Bringing in air for open fire

If you have a suspended floor with air bricks for ventilation all you need to do is put a grille in the floor as close as possible to the hearth.

You may get much more efficient heating if you use a multi-fuel stove instead of an open fire.

Cheers

Dave R

Agreed and if one can be put either side and so made smaller then all the better. Obviously fit shuttered ones so that the ventilation can be adjusted to match the weather and the level of the fire.

Although a note of caution - with stoves the vents must not be 'hit and miss' for safety reasons.

Cheers

Dave R

If a multifuel stove has a nominal output of less than 5kW then an air vent is not mandatory (except in new very airtight houses) - so you could have one placed for minimum drafts, and use a hit and miss vent. Over 5kW a permanently open vent is a building regs requirement.

Alternatively you could look at stoves with a piped air inlet, if you have a suitable outside wall near the stove.

Finally, having put in a woodburner this winter I would concur about how much more efficient they are than an open fire - we have spent most of the (albeit mild) winter learning how to control the output of our little 4.9kW stove to avoid overheating ourselves....

Charles F

This is something I've always wondered. Is it possible to have a woodburner that provides a low lingering heat efficiently (ie full combustion, no soot), or are they all like blast furnaces that consume logs in seconds?

Theo

Turn the air control down. Our woodburner will lasts all evening on two or three logs.

Though better than an open fire, the traditional wood burning stoves are inherently inefficient in that all the volatiles are not burned off. (That's why you can smell woodsmoke) For that you need a pyrolising stove which has two chambers, in one the wood is pyrolised, in the second the evolved gases are burned off with a separate air supply.

Even if you have a solid floor you may still be able to run a duct through it if you don't mind digging a channel in the floor.

My in-laws' 1960's bungalow had a built-in under (solid) floor duct which fed air pretty much to the underside of the fire basket (can't remember the exact details) and that always seemed to work pretty well.

Pretty sure that was made by Baxi. Doubt whether they still do them, though.

Nope, no smell of wood smoke now that combustion has stabilised, just a haze of hot air at about 150C coming out of the flue. There's no smell of coal smoke when that's what's burning either.

Next door, on the other hand have a posh expensive stove with a pyrolising chamber and full control over the air entering at various points, and their stove *always* smells of whatever's being burnt. It's always smoking, too...

We have got the hang of it now, and yes, you can run a 5kW stove at an estimated 2kW output by reducing the air supply, once it is properly up to temperature. Probably not much less than that though... Overall it's been a great sucess, easy to light and control, and comfortable to live with.

Charles F

Dunno about regs for open fires, but my gas safe man wouldn't allow a floor vent and insisted on venting through an outside wall. We fitted a 'black hole' vent in the equivalent position to the top of the 'T' where it says TV on the sketch and haven't noticed any draughts etc from it.

The secret, for "cheap" (single chamber) ones, is to make sure you have good seals on the doors, also look out for gaps opening up between the castings, typically between the top and the walls, which let in uncontrolled air. These are easily filled with fire cement. Glass fibre rope and adhesive for the doors is available from good hardware shops, or eBay. You can also control the airflow with the damper in the flue. At the point where you get smells in the room, the damper is closed too far.

You will also be better off with *large* lumps of well dried wood. With damp wood, you come down in the morning to a cold room and unburned wood. A few large lumps is better than several small ones because it reduces the surface area to volume ratio; for a given weight of fuel, they will last longer when the airflow is damped down.

Thass about what we find too. Just feed it less wood and adjust the air down carefully so the flames are still agitated but not manic. If the flames are lethargic you'll get deposits on the glass.

I think the above is due to the possibility of underfloor vents getting blocked by a dead rat/leaves etc.

Baxi Burnall ? I have one, others on this group have clones, it is still available and all spare parts. Info in various places, for example

Simon.

We're just looking in to this. With the draughts we have (1) I'm sure we don't _really_ need one at all. But rules is rules...

Andy

(1) For example - the meter cupboard door keeps blowing open.

That certainly looks like the right thing - although I don't specifically remember the name "burnall". Did Baxi ever use any other name for that system?

Solid floor.

In retrospect that would have been the best thing to do instead of having open fire with boiler. Too late now and still need to bring air in from somewhere.

Yes my previous next door neighbours had this. A bit of a pain to get the ash out though as they had to let the fire out to do it. I've gone up to 10 days without letting it out. The new neighbours have taken it out though I don't know why.

I probably could run a duct on the floor inside the cupboard and drill a couple of holes to let the air out into the fireplace. It's not an air tight cupboard anyway.

It seems a lot of work to dig a channel to be honest.