Another Harman woe about low draft and lazy flames

[eddiewebb]

First time poster after reading dozens and dozens of threads here, so while I appreciate your willingness to help, I'm not looking for general advice, but hoping I can hit some of the Harman owners who have been through this themselves.

For example LeafMold's nearly saved me with this post https://www.hearth.com/talk/threads/might-have-solved-my-p68-burn-problems.32676/ because my does indeed have those (clogged) ports, and a bit of coat hanger and air can cleared out the channels.



The story
I have an older harman xxv (~2003 i think) that burned great when I first moved in, and after ~2 tons is burning sooty, lazy, tall flames, smokey output. The burn pot eventually fills with under-burned buildup, the stuff of klinkers but just filling the burn pot.

Some obvious things I have done, mostly regular maintenance
- full clean, inlet, vent brushed and inspected
- combustion motor removed, cleaned
- full chamber clean (firepot, igniter, ash pan, scraped, banged and vaccuumed

And it really made no difference, virtually none.

Some additional maintenance afterwards
- replaced door gasket (now tightly holds slip of paper)
- replaced ash pan gasket - (what a PITA that was with those darn little screws)

Still garbage fire




Where I am now
Now I have a flame that is _better_, but not good. I can indeed now see almost a vortex where the ports above were cleared out, and it seems to keep the fire aggressive/bright for time after ignition, but then the flame starts to drift down, around, over all over and get lazy again filling the chamber with dull flames and soot.


Draft measures at ~-.38" which seems low (thats what manual reserves as maintenance mode, with full firebeing -.5 -.6)

So I'm thinking I finally need to replace the motor, but wondering if anyone else with a harman had something else. I do appreciate general advice but after spending a few weeks on this forum do think its make/model specific "quirk".


I grabbed some pictures of what low fire looks like just a week after my last full clean, and about ~30 minutes after scarping the pot.

https://photos.google.com/album/AF1QipNf3Fr2Zgzrm17XHypCAGRI5nsEURH2R30dWbAI

 

[johneh]

Eddiewebb welcome to the forum
From Harman manual
PARTIALLY BURNED PELLETS 1. Feed rate too high. 2. Poor air to fuel mixture. (Check burn pot clean-out cover and air intake). 3. Burn pot or heat exchanger tubes may need to be cleaned. 4. Combination of all the above. 5. #6 status blink: A 6 blink control board status indication is caused by poor or incomplete combustion. The circuit board has the ability to track the combustion through feed settings and ESP temperatures. When the control board has calculated poor or incomplete combustion, it will shut down the unit as a safety feature. (Poor or incomplete combustion is a contributor of creosote which may cause a chimney fire) A 6 blink status may be caused by several things: 1. Blocked or partially blocked flue. 2. Blocked or partially blocked inlet air. a. Backdraft damper on the inlet pipe may be stuck closed. b. If outside air is installed, the inlet cover may be blocked. 3. The air chamber under the burn pot may be filled with fines and small bits of ash. 4. The holes in the burn pot may be getting filled with ash or carbon buildup. 5. Combustion blower fan blades may need to be cleaned.
All of they above can lead to what is happening in your stove.
Basically your stove needs to be cleaned from glass ti chimney termination
If you do not have a manual here is one

http://www.noutilitybills.com/PDF/Harman/XXVManual-R7.pdf

 

[ChandlerR]

I had a similar problem with my Accentra 2 FS. Pulled my hair out. I went through everything you did but what I did not know was that I was not cleaning the last bottom row of holes in my burn pot. Not sure if your XXV has the same pot but I would be surprised if it didn't. The row is closest to the auger and is not a full row. It's missing 4 holes on the right side. They were filled with carbon so perfectly that even with my mirror I couldn't see them. Once I located and punched them out, the difference was night and day. I had actually turned my feed down to 3 because of unburned pellets. The other thing that may have contributed to my problem was the wing nut on my fines box was not tight. I pulled the cover and double checked that the gasket was in the right position and not damaged and I made sure the wing nut was tight.

 

[ChandlerR]

One final thing. I had a slightly low draft reading too and the loose fines box cover would explain that.

 

[eddiewebb]

One final thing. I had a slightly low draft reading too and the loose fines box cover would explain that.

