Woodburner - cold chimney blows smoke back into room?

[buckaroo]

Does anyone know the best way to deal with this (hope this is in the correct forum?)

Anyway we have a woodburner with a chimney going through an outside wall.

With the cold weather, after lighting this, the smoke seems to blow back and fill the room. I hear this is quite common and you need to warm up the chimeny first as cold air forces the smoke back down??

We have tried the sheet of paper flat to burn up the chimney, but to no real avail. Is there a simple solution to stopping this, so before we actually light a fire, we can warm up the chimney for 5 mins beforehand?

Thank you for any advice

 

[Tibbot]

Make sure you've adequate ventilation. If so and it's still a problem, try opening window/doors to outside on lighting.

 

[Madrab]

Yup, simple convection, a warm room and chimney creates an updraught drawing air up the chimney, cold chimney, air can travel in both directions.
In the old hearth and coal fires in tenements with long flues, you used to have a heater for the chimney. A large, plug in, hot air heater on rubber feet with an asbestos tube on the front that sat on the hearth to pre-heat the chimney. Worked a treat.

If yours is especially bad then and hot air stripper gun or hot blowtorch to heat the fireplace for a few mins may be enough.

 

[ScottishGasMan]

When you say a chimney going "Through" an outside wall. Do you mean a regular masonry chimney that is on the outside wall of the house, or do you mean a metal twinwall style flue that goes through the wall then runs up the outside of the house?

While not exactly cost effective or convineint, a good blowtorch will start to heat it up cleanly with no smoke coming back in, used to have to do that sometimes before performing smoke tests on cold flues.

 

[buckaroo]

I mean a a metal twinwall style flue that goes through the wall then runs up the outside of the house..

I have seen that Before lighting the fire stack, keep a couple of pieces of newspaper nearby to roll up to act as torches. Light the torches and hold them in the flue area of the wood stove.

The heat from the newspapers is very hot and will work hard to push the cold air out of the flue and establish the draft....

 

[Madrab]

That would probably do, anything that will warm the bottom of the chimney initially would be enough until the heat of the main burn does it itself.

 

[Nige F]

Ideally a BIG old blowtorch ( like the roofers use ) but if you can't get one cheap consider a small Camping Gaz stove single burner on a small cannister- that will sit inside the log burner and warm the flue

 

[Norcon]

I'd sooner pull my chimney down than start using a blow torch every time I wanted a fire.

 

[Corgigrouch]

Leave the door on the stove open for a little while before lighting the stove so that warm air from the room gently warms the flue or chuck in a lit fire lighter just to get things going before lighting the fire in earnest..

It sounds like there is only a short length of vitreous before exiting the property..

 

[Lower]

Leave the door on the stove open for a little while before lighting the stove so that warm air from the room gently warms the flue or chuck in a lit fire lighter just to get things going before lighting the fire in earnest

That's what works for my fire

 

[Diyisfun]

When I get that problem, I light a couple of sheets of newspaper, leave the door ajar, 30 seconds later & its all sorted.

 

[woodrascal]

What stove are you using?

 

[Tipper]

Is the top of the flue high enough? It needs to be positioned such that downdraft is avoided due to the wind across the roof top. Does the fire smoke alot and spill out if the doors are open even when hot?