Fireplaces in modern houses

[andrewpreece]

You can get smoke candles to test the integrity of your chimney - I've never used them but a proper fireplace shop should sell them and if you do the test one day when there's no fire in the chimney you may get a better indication of where the leak is ( if leak there be ). I take it the fire does not feature a damper to adjust the airflow as it goes up the chimney? I have such a thing as an integal part of my fire and if you close it too far too fast with a roaring fire some smoke spills out, though not always visibly. Another possibility is that your fireplace is badly designed, perhaps with an arched top that allows smoke out, again perhaps onlya little so it isn't seen easily, but if you get smoke upstairs then it's more likely to be a leak. At any rate, a properly designed fireplace should have a flue area/fireplace entry area ratio within certain limits ( dunno what they are ). Finally, a badly placed chimney will suffer downdraughts ( the best place for a chimney is on the top of the roof, not partway up.

Andy.

[John Kelly]

Last year I installed a coal fireplace in our modernish (17 years old) house. It looks nice and gives a nice fire. However the room it's in can easily fill with smoke and also one of the upstairs rooms and we're not sure why. The chimney is clean (swept it myself) and the smoke appears to go right up the chimney and looking outside you can see it disappearing off into the distance.

Anyone any idea why the room gets very smoky or why one of the upstairs rooms gets smoky. It's annoying to have a fire and not be able to use it.

I have thought that it may be that the chimney isn't rendered between the ceiling downstairs and the floor upstairs so any gaps in the brickwork (good solid build these houses - not!) may allow smoke into the gap and then into the rooms but it only seems to affect one room and not the rest. Don't know where else to look so any suggestions welcome.

Thanks

[Rick Dipper]

Some suggestions,

If the smoke is comming out the top of the fire, there are some reasons why this may happen

The fire needs to burn hot, so less wood and more air gaps will get you a hotter fire, and draw the smoke up the chinmey. Putting too much wood on is a common problem.

you may get some blows of air down the chimney when the wind is blowing, if this is the case you will see ocassional pufs of smoke comming into the room

the fire may be too big/small for the chimney. There are some guidelines on this.

However the telling features of your story is the smoke upstairs, and my guess it your chinmey leaks, and that some form of liner is required.

Rick

[John Kelly]

Thanks Andrew and Rick. Some useful advice there. I think there's a combination of factors. I always start the fire with a generous helping of wood which I'll cut back on and see if that helps. I'll also see about this smoke candle and open the floorboards upstairs to see what happens.

Any idea where there would be guidelines on fireplace/chimney sizes? That sounds a useful avenue to chase up as well.

Thanks

[The Natural Philosopher]

I can tell you exactly, becuse I spent ages fixing my nrand new 'inglenooks' only to discover I needed hoods.

The aperture of the fire - the area of the fire that draws air into the chimney, should be no larger than 5, or at most 7 times the cross sectional area of the flue.

It also helps if the firelace is not a box with a hole in the top :-)

If smoke curls up under the lintle over the fireplace, the answer is to fit a plate to lower the lintel and reduce the aperture.

Rasing teh bed of the fire achieves the same result. The aperture is measured from the combustion surface.

If you do have a leaky chimney, it's not necessarily liner time, but you may need stick your head up the chimney and apply fireclay cement....

A 70's built chimney should be flue block lined already I think.

[rob w]

For a open fire you need a class one flue which i think is about 8 or

9 inches in diameter and the chimney has to be a certain hight above the roof. If its a class two flue for gas fires its 5 to 6 inches dia and i guess the rules on the hight above the roof is differant as you can vent a class two flue at the ridge tiles. Lining a chimney for an open fire can be done ive seen it on a web site, try "Anki" they make liners and may be able to assist i found them most helpfull when i was building my chimney. hope this helps Rob

[Rick Dipper]

A hood on one of my fire issues fixed the smoke comming out.

On another, I fitter a liner from hotline chinmeys, quite a game stood on a chinmey stack with a huge metal sasuage in the wind .....

Rick

[G&M]

I would guess the house is well sealed and there aren't enough draughts to provide the air the fire needs

[The Natural Philosopher]

That could be an issue, or simply a pooorly designed chimney, or blocked.

You do need to ventialte and open fire - mine have pipes going down to under the suspended floor, that leak icy draughts when the fire ain't lit :-)

SWMBO sticks vases on em in the warmer months :-)

Its easy to find out - just open a windows and if the fire leaps to life, you need more ventilation.