Oo, I'll recheck that!

Mine has a gasket that seems to be seating, but it's such an awkward spot I could have missed it.

 

[eddiewebb]

I had a similar problem with my Accentra 2 FS. Pulled my hair out. I went through everything you did but what I did not know was that I was not cleaning the last bottom row of holes in my burn pot. Not sure if your XXV has the same pot but I would be surprised if it didn't. The row is closest to the auger and is not a full row. It's missing 4 holes on the right side. They were filled with carbon so perfectly that even with my mirror I couldn't see them. Once I located and punched them out, the difference was night and day. I had actually turned my feed down to 3 because of unburned pellets. The other thing that may have contributed to my problem was the wing nut on my fines box was not tight. I pulled the cover and double checked that the gasket was in the right position and not damaged and I made sure the wing nut was tight.

I was wondering that but found the OEM parts online and counted the holes, lol.

(broken link removed to https://pellet-stove-parts-4less.com/products/harman-burn-pot-weldment-for-accentra-insert-advance-p43-xxv-1-10-00675)

But your comment about right side makes me wonder since the right side was always a bit lazier, even at good burn.... Does your pot look like the one above?

 

[ChandlerR]

My flame is symmetrical weirdly enough. I'm sure it has something to do with the way the air is drawn through the pot. Here's a picture of mine

 

[articcatbill]

The other thing that may have contributed to my problem was the wing nut on my fines box was not tight. I pulled the cover and double checked that the gasket was in the right position and not damaged and I made sure the wing nut was tight.

x2 on the fine box gasket. I replaced this on a Harman insert earlier this year, I replaced the cover and gasket. The stove has been burning much better since that was replaced. The gasket was really bad and compressed.

 

[eddiewebb]

Update:

New motor & blades raised vacuum from -.38" to the -.6" stated in manual!

FLame is _much_ better, more aggressive, but not bright blue that it was.

x2 on the fine box gasket. I replaced this on a Harman insert earlier this year, I replaced the cover and gasket. The stove has been burning much better since that was replaced. The gasket was really bad and compressed.

Thank you!
I'll give that a shot, I've checked its tightness and never thought to replace the gasket like I have everywhere else though, lol.

 

[eddiewebb]

Grr. Of course my feeder is some obsolete thing not in any manuals. My feeder cover is part 1-10-247217, unlike the new ones it has a single eye right in the center, not a groove in the end.


And google is not my friend finding it anywhere....


As long as I clear the burnpot every few hours I'm getting decent flame. Draft seems good based on vaccuum, so it could be that air is leaking through feeder cover still, but would then it would flow through auger port? Flame is larger in center then edges, so possible, but not sure.

Anyway since I cant find a part I might try to scrape the oldgasket off and just cut some generic high-heatgasket.

 

[tiger]

x2 on the fine box gasket. I replaced this on a Harman insert earlier this year, I replaced the cover and gasket. The stove has been burning much better since that was replaced. The gasket was really bad and compressed.

Interesting, I didn't even notice it's there. Seems to be in decent shape but looked on-line for a replacement, just to be sure. 1-00-677122, $34 and you have to get the metal cover too? Is it available anywhere as just the gasket, without any fabrication?

 

[ChandlerR]

So I have the exact auger drive and fines box cover. My gasket is just a free floating fiber like gasket. I use my fingers and capture it on two sides when installing the cover....which is a royal pain in the butt to get it lined up to the hole for the threaded rod. Once the rod is in the hole I make a final adjustment to the gasket then tighten the wing nut. It sounds like someone glued a gasket on the fines box?

 

[articcatbill]

Interesting, I didn't even notice it's there. Seems to be in decent shape but looked on-line for a replacement, just to be sure. 1-00-677122, $34 and you have to get the metal cover too? Is it available anywhere as just the gasket, without any fabrication?

When we were looking we could only find the cover and gasket together as well. Couldn't just find the gasket. It actually comes with 2 covers and 2 gaskets. The gaskets have a sticky side you remove the film and stick it to the metal cover so the gasket stuck to the cover. Took a little persuading to get the new cover with the new thick gasket in place properly, but it did make for a very good seal.