Harman P68 burnpot deteriorating.. again
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I wonder if the Low Draft Voltage Adjustment can compensate for the higher pressure that may be caused by my adapter? .. I don't fully understand what this adjustment does, but the manual does say, "If the unit is not [low draft voltage] adjusted properly, it does not cause a safety concern."
What makes this whole thing so difficult is that there will be no visible and immediate confirmation of any "fix," since the burnpot deterioration occurs over the span of a few years. If I choose to remove the OAK entirely or use a larger inlet pipe (and remove my adapter), it will be at least two or more years before I know the outcome. Frustrating.
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Great! Thanks for the info.. will look into getting one. .. Are the fittings you posted above everything I will need to attach it to the stove? .. I see there is an access bolt on the left rear corner of the stove firebox. .. And what's the T fitting for? It's not just gauge -> hose -> stove?
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I believe so. I teed into the connection on the draft pressure switch. My stove is an accentra. Hope it’s not too much detail, but combustion fan is a volumetric device. At high elevations, the air density drops so not as much air is being moved by the fan. So fire burns lean and less air to cool the metal of the burnpot. Add the restrictions on the oak and it might causing the issues.
Mt Bob
Minister of Fire
I'll stick with leaving carbon on the pot,off season. Heck, you only burn 2t a year! Think of it as a layer of rust, trapping moisture, ruining a layer of metal. You should just unhook the outside air in summer,also. At that altitude, you have cool/cold nights, and air will be moving in a loop, especially with stove being inside. Unhook tube, stuff a rag in it, leave stove connection open.
No, it is not your intake air reducer. It is not a water hose, it is on the suction side. If you restrict the suction side, less air gets to the fan blades. For all of you that doubt me, slide your hand across the air opening,restricting it, when stove is running, watch your flames, watch your meter, if hooked up, see what happens.
No, it is not your intake air reducer. It is not a water hose, it is on the suction side. If you restrict the suction side, less air gets to the fan blades. For all of you that doubt me, slide your hand across the air opening,restricting it, when stove is running, watch your flames, watch your meter, if hooked up, see what happens.
I would doubt that you will see much difference in vac with the inlet fitting In or out. Put the sove in start up withe the rear guard off And vac guage hooked up. Then take the fitting loose from the stove and see if the needle moves. The low draft adjustment only comes into play when the stove is at an idle.
Here’s a copy of pellet stove training program I found online a while ago. Draft testing procedure and high low numbers start on slide 20. Good luck
Have you confirmed that your ignitor is not staying on? This is a common failure, and when it happens it can be hard to detect (without an energy meter or keen eye on your power bill). When the ignitor stays on, the pot will split about where yours is bulging. This happened to me. After the fire is out, but the combustion fan is still on, feel around where the bulge is... if it's hot, your ignitor is staying on whenever your stove is on. Ignore the LED, it may go out but the ignitor can still stay on!
Mt Bob
Minister of Fire
"Forge effect"? Not sure of what you speak.
'The same heat but in a longer time" is not "the same heat" Heat is rated by output per time. 30k btu over 5 hours is not the same as 40k btu over 4 hours, you are liable to have a clod drafty house.
Harman's do not have the adjustments you mention, the burning "ratio's" are controlled by the programming of the control board and the exhaust sensor, and design of the stove.
look at the photo, it is ancient and perhaps current for some, system for softening iron. blow under the coals / pellets how about these stoves, produces a gigantic heat, it's not just flame. If you can't reduce btu, I don't think you will solve it
Mt Bob
Minister of Fire
"Forge Effect"= made up term. Whatever, yes I know about forges, have made a few knives., and comparing a stove to a forge is just wrong. I suspect you are new to pellet stoves. Anyway, have a good day.
ok today you didn't agree with me, will you follow, in Italy there has been talk of this thing for years, too much air, forge effect, or whatever you call it and burnpot warped, worn out, good day to you too
tlc1976
Minister of Fire
Beat me to it while I was typing, I figured it was a term more familiar to you being in Italy. And you probably being more familiar with simpler stoves.
I don’t have a Harman either, but it appears they run more like an automatic climate control, where you choose the output, and it does what it needs to accomplish that. So if you want to get the house temp up from stone cold, it will run full bore to get there. From what I understand anyway.
Where as with a simpler stove, you choose the input, and adjust it if you’re not satisfied with the output. If you want to take it easy on the stove, or use a set amount of pellets, or whatever, it’s up to you. I like to start mine 2-3 hours before I get home, on the lowest setting, and by the time I get home the heat has spread through the house pretty well and I’m comfortable. As opposed to coming home to a cold house and running it full blast, and by the time the heat has travelled through the house I’ve used more pellets overall and worked the stove harder too.
Of course the Harman is designed to run hard, but the burn pot is a wear item too. If it could be run based on heat settings rather than temperature settings, then it might make the burn pot last longer. Maybe it can, I don’t know.
That is if that’s what’s causing the damage in the first place.
I probably wouldn't even reduce btu, perhaps I would put an additional plate that protects the burnpot
I’m a little late to the party here but I’ve replaced 2 burn pots in my P68 over 12 years with the same issue. I do scrape the burnpot regularly and put a plastic box of damp rid (or equivalent) on the pot every spring when I’m done with the stove and replace it every 3-4 weeks during the summer. I also clean it thoroughly every summer and scrape it once or twice a week during the season. The first time it happened with the stock burnpot, I replaced it with a Harman burnpot..it lasted 4 years until the same issue happened. I then decided to replace it with a burnpot that wasn’t manufactured by Harman (admittedly, it was cheaper and I figured if I was going to replace them every 3-4 years then I might as well save some money at the outset). Anyway, knock on wood, I’m at 5 years with that burnpot and no issues. The other thing is that when both burnpots went, I was using Hamer Hot Ones pellets. Not saying there’s a correlation there but I haven’t used the Hamers since and haven’t had an issue.
Hello
I do not like outside air kits that bring damp air in. This is especially worse if you live in a damp climate near the ocean of in New England or the upper West Coast. Therefore for these areas I highly recommend Selkirk DT venting that brings the outside air in thru the venting down along the outside of the hot flue pipe. This dries and warms the outside air before it goes into the burnpot!! I have 3 Harmans, 2 - P61s and a Harman Advance. I use it on all 3 and it also improves the efficiency by 10 percent.
If the ash in your Harman when cleaning is clumpy or heavier then it is has moisture in it! Not good for any pellet stove. Yes this Selkirk DT venting setup is more expensive but does pay back with light fluffy ash for easier cleaning and the 10 percent boost in efficiency! I have installed many of these and all with very good results!!
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