P68 Questions for the Braintrust - FINES, Bricks, Glass Clean

[davidfieldsnwa]

Team, I have a P68 and it’s working great. A few Questions for the Harman Pellet Stove brain trust.
1. I see it has 3 firebricks behind the flame guide and above the fire pot - there is room for another - any reason I shouldn’t squeeze a 4th in? Any pro or con? What is the role of these bricks? I wipe them off periodically through the season. Ash builds up on the left and right of the three - and it’s a bit awkward to get it out. Just curious mostly.
2. I’d like to understand the role of the fines box. I clean it out periodically because people on this forum suggested I do that and I do see it build up slowly through the burning season,- but I’d like to understand what it is there for. My stove is installed in a corner - so getting to the FB is a bit of a pain - but I’m getting better at getting to the wing nut and little door.
3. I notice that my glass stays clean longer in constant burn than in room temp mode. Why could this be? I don’t have an outside air intake and I direct vent out my wall - pipe is maybe 3 foot total from back of the stove to the tip of the exhaust pipe.

I look forward to your thoughts!

 

[bogieb]

1) This tidbit explains the firebrick purpose much better than I could. I can't see a reason not to install another brick if there is room, but don't know why you would change it from its original configuration either.

2) The fines can clog up the feeder plate if enough are present. I've never had an issue with heavy fines that I know are getting thru to the burn pot (from partially broken down pellets from moisture), The manufacturer recommends cleaning 1x per year but it really depends on the pellets you use. Some have more and some have less.

3) I would assume that the start up contributes to some of the buildup on the glass. My stoves get full of smoke just before ignition. Another factor may be that in room temp, the stove / glass doesn't get as hot. In stove temp, with a constant fire, the glass stays hot. But that is all just a guess.

 

[doneill127]

In regards to the dirty glass. I noticed the same thing. Based on another post I read, I reduced the feed rate from 4 to 2 1/2 in room temp mode and the glass stays clean much longer. My theory is when it’s set at 4, the stove cycles between full on then kicks down to maintenance burn in room temp manual. I believe in maintenance burn the combustion fan kicks,to low and it doesn’t burn as clean. With the feed set at 2 1/2 it spends much more time at a higher burn rate(clean) and much less time in maintenance burn. This only works if I’m trying to maintain the temperature, if I need to heat up from a cooler temperature say from 63 to 68 then I have to dial the feed rate back to 4.

 

[doneill127]

Also noticed I don’t need to clean the burn pot as often. Extended time in maintenance burns tend to build up ash over the burnpot holes , while operating at longer timers at a higher seems to keep the holes open even through the ash buildup

 

[Tonyray]

9yrs burning.P61A... the on/off/ re-ignite of room auto to me is what get;s the glass dirty faster. cloud of new smoke each time it fires up or smoulders right before ignition,, glass not as hot as constant mode[ which for me keeps glass cleaner much much longer..

dont know why 3 bricks but if needed assume harman would have put 4..

many softwoods have lots of fines in the bags and if I keep filling and filling without ever seeing the bottom this could happen.[ this scenario can be wrongly assumed as " pellets stick to the hopper walls and dont slide down when in fact they are just not dropping due to fines block." Not every case but Deffinitly mine..
fines pile up and stops pellets from dropping there by shuting stove off for lack of fuel. Matra softwoods are notorious for lots of fines.
shame because they are super low ash and 8800 btu... 2nd to firs 9K. and yes my fines box will fill up after a while..
my fix now is when half full or less i reach thru pellets to the slide plate and give the pellets a stir and wake up call.

 

[mtnbiker727]

1. The fire bricks direct the flames away from the steel on the back of the stove and up onto the heat exchanger, which is where you want all the heat to go so it can be blown out into the room. I take the bricks all the way out when I clean the stove and brush them off, and the little tray that they sit in. A lot of ash can build up behind them.

2. What the other guys said.

3. Are you using Room Temp Auto, or Room Temp Disabled? There's a big difference between the two functions. If you've never flipped the switch down, you should try it, you might be pleasantly surprised. The stove will maintain the room temperature you set it for, and turn the fan on and off and pellet feed will change based on the call for heat, but the stove will always stay lit. The stove gets hot and stays hot, like a wood stove, but is smarter because it maintains the temperature you set. Contrast that with Stove Temp mode which burns at a constant rate whether it's 60 degrees inside, or 100 degrees inside, the output will stay at that setting on the dial.

In Room Temp with the switch up, it will burn like the dickens on startup, and then slow down and shut off and get cold, then when it calls for more heat it'll burn like the dickens again and slow down and shut off and get cold. I really do NOT like that kind of heat. In this mode you basically have a pellet-fired forced hot air furnace.

 

[Tonyray]

1. The fire bricks direct the flames away from the steel on the back of the stove and up onto the heat exchanger, which is where you want all the heat to go so it can be blown out into the room. I take the bricks all the way out when I clean the stove and brush them off, and the little tray that they sit in. A lot of ash can build up behind them.

2. What the other guys said.

3. Are you using Room Temp Auto, or Room Temp Disabled? There's a big difference between the two functions. If you've never flipped the switch down, you should try it, you might be pleasantly surprised. The stove will maintain the room temperature you set it for, and turn the fan on and off and pellet feed will change based on the call for heat, but the stove will always stay lit. The stove gets hot and stays hot, like a wood stove, but is smarter because it maintains the temperature you set. Contrast that with Stove Temp mode which burns at a constant rate whether it's 60 degrees inside, or 100 degrees inside, the output will stay at that setting on the dial.

In Room Temp with the switch up, it will burn like the dickens on startup, and then slow down and shut off and get cold, then when it calls for more heat it'll burn like the dickens again and slow down and shut off and get cold. I really do NOT like that kind of heat. In this mode you basically have a pellet-fired forced hot air furnace.

Agree about room/manual [switch down] but 1 negative to that.....during all that time in maint mode when blower is off, all or any heat is going out the exhaust pipe.. Not into the room.. not alot but it is going outside....that said, I still will use it during cold nites.. we burn 24/7.

 

[mtnbiker727]

Agree about room/manual [switch down] but 1 negative to that.....during all that time in maint mode when blower is off, all or any heat is going out the exhaust pipe.. Not into the room.. not alot but it is going outside....that said, I still will use it during cold nites.. we burn 24/7.

Yeah, I don't like that part of it. Most days I burn a couple hours in the morning and a couple hours at night. If the highs are going to be in the 20s (which hasn't happened yet this heating season), then I'll leave it on at least over night.
I grew up with a wood stove, which always has lots of heat lost up the chimney, so this is at least somewhat better than that.