Smokey chimney

[Bek1234]

I’ve noticed recently that our lounge that has an open fireplace often smells very smoky in the mornings when I come down. I notice this especially when it’s a warm day outside.

also, often when I light a fire, smoke billows into the room until it gets hot enough to draw it up the chimney.

we get the chimney swept regularly so there’s no blockage.

We have a cowl on the chimney to stop birds and rain coming down. Not sure if that’s relevant.

I’ve read that it could be something to do with negative air pressure but I don’t full understand the physics of it…what do I need to do to combat it?

 

[foxhole]

How are you lighting a fire, do you have vents in the room to the outside?

 

[Bek1234]

Not sure what you mean, lifting? No vents as such…there are windows in the room but closed in winter.

 

[Burnerman]

Geographically you may live in an area that is prone to down draught......have a look at other property chimneys - do they have special or odd looking cowls on top?
Chimneys of course can hold very dense and cold air, that is difficult to shift until the fire gets going, but if you can smell it in the morning it's likely that outside air is coming down the lum.
As Foxy says, the fire needs ventilation to take the combustion gases upwards - therefore air must come into the room for this to happen.
John

 

[Lower]

Have you got an extractor fan elsewhere in the house, like a kitchen or bathroom one? If you have, and the house is well sealed otherwise, the air that is extracted has to be replaced, and the replacement air might be coming down the chimney.

 

[Bek1234]

We have an extractor fan in the bathroom that’s on sometimes. The bathroom window is always open too.

Is there an easy solution? Opening a window in the lounge? Although that’s not ideal in the winter.

 

[Lower]

Have any of your windows got trickle vents?

 

[Burnerman]

Open fires belong in older, traditional properties with ill fitting doors and windows.....i.e plenty of draughts!
If you have the usual upvc windows and doors etc then ventilation may be compromised - so give the fire some air when lighting up.
A wood burner may be a reasonable alternative.....you can have one up to 5kW output without extra ventilation, but larger than that needs a vent to outside in the immediate area to draw air in.
John

 

[Bek1234]

The house is old, from about 1900, so I would’ve thought quite drafty! Although we do have UPVC windows in the lounge.

So do you think it’s a good idea to open a window when lighting the fire at least? That will stop the smoke billowing in?

 

[Burnerman]

For sure, to allow hot gases to rise up the chimney, you need air coming in to the fireplace.....give it a try, leave a few connecting doors open so air can enter the lounge.
You can see if the chimney is drawing when cold.....get some smoke pellets from a plumbers merchant and set one off in the fire grate.
John

 

[cwhaley]

I can't add anything new to your post, but I can reiterate - from experience - the posts from the ever-knowledgeable burnerman. We re-instated an open fireplace in our dining room a few years ago and suffered the same issue as you, sometimes smoke would also come down a separate flue and into the front room (unless the stove was lit in that room meaning hot air was pushing any smoke up).

The solution was to crack a window in the dining room open during the lighting stage. The influx of fresh air was sucked straight up the flue and meant we had a good, strong draw. If the front room fire was unlit, I had to keep the door into that room open otherwise it would start filling with smoke. I did put an airbrick in which I found helped a little, but as we've extended onto the back of the house thus cutting off the fresh air supply I'm converting it to a little stove.

 

[Harry Bloomfield]

The house is old, from about 1900, so I would’ve thought quite drafty! Although we do have UPVC windows in the lounge.

So do you think it’s a good idea to open a window when lighting the fire at least? That will stop the smoke billowing in?

I would suggest that opening vents or windows a little on the windward side would help pressurise the house and help push smoke up the chimney, until heat rising begins to take over.

 

[foxhole]

Old house will have vents in most rooms , have they been sealed.?

 

[Bek1234]

I'm still having trouble with this. The smoking during lighting isn't such a big deal as I can just open a window till the fire is burning which is fine, but the cold draught and smokey smell in the day, when the fire isn't in use, is a real pain. It makes the room really cold and the whole house smell.

I'm just not sure what a solution to this could be. I've read about anti-downdraught cowls - do they work?

 

[Burnerman]

In this situation, do try the smoke pellet trick.....Screwfix do them in ten pack tubs. If the chimney doesn’t draw then the (harmless) smoke won’t disappear.
Anti down draught cowls do work, but the issue is finding which type is best for you.
Consider contacting a local Hetas firm for their advice, or failing that I get a lot of stuff from fluesystems.com and they have a few designs available.
John