unobstructed and not frosted over; the combustion blower is clean; the flue is clean and I am careful of the ESP probe when cleaning the flue; the fines box is empty and the little air channel behind the fines box is clear best as I can tell; the fines box cover is replaced and the wing nuts tightened firmly; the "v" shaped part at the top of the interior is clear of ash; the auger is clear of pellet dust. I even took the ESP probe out and gave that a clean too, although it only had a thin layer of soot on it.
I've tried kicking the feed setting up to 5, 6, and then 7 and I still have the same problem. Today I was home and able to monitor the stove. I lit a fire and let it do its thing. It kicked up to full, the flame appeared healthy, and the distribution blower kicked in for an hour or two. When the room got up to temperature, the stove dropped to a low setting and eventually went out, even though it's on manual. At that point it had a six blink error. I quickly checked the air intake clapper, but it was not obstructed. And of course, I was not out of fuel.
I have read some forum posts here of a similar situation and the advice was to replace the ESP sensor. While that may be the case, just yesterday I was holding the sensor in my hands. It's a few years old but it didn't seem damaged. I didn't hit it while cleaning the flue, and I'm really curious how it could be broken. It's just a simple thermocouple with some wires, right? Do they wear out? How often does that happen?
I'm prepared to go buy another one, as at this point I don't see what else it could be, but it does seem weird that it would go bad. It would also be annoying to drop $70 and find it was something else.
Just a few minutes ago, I read that the gaskets can be a problem. I checked the gaskets around the door and around the hopper lid. The hopper lid gaskets were a little dusty, so I cleaned them. The door gasket may be bad: it was quite flat. What's more, is that there have been times in the past where a little bit of windex has dribbled down to the lower gasket and there was one time this past week when the stove burned out but the air intake fan was still blowing where frost had literally formed on the bottom of the door. So the door gasket may have some faults. I'm going to buy a new one and in the meanwhile, I picked at it with needle nosed pliers to fluff it up a bit. This shook out a lot of deposits caked into the rope, and by the time I was done it was pretty fluffy and the door needed a fair bit of pressure to close and lock.
I currently have my toyo set around 75 degrees and the P43 active and set to 65 (manual, feed rate 7). My thinking is that the stove has been failing on its low setting when the room is warm, so I want to try keeping the room warm and see if the P43 can maintain it's low burn for the rest of the day now that I've fluffed the door gasket.
If that doesn't work, I guess the next step is to buy that ESP probe? I was hoping there was something else I'm missing. Thanks for any advice you've got, it would be much appreciated because I am near the end of my rope on this problem.
Edit: I forgot to mention that each time I have gotten the six blink error, the burn pot was empty. That is, there were no partially burned pellets, they all burned up and the stove had shut down.
If your stove doesn't fall under the type I describe in the last part of this post, replace your ESP and
get on with your life. The other conditions that might preempt immediately replacing the ESP is if
you haven't cleaned the stove out well enough and the exhaust pipe (in my case up the chimney) is
fairly restricted... or you have the wrong or sub standard fuel. But the empty bowl (no pellets) suggests
the micro controller (board) software is receiving bad values from the ESP (probe). You just have to
figure out what is causing the ESP to report bad values... defective ESP or problems with the fuel.
While I appreciate the suggestions regarding a leak test using the "dollar bill" and other methods, in
reality most decent stoves do have a bit of leakage and are traditionally set up with code to deal with
those variables. You'd have to have a fairly modest measure of leakage to trip the control loop out of
whack.
Other persons mentioned the ESP doesn't look bad... physical appearance has very little or nothing to
do with it's performance. I still haven't tested one to see if it's a diode, thermocouple or RTD but the nature
of the thermal cycles it makes up to the nominal exhaust temp will eventually wear it out, aka cause it
to fall out of spec. In short, I just assume an ESP in this type of situation has a limited life span, which
I have experienced as a few years of regular cold to full on cyclic operation. A pro-active person will
order and have a extra ESP (probe) around for the eventual replacement.
There's also a mention of the types of fuel causing grief... that might depend a bit more on the design
of a specific stove and the actual program (software) on the stove's micro controller board. I would assume
any reasonable range and quality of pellets would be reasonable, but lower quality pellets will generate a
lot more ash and fines. Our local Tractor Supply has seemingly poor planning and for years would run out
of pellets fairly early in the year. In a fairly deep cold snap, many of us bought and used some of the not
so good Wal Mart pellets and even they work, although they seem almost not worth the effort.
Poor quality and wet/moist pellets can cause grief with the ESP operation. This is where a higher end
stove might have better micro controller software (the program running on the computer board) with the
ability to deal with mixed, sub standard and wet fuel. Although some of the newer stoves do deem to have
an increasingly impressive ability to handle mixed and sub standard fuels... You'll have to figure that out
over time in regards to the specific stove model you have.
Good luck,
cheers,
skipp
skipp025 at yahoo dot com