Harmon p68 Airflow Issues?

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drc1912

Member
Oct 23, 2018
19
Seattle
Hi All,

Like always, really appreciate everyone's help answering my (now annual it seems) newbie questions. I have been running this p68 for a few years and for the most part it works great, I clean it regularly and have it serviced once a year or so. Lately i have noticed that the flame frequently isn't "dancing" how it has in the past, and that it seems rather "beaten down". Here is a video of the flame with the door closed, and you can see what happens to it when it opens up. The air vent on the p68 kicks straight back out to outside the house (and has for years, that hasn't changed). I am wondering what could be causing this? Any ideas?

Appreciate any and all help!
Dan
 

Washed-Up

Minister of Fire
Nov 5, 2011
800
Kananaskis,Alberta, Canada
There is a flapper just inside the intake, make sure it’s moving freely in the full range of motion, some put a small magnet underneath to keep them open. Could also be a buildup of carbon around the holes in the burnpot, I use a small pick to keep mine open completely. Definitely looks like a lack of air in the video.
 
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bogieb

Minister of Fire
Oct 31, 2014
2,993
South Central NH
Check to make sure the cover plate to the igniter area is on correctly and is tight.

It does look like an airflow issue, whether it be from lack of air, or a difference in how the air is flowing is the question.
 

jzm2cc

Minister of Fire
Sep 25, 2014
605
Northern Michigan
Also check for obstructions in the inlet and exhaust piping (birds or critters), and ash build up underneath your firepot/igniter area (remove igniter access door and give firepot a few taps with Harman cleaning tool after using fingers to scoop out ash. Surprising how much ash collects on igniter and its cradle.
 

drc1912

Member
Oct 23, 2018
19
Seattle
There is a flapper just inside the intake, make sure it’s moving freely in the full range of motion, some put a small magnet underneath to keep them open. Could also be a buildup of carbon around the holes in the burnpot, I use a small pick to keep mine open completely. Definitely looks like a lack of air in the video.
Do you by any chance have a good picture of diagram of what it looks like/where I could access it?
 

drc1912

Member
Oct 23, 2018
19
Seattle
Also check for obstructions in the inlet and exhaust piping (birds or critters), and ash build up underneath your firepot/igniter area (remove igniter access door and give firepot a few taps with Harman cleaning tool after using fingers to scoop out ash. Surprising how much ash collects on igniter and its cradle.
Appreciate the help! This I have done regularly and it is surprising how it builds up!
 

jzm2cc

Minister of Fire
Sep 25, 2014
605
Northern Michigan
Open glass door, look at front side of burnpot for two bolts with wings, these will be loosen by hand about 1/4 inch and metal plate pulled up to remove. Ash will he inside this area. Helps to remove ash pan and work though this ash door.

20211010_114443.jpg
 

jzm2cc

Minister of Fire
Sep 25, 2014
605
Northern Michigan
Not the best picture representation as the two bolts were already removed along with the igniter access plate, but you get the idea. Note this unit is under repair.
 

drc1912

Member
Oct 23, 2018
19
Seattle
Not the best picture representation as the two bolts were already removed along with the igniter access plate, but you get the idea. Note this unit is under repair.
Really appreciate the help and effort here! I have been removing these nuts and cleaning out this ash area fairly frequently - but is this also the way to check the intake flap mentioned above? That is something I have no idea how to find!
 

Washed-Up

Minister of Fire
Nov 5, 2011
800
Kananaskis,Alberta, Canada
Hopefully it’s far enough from the wall so you can access it, here’s where it is on the P61 I restored

FBE7B338-5DA7-48F5-B156-D5962C5AFCCA.jpeg
 

drc1912

Member
Oct 23, 2018
19
Seattle
Try looking through gaps in rear shrouds, or pull off top panel beneath room probe plug to peek into rear of stove
Thanks so much for the explanation! I was able to remove the shrouds and see that it was open while on (maybe 1/3rd to halfway during operation) and closed while off. To check and see if opening it more while operating would help, I pushed it more open with a wooden stick but it didn’t seem to impact flame.
I also cleaned out the exhaust vent with a stick and vacuum, and it definitely helped with the time-to-light but still having the same flame issues.

