Black liquid coming down flue at back of stove

heavydawson

Hey all,
Recently finished a new build and was lighting stove only to find that about 20 minutes after lighting there was a blackish sooty smelling liquid coming from the flue and coming through the fire cement where the stove pipe meets the chimney flue (pictures attached). It seems to be temperature related because when the fire is blaring we see nothing, but when the damper is closed you can predictably wait a few minutes before it appears again.
I searched already on the internet and it seems the liquid is creosote (sooty condensation), and the problem is the gases from the stove cooling too much or being too moisture laden before they escape the chimney.

I went and bought a wood moisture meter to check the timber I was using (it's all off cuts from the house skirting and architrave) and it's all pretty much bang on 12.5%, so should be perfectly suitable for burning.
The stove installation manual recommended that a flue line is only required for those flues above 8", and ours is 8".

I suspect I'm going to need to pull out the stove and install a flue liner. Has anyone had similar problems and has a flue liner rectified them?

FWIW the house is two stories and the chimney breast is a double breasted with another flue behind it.

Link to the album showing the liquid
http://imgur.com/a/r9TbL

robertxxx

AFAIK your stove is not burning hot enough, a flu would help as it would help keep the smoke hot so it escapes easier.

fredgalway

Hi Heavy. Good advice from Robert as regards size of fire. It makes no difference what moisture content your timber is,. if the fire is not hot enough you will have condensation. I personally do not favour installing a flexi flue if at all possible and it should not be required in a new build. Put on a better fire, but do not overdo it as your flues are new and too large a fire will crack them.

heavydawson

Is it reasonable to expect the condensate to be coming into the room though? (As opposed to coming back into the stove via the stove pipe?).
It throws off some smoke when it touches a hot surface (running down the outside of the stove pipe) and it smells terrible.
Will get a stove pipe thermometer and check the stove output temperature. If I find it's between 250 and 450 degrees and still condensing, then I'm guessing I'll be needing a flue liner.

DECY15

Hi just wondering if you got your problem with cresote sorted ? I have same problem with solid fuel boiler which is flues into 8 inch clay flue and thinking of flue liner too .

heavydawson

DECY15 wrote: »

Hi just wondering if you got your problem with cresote sorted ? I have same problem with solid fuel boiler which is flues into 8 inch clay flue and thinking of flue liner too .

Turned out to be the external air supply pipe filling up with water. Once that was cleared, creosote disappeared.