How to stop chimney creating draft

[Roger465]

OK, I realise (1) this isn't plumbing or central heating (couldn’t find anywhere more appropriate); (2) the title isn't really correct either…

Anyway. For predictable reasons, we’ve started having fires – normal fireplace, traditional grate, dry wood and peat briquettes – but have discovered that, if we close the living room door, smoke comes into the room quite badly. Open the door and it stops; leave the door open and we get an unpleasant cold draft.

Now I know hot air rushing up the chimney needs to be replaced from somewhere, so cold air has to come into the room, but what do people do to avoid the resultant icy blast, which kind of defeats the purpose of having a nice warm fire??

 

[muggles]

You need an air vent drilling through the wall to outside, of an appropriate size and type to provide combustion air for your fire.

You should also consider getting a stove installed - they use half the fuel of an open fire for the same heat output

 

[Justin Passing]

Smoke comes into the room?
We can't tell what your "living room" is.....

SOunds like the chimney's maybe just cold. Open the door to let the fire heat the chimney - then it'll work. If warm air doesn't get to the top of the chimney, it won't pull cos it's trying to push dense cold air up out of the way. Once it's warm it should be OK and draw through small gaps, etc., but it does need fresh air from the house.

Nominally, all solid fuel open fireplaces need an air vent and the size of the air vent should be 50% of the throat opening to the chimney.
In the case of a wood burning stoves or room heater, if the appliance is under 5 kw normally you won’t need an air vent but you still need to test it. But if it’s over 5 kw you do need an air vent. If the house was built before 2008, the air vent size would need to be 550mm2 per kW over 5kW. So for an 8kW appliance an air vent of 1650mm2 would be sufficient. If the house was built after 2008 (and so is much better insulated) the air vent size is calculated at 550mm2 for every kW, so for an 8 kW appliance an air vent size of 4400mm2 would be required. Vents must be non-closable.
If you think you've got it OK< find somethin g which makes sme smoke like paper rolled up tight and blown out, and hold it near rhe top of the fire opening to see if gases are being drawn into the chimney, or out into the room. If the latter, you will die regardless of any figures.
Mos people don't have adequate vents and get up and move when they feel bad. Unless they fall asleep, then they wake up dead.

 

[Johntheo5]

I would get the chimney cleaned as a start.

 

[Exedon]

I would get the chimney cleaned as a start.

Plus stick a camera up it at same time most sweeps now do it.

 

[Roger465]

Thanks for all the replies, and sorry if I haven’t explained things properly.

The house was built in 1994; the living room is just a normal room, maybe 20’ x 20’. Double glazing.

The chimney was cleaned last year, and used very little since then.

It draws fine, absolutely no problems, but we sit with our backs to the door, and there’s quite a cold draft on our backs when the fire is burning. The door is quite well sealed when closed – but when we close it to stop the draft, smoke starts to come into the room immediately. I’m guessing that, when we stop air coming in that way, it has to come down the flue – has to get in to replace the hot air somehow…

I suppose an air vent is the only answer…

 

[Lower]

Quote simply, the smoke is carried up the chimney by air movement. If the room is well sealed and no air can get in when the door is closed, you won't have air movement up the chimney as there is nothing to replace the air that goes up the chimney, ie the draft that you feel through the door.

If the chimney smokes that quickly with the door closed, I'd also be worried about carbon monoxide as the fire will be starved of oxygen.

An air vent close to the fire the the answer.

 

[Roger465]

If the chimney smokes that quickly with the door closed, I'd also be worried about carbon monoxide as the fire will be starved of oxygen.

Believe me, with the door closed you couldn't sit in the room for long enough to worry about it

 

[Madrab]

I think you need a chimney specialist in to inspect and ensure it is ok. As suggested it does sound like you need a vent that is open when the fire is used. That can be on the floor nearer the fire to minimise draughts into the room.

Not suggesting it isn't but what class of chimney it is and is it actually designed for open fires? Not all are. The reason for the question is, if there is a chimney designed for an open fire then the chimney should have been tested as part of the commissioning process and adequate ventilation should have been considered and installed if required, as part of that.

 

[Roger465]

Not suggesting it isn't but what class of chimney it is and is it actually designed for open fires?

Oh, yes, it's a traditional fireplace - been there since the house was built.

Knowing the previous owners though, I wouldn't be at all surprised if they'd papered over the vent, if one was installed when built.

Here's a couple of pics of other handiwork of theirs. And the guy works in property maintenance for the local council

To be fair, I knew about at least some of it whan I bought it, so I got it cheap...

I think the shelf is the best

 

[Madrab]

Check on the outside walls of the 'lounge' for an airbrick or vent.

 

[Roger465]

Check on the outside walls of the 'lounge' for an airbrick or vent.

OK... well... here's the thing. No vent, no sign of ever being one... BUT there is a gas fitting (no sign of it anywhere on the inside), so I assume that was the original arrangement, but the previous owners must have done away with it and put the grate in.

Does that mean that the flue is likely in some way to be unsuitable for my open fire? It does seem to work perfectly well as long as there's some ventilation

And wouldn't a gas fire still require ventilation too?

 

[Madrab]

If possible can you can take a couple of pics of the fireplace, one inside of the fireplace, one or 2 pointing up inside the chimney showing the internals of the flue, one outside of the chimney and the terminal/pot on top.

Typically though a class one chimney for open solid fuel fires will be brick built with a large diameter inner flue >12", up to a roof stack with a clay pot terminal.

As far as a gas fire requiring more than adventitious ventilation then that would depend on the size of gas fire (the kw input rating)

 

[Roger465]

If possible can you can take a couple of pics of the fireplace, one inside of the fireplace, one or 2 pointing up inside the chimney showing the internals of the flue, one outside of the chimney and the terminal/pot on top.

Okily dokily...

 

[Madrab]

Certainly looks like a class one brick built chimney but not sure about the flue, you want to measure the inner flue diameter. It also looks like a clay cast fireback, the type with the integrated chair, they would usually be ok for solid fuel but would need to check if that can take the heat of solid fuel as it now seems to be cracking.

The terminal doesn't look quite right either, though that may just be the cowl sitting on a clay pot below.

Of course I'm not suggesting it isn't suitable but I'd deffo get a chimney specialist in to survey that and make sure everything is ok, especially if it isn't pulling correctly.