P43 experiment?

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Nitro-Fish

Burning Hunk
Feb 5, 2009
164
VA
I know this is out there a little, but does anyone know if a P61 burn pot will bolt up to the feeder weldment on a PP38+ (or P43) stove? I'm going to be converting an older PP38+ to at least a P43 auto ignite, (already have all the parts to do this) but was curious to try a P61A pot on it and set the dip switches for a P61A instead of a P43. Maybe another tinkerer has already tried this? No it won't be used in a dwelling, only in a shop.
 

Mt Bob

Minister of Fire
Oct 31, 2013
3,953
park county montana
I would think it would work fine,the gaskets are the same.The only issue I could see is possibly too much heat,I think the fire box is smaller? So you would have to run the feed lower,keep the high flame lower. Don may have done this conversion,give him a call,or PM him.
 
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Nitro-Fish

Burning Hunk
Feb 5, 2009
164
VA
Yes, he likes playing with these things too, maybe he'll see this & respond, otherwise I'll rattle him. I've got a new BP for the P61 that I am going to convert to auto ignite, maybe while I have the PP38+ apart I'll see how the clearances to the glass are compared to the P43 Pot that I got for the P43 auto ignite upgrade.
 
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bogieb

Minister of Fire
Oct 31, 2014
3,093
South Central NH
The interior shape of the pot is different and the P43 has more rows of air holes ( between the two stoves (at least that is the case with my 2012 P43 and 2014 P61a). I don't know the reason. Also, looks like the backs of them are completely different: P43 firepot, P61 firepot. The depth (from mounting to edge of burnpot) have about an inch difference, which may have a negative affect on airflow pattern, ash dumpage etc. Even the part behind and below the firebox doors are different between the two stoves, which is another ash dumpage and airflow consideration.

Even if you were to get them to work the P61a has 3 firebricks as opposed to the P43's 1 firebrick for a reason.
 

Mt Bob

Minister of Fire
Oct 31, 2013
3,953
park county montana
The p38 to 43 is a well known conversion and has been done before. Yes,the upgraded p43 pot is different, but should work,as it replaced the old style in 43's,the gasket seals it.But,the P61 pot is the same,in the mount,as a P38. The pots are wider and longer,for more burn. If the pot is at least 1" from the glass,I think it would be fine,and you would have quite the little heat monster. As far as heat,the 38's were rated to burn 50% corn which burns much hotter than pellets, so it was built for higher heat. But I wouldn't burn corn in it after a conversion.
 
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SciGuy

Feeling the Heat
Aug 17, 2007
363
Constableville, NY
I know this is out there a little, but does anyone know if a P61 burn pot will bolt up to the feeder weldment on a PP38+ (or P43) stove? I'm going to be converting an older PP38+ to at least a P43 auto ignite, (already have all the parts to do this) but was curious to try a P61A pot on it and set the dip switches for a P61A instead of a P43. Maybe another tinkerer has already tried this? No it won't be used in a dwelling, only in a shop.

My feeling is that it would be a bit of a waste. The heat exchange area of a P61 is a good bit larger than a P-38/43 making it easier to pass the heat generated by a larger fire easier to pass into the room with a P-61 rather than a P-38. If you run the stove harder than designed for I'd expect a good deal more very hot exhaust to flow out the vent pipe. PelletHead has the OEM P43 burnpots on sale for $125 right now making that choice hard to resist. I P-43 is build to burn up to ~3 bags per day. If you're not doing that you're not hitting its maximum.

YMMV,

Hugh
 
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Nitro-Fish

Burning Hunk
Feb 5, 2009
164
VA
SciGuy, I understand the capacity of a P43 (in my case a PP38+), however I was looking at the additional 17,500 BTU in a smaller footprint for only the cost of a burn pot and a dip switch setting change. The P61 also has a (albeit minimal) lower feed rate than the P43. I have everything to convert my 20 year old P61 to auto ignite and I also have everything to convert the PP38+ to a P43 auto ignite, so I was batting the idea around to try it if nobody has. If it works, I would just get rid of the P43 burn pot (before use) and purchase another P61A burn pot, so cost would be almost a wash at this stage of the game. As best I can tell, the difference is about 4” in sidewall/front height, I just wasn’t sure about ash box clearance or front glass clearance. I guess it would be considered a “sleeper” pellet stove!

Harman dimensions.JPG
 

SciGuy

Feeling the Heat
Aug 17, 2007
363
Constableville, NY
SciGuy, I understand the capacity of a P43 (in my case a PP38+), however I was looking at the additional 17,500 BTU in a smaller footprint for only the cost of a burn pot and a dip switch setting change. The P61 also has a (albeit minimal) lower feed rate than the P43. I have everything to convert my 20 year old P61 to auto ignite and I also have everything to convert the PP38+ to a P43 auto ignite, so I was batting the idea around to try it if nobody has. If it works, I would just get rid of the P43 burn pot (before use) and purchase another P61A burn pot, so cost would be almost a wash at this stage of the game. As best I can tell, the difference is about 4” in sidewall/front height, I just wasn’t sure about ash box clearance or front glass clearance. I guess it would be considered a “sleeper” pellet stove!

View attachment 289646
You take after the guys I grew up with in the late 60s and early 70s who were always trying to shoehorn a bigger engine in their already hot car;) If you go ahead I'm interested to hear how it works out.

Best of luck,

Hugh
 

rickwai

Minister of Fire
Nov 1, 2011
1,313
ohio
If the current P38 is the old style ( ash pan and front panel are one piece)you have to trim the back of the ash pan a little to clear a P43 pot. The P61 pot would probably require even more trimming.
The P61 is known for a nice tall vibrant flame. With the shorter fire box I think the flame would be up in the heat exchanger all the time. The correct fan blade would need to be installed. The last PC 45 we converted to a P61 we had to retard the charge time way back from factory spec dip switch setttings. We determined the new board charge times are for the newer style Ultra feeders with a smaller throat/slide plate. The old style feeders are larger and feed more fuel per stroke/revolution. I think we cut it back like 75 seconds! On factory settings it would fill the pot and dump fuel into the pan before shutting off. Then from the pot being so full it would get a delayed ignition and light really hard.
Just some food for thought.
 

Nitro-Fish

Burning Hunk
Feb 5, 2009
164
VA
Thanks rickwai, all good info, my PP38+ has separate ash pan, much like my P61 & P68. I have everything to make both my P61 and my PP38+ auto ignite, I was going to do the 38 this weekend, but now they are calling for some nasty weather this weekend, so I’m not wanting to tear into it just yet. The P61 won’t get done until I take it out in the spring once things warm up, that’s why I was batting the idea of trying the P61 burn pot while I was working over the 38.