Harman Invicible T burn/flame/smoke issue

[Pitou]

Hello,

I'm having an issue with my stove and not sure where to look. All parts are fine, the motors run, but the pellets don't burn well. When I inject air from the right side in the little square hole, flame is better but it doesn't last. I did clean everything I could but I'm not sure of all the hole and conduits in this stove.

Any clue?

Thank you.
Pitou!

 

[Washed-Up]

Check your burnpot holes to make sure they aren’t carboned up, have you tried different pellets? Worse case would be that the combustion motor needs to be replaced

 

[Pitou]

I'll double check the holes but they seemed fine. The combustion motor, ESP probe, control board are all brand new.
I check the chimney and it's fine. No obstruction and smoke get out well. I tried 6 differents brands of pellet.
Sometimes I get a big "swoosh" from the inside like to much pressure and smoke from the door and some holes. It's a bit scary!

The only place I didn't really look in inside the burn pot up to the rear because I don't know how to access it.
Thanks!
Pitou!

 

[johneh]

How tight is your home?
try opening a window just a little
does that improve the fire
Do you have an OAK installed?

 

[Pitou]

it's a split level, very wide. It did work fine for many years. It started acting up last year and didn't retry until now

 

[johneh]

When I inject air from the right side in the little square hole, flame is better but it doesn't last.

Indicates a lack of combustion air !
which says to me a dirty stove. Ash plug somewhere,
a hidden ash trap?

 

[Washed-Up]

Here’s the owners manual if you don’t have one

https://downloads.hearthnhome.com/installManuals/Invincible_T.pdf

 

[Washed-Up]

Maybe time for the leafblower clean/trick

 

[Pitou]

Thanks! I already have the manual. I also think it's air draft issue, but cannot find where!

 

[Washed-Up]

Door gaskets ash gaskets and hopper gaskets good?

 

[Pitou]

yes all gaskets are good. I was re-reading the manual, but I'm not sure I understand the air flow on page 4.

The distribution blower push air to the primary channel out of the burn pot holes?
Or the distribution blower push air in the secondary part?

Can someone enlighten me on how and where the air flows?
Thank you.

 

[johneh]

The combustion fan pulls air through the burn pot, over the heat exchanger
and pushers it out the chimney
The Distribution fan pushes air to be heated through the heat exchanger
and out into the room AKA convention fan

 

[Pitou]

Thanks for the explanation @johneh. However I did remove the burnpot completely and cannot see where it goes and how it joins the combustion motor. Does someone has a schematic of all the tubes and how they are connected? In the manual, it's not very obvious.

Btw, the burnpot and the tube behind it are all clean. I also doubled checked the other tubes/channels and all is fine as well. I'm really out of idea.

Thanks for your help.
Pitou!

 

[Tim_M]

Have you cleaned the square heat exchange tubes that are accessed by removing the steel L-shape cover located at the bottom of the stove on each side? If there is a blockage in your stove, that is most likely area. You should also remove the 2 baffles located in the firebox and ensure the openings at the bottom are clear of ash.

The combustion blower pulls air through the stove. It’s drawn in at the rear through the flapper opening in your 2nd photo. It travels through a channel directly under the auger tube and into the burn pot where it’s drawn through the small holes to the burning pellets. It continues to the top of the burn pot and then down behind the steel baffles on either side. At the bottom of each is a square opening where the air passes into the heat exchange tubes - up the outer tube and then down the inner one - before being drawn through the horizontal tube connecting them. Finally the air is drawn through the combustion fan itself and pushed out the vent/chimney.

 

[Pitou]

Hi @Tim_M!

Have you cleaned the square heat exchange tubes that are accessed by removing the steel L-shape cover located at the bottom of the stove on each side?

Yes I did. I removed both L-shaped covers and clean that. I can see through from left to right. I also but the brush up in those tubes (left and right) and it goes up very far until it stops. Not sure how many inches, but I can double check.

You should also remove the 2 baffles located in the firebox and ensure the openings at the bottom are clear of ash.

I also removed these 2 plates with a hole in the bottom and poked the brush in the 2 squares kind of angled holes. It inserts only a couple of inches.

The combustion blower pulls air through the stove. It’s drawn in at the rear through the flapper opening in your 2nd photo. It travels through a channel directly under the auger tube and into the burn pot where it’s drawn through the small holes to the burning pellets. It continues to the top of the burn pot and then down behind the steel baffles on either side. At the bottom of each is a square opening where the air passes into the heat exchange tubes - up the outer tube and then down the inner one - before being drawn through the horizontal tube connecting them.

Great explanation! Thanks. Now about the heat exchange tubes. I know (probably) that both left and right tubes are vertically fine. Horizontal at the bottom as well (connecting both of them). Between the vertical tubes, what's happening at the top? Is the inner tube accessible by removing the stoves's top?

See my drawing. That's my attempt at trying to understand!

Pitou!

 

[Pitou]

I found the issue

I just notice there are 2 vertical tubes just beside the external ones

Works like a charm now!
Thanks everyone.
Pitou!

 

[Tim_M]

I’m glad you were able to solve your problem. One other thing to keep in mind with Harman stoves is the importance of having a good seal on the hopper lid. You’re probably already aware of this but if air leaks through the lid seal it will be pulled through the auger tube into the burn pot. This will cause the fire to burn hot at the throat of the auger tube, which can eventually lead to degradation of the steel in this area.

 

[Pitou]

Thanks for the reminder Tim. According to these pics, would you say it's still good?