Log Burner - Smoke in Room

[cwhaley]

I have ran wood burning stoves for 10 years and had no problems. I've always had the flue swept and inspected once or twice yearly and I only burn dry timber.

I decided to swap my old stoves for two new DEFRA wood burners as they are slightly larger and more efficient. I also had new 5" liners installed (recommended size for these stoves). The height of the flues is 9 metres straight up to an open pot with a 'bird cage' on the top.

I now have problems with getting a good draw. I can just about stop smoke entering the room during reloading, but it's a bit of an art and I notice that the draw isn't particularly strong. I also notice white smoke during the early stages of a reload, which didn't happen before.

Previously cracking the door open on my stoves during a burn made it sound like a jet aircraft. Never had any issues and the setup fundamentally hasn't changed.

The only difference I've noticed is this 'secondary baffle plate' which can be seen on this crude illustration. It sits above the vermiculite plate and is held in place with two hex headed screws. I presume its aim is to promote increased burning of exhaust gases, but in doing so reduces draw.

Anybody else had or heard of this issue?

 

[Tetrarch]

I have a Stovax wood burner and I deliberately increase the ventilation before opening the door as this seems to help with smoke and fumes

Regards

Tet

PS This is after a loong and smokey experience when I first had it. I learned how to pre-heat the stove with a heat gun to kickstart the draw and now have no smoke ingress at all

 

[cwhaley]

I have a Stovax wood burner and I deliberately increase the ventilation before opening the door as this seems to help with smoke and fumes

Regards

Tet

PS This is after a loong and smokey experience when I first had it. I learned how to pre-heat the stove with a heat gun to kickstart the draw and now have no smoke ingress at all

Thanks for the reply. I have two old Victorian sash windows which I crack open when lighting, but will open them more as an experiment. The stoves are served by a controllable air vent behind them (outside walls), which I hoped would help.

I start the stoves with a strong fire made from strips of pine and lighting them is easy, it's just much less of a draw than I had before. I'll try with the heat gun I have to see if it works - how long do you heat it for in your experience?

 

[Burnerman]

I have two Morso 4kW multifuel burners.
Similar to yours, mine had a cupped baffle just below the flue exit - designed no doubt to slow the burning gases down. The only way I could get the stoves to perform well was to remove the baffles, and all is good now. Granted, the efficiency may be down somewhat but I can live with that!
John

 

[cwhaley]

I have two Morso 4kW multifuel burners.
Similar to yours, mine had a cupped baffle just below the flue exit - designed no doubt to slow the burning gases down. The only way I could get the stoves to perform well was to remove the baffles, and all is good now. Granted, the efficiency may be down somewhat but I can live with that!
John

I'd considered that, but I suppose I was looking to see if somebody else had been there and done it!

The first baffle (a metal frame with a vermiculite brick insert) obviously restricts the pull of air and will stay, but it's the second cast iron baffle restricting it even further. I'll run it without as a test run (weather thankfully nowhere near cold yet to warrant using them..!)

 

[Tetrarch]

Thanks for the reply. I have two old Victorian sash windows which I crack open when lighting, but will open them more as an experiment. The stoves are served by a controllable air vent behind them (outside walls), which I hoped would help.

I start the stoves with a strong fire made from strips of pine and lighting them is easy, it's just much less of a draw than I had before. I'll try with the heat gun I have to see if it works - how long do you heat it for in your experience?

About two minutes on full chat

I turn it off when I can feel the back of the flue feeling noticeably warm to the touch.

I use a firelighter (one of the woven straw-y ones) and some very light kindling.

I now get very little smoke smell in the house when using the burner. Bizarrely, the other day we had more smoke smell from our incoming MVHR inlet than from the burner itself

My burner has an adjustable vent plate that controls the burn really well

Regards

Tet

 

[ericmark]

I don't have a wood burner here, well open grate but never used. But, where I have used solid fuel, best was to light a fire before dawn before the air on top of the roof heats up.