Tar bubbling just above the woodburner

[JohnJohnJohn]

Hi,

 

I've just had to sweep my chimney and cleared out a huge amount that had actually fully blocked the flue. My hat had broken off in some recent wind and I think a fair bit of moisture had got in, alongside previous owner never cleaning.

 

I've just managed to refit the 'baffle plate' (perfect name..) and light the fire for the first time in a while but just where the stove is sealed to the chimney it started bubbling tar.

 

Am I burning under seasoned wood or is this just the chimney drying out? Is this a serious problem?

[magnetman]

Probably the fire is going too slowly and the wood is not fully seasoned. 

 

A very hot fire will burn anything including green wood but most fires are too big to be able to run them at a high temperature safely in a confined space. 

 

If you think you might be burning under seasoned wood then you probably are. 

 

 

I think the bubbling probably is just the rope drying out but if your flue is getting blocked the fire is not running hot enough. 

 

 

[Tony Brooks]

I note that there does not appear to be any sealant on top of the rope. Most seem to use high temperature silicon nowadays or some form of fire cement.

[Tracy D'arth]

If it is just rope sealing the collar then any moisture will cause it to bubble.  Get some Envirograf super temperature silicone sealant and flaunch the collar over the rope.

[Machpoint005]

I've used that Envirograf stuff. It's really good.

 

And really expensive!

 

 

[Arthur Marshall]

I took the baffle plate out. It just cuts the draught down too much - be fine if you had a twenty foot chimbley as per manufacturers instructions. All that happens with a baffle plate is that the gunk that condenses and comes back down the flue sits on it, sets like rock and cut the draught down even more. They're a menace.

[JohnJohnJohn]

Thank you very much everyone! Puts my mind to rest, I can finally enjoy the warmth!

 

I'll also get some sealant, I hadn't thought about that at all.

[magnetman]

2 minutes ago, Arthur Marshall said:

I took the baffle plate out. It just cuts the draught down too much - be fine if you had a twenty foot chimbley as per manufacturers instructions. All that happens with a baffle plate is that the gunk that condenses and comes back down the flue sits on it, sets like rock and cut the draught down even more. They're a menace.

 

Yes they are a menace on larger fires. I think the problem boils down to the fact the fire itself is much too big for the space being heated. Therefore it never gets up to a proper temperature. A hot fire (600C+ firebox temperature) with proper secondary burn will tend not to have the same problems because combustion products are expelled and the smoke is burnt in the fire itself reducing the soot problem. 

 

 

[Sea Dog]

3 hours ago, Machpoint005 said:

I've used that Envirograf stuff. It's really good.

 

And really expensive!

 

 

Thirteen quid as a carbon monoxide death prevention measure? I said "sod it" and splashed out! 

 

As you say, it is bloomin' good. I used Vitcas 300c stuff at the top - claggy and horrible. Should have used 1200c Envirograf both ends. Perfect finish very easily achieved, plus the transparent version I used took grate polish well to make a perfect match with the stove and flue in one application. Buy the best - cry only once. 

[MtB]

Just one observation, the Envirograf site says "Do not use on boilers, hot flues, or stoves"

 

After saying:

 

"Can be used on log stoves in areas where there are no flames."

 

They should make their minds up!

 

https://envirograf.com/product/silicone-sealant/

 

 

[Chewbacka]

On 12/11/2023 at 19:26, MtB said:

Just one observation, the Envirograf site says "Do not use on boilers, hot flues, or stoves"

 

After saying:

 

"Can be used on log stoves in areas where there are no flames."

 

They should make their minds up!

 

https://envirograf.com/product/silicone-sealant/

 

 

Maybe wood burners (areas without flames) are cooler than coal boilers?

[magnetman]

 If the fire is opened up the flames can get into the flue.

 

The only places flame rarely gets is below the grate. I've had flames coming out the chimney when using accelerants. No need for any sealants on this fire due to the design. 

 

 

Edited November 15, 2023 by magnetman

[Mac of Cygnet]

On 12/11/2023 at 15:08, Machpoint005 said:

I've used that Envirograf stuff. It's really good.

 

And really expensive!

 

 

Just make sure that you can evacuate the boat for half an hour when the stove is lit after using it.  It produces some of the most noxious fumes I have ever experienced.  OK once cured.