I am so appreciative of everyone’s help here. Was hoping I could troubleshoot it myself but I’m just not sure what to try next.
 

drc1912

Member
Oct 23, 2018
19
Seattle
Try changing the door and ashpan door gaskets if they have't been changed. If they're leaking air, that could make for a poor burn.
this is an intriguing idea. the person who serviced our Harmon a month or two ago did change the door gaskets, and it seems like it is slightly less snug than it was previously. That said, I don't fully understand why the flame is better with the door open than closed if air might be leaking in? Currently either opening the top or bottom door both makes the flame more robust.
 

mtnbiker727

Burning Hunk
Mar 11, 2019
185
PA
this is an intriguing idea. the person who serviced our Harmon a month or two ago did change the door gaskets, and it seems like it is slightly less snug than it was previously. That said, I don't fully understand why the flame is better with the door open than closed if air might be leaking in? Currently either opening the top or bottom door both makes the flame more robust.
Do the "dollar bill test." When the stove is cold, open the door and stick a dollar bill where the gasket should touch the stove, and close the door on it. Then pull on the bill and see how much resistance there is. Do this all the way around the door. Last year my door failed the dollar bill test, and someone showed me an old manual that tells you how to adjust the door so it latches tighter. That fixed the problem.
 

drc1912

Member
Oct 23, 2018
19
Seattle
Do the "dollar bill test." When the stove is cold, open the door and stick a dollar bill where the gasket should touch the stove, and close the door on it. Then pull on the bill and see how much resistance there is. Do this all the way around the door. Last year my door failed the dollar bill test, and someone showed me an old manual that tells you how to adjust the door so it latches tighter. That fixed the problem.
I did the dollar bill test, and at most places around the door the bill required a fair amount of force to pull free. At a few places closer to the latch it was able to slide with only a bit of force. Worth working on the door you think?
 

Washed-Up

Minister of Fire
Nov 5, 2011
800
Kananaskis,Alberta, Canada
How does your combustion blower sound? If it’s slightly weaker, the flame will be lazy as well.
 

drc1912

Member
Oct 23, 2018
19
Seattle
it doesn't sounds super loud, but i can see that it is working when I remove the back panel. is there an easy way to adjust?
 

Washed-Up

Minister of Fire
Nov 5, 2011
800
Kananaskis,Alberta, Canada
Just trying to see if it’s weaker sounding to you than previous seasons….still seems to be getting less air than it needs.
Have you changed pellet brands? Just trying to cover all the bases
 

drc1912

Member
Oct 23, 2018
19
Seattle
Just trying to see if it’s weaker sounding to you than previous seasons….still seems to be getting less air than it needs.
Have you changed pellet brands? Just trying to cover all the bases
I think I could be convinced that it sounds weaker than in the past. Is it supposed to always run at the same speed or is it variable (and can I impact it?). Pellet brand has been the same for a few years, so I don't think its that.

I will say that after all the fiddling/cleaning of exhaust areas and running it highest temp/blower/feed settings as possible for a few hours it seems to be doing slightly better, so thank you everyone for the help.

Just a little uncertain on what to do next. I think I might call out a different/new technician to get a second set of eyes on it and see what their feedback is.
 
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Washed-Up

Minister of Fire
Nov 5, 2011
800
Kananaskis,Alberta, Canada
You can try a little 3in1 oil on the combustion blower bearings, the stock ones have a rubbing seal bearing set up and do dry out from time to time. I’ll try to find a pic of the area needing oil
 

Washed-Up

Minister of Fire
Nov 5, 2011
800
Kananaskis,Alberta, Canada
Circled in red where the 3 in 1 should be added, just a few drops should be noticeable

7E835E4E-AE73-4218-8874-D3D0111F9E26.jpeg
 

bogieb

Minister of Fire
Oct 31, 2014
2,993
South Central NH
How about the plate to the fines box? Is that on correctly and snug? If not, that will also disrupt the air flow