Restricting chimney to retain heat

[Nicky France]

We have just bought a lovely old french house with an enormous fireplace.  The chimney is huge and I have a feeling that it will not only draw all the smoke away from the fire but also all the heat.  I am sure I read somewere that you can put a construction in the chimney to retain the heat whilst letting the smoke out??  Could anyone let me know what this is and how it works.

Many thanks,

Nicky.

PS.  Anybody know any good French outlets/websites for second-hand log burners.

[Anton Redman]

Baffle - there is a very good description in the 'English Fireplace' of how this developed. Basically until the fire is drawing well the air flow is unrestricted but once the chimney has heated up the hot air is diverted to warm the room first. There are not many jobs I would not tackle myself but this is one. Sugest installing a free standing stove or using a specialist.

[Mysfloss]

Do you mean reducing the flue size and taking off hot air pipes?

[Hegs]

Have a look under Chauffage/Chauffage au bois/Récupérateurs de chaleur on www.castorama.fr

"Récupérateur de chaleur, puissance 5kW / h environ, pour cheminée. Equipé d'un système de filtration et d'un filtre. Dimensions : L 50 x H 21 x P 53 cm."

I have no idea how or whether they work, we went for a wood burner/register plate which works great.

[Nicky France]

wood burner/register plate

We have also looked (briefly) at wood burners but can you explain what a "register plate" is.  Sorry to be a bit ignorant about this but we only bought our house a few days ago and we are on a steep learning curve at the mo!

Nicky.

[Poolguy]

Nicky

Can I ask, what area are you hoping to heat with the extant chimney?

I presume that presently it is a straight passage from your main room to the heavens above. If that is true are you interested in modification to the chimney to retain the original open fire or are you going for an option which will maximise your heat yield for fuel input.

If its the former then I can send you a design for construction of sloping soot shelf and chimney pot which will largely eliminate unwanted draft and help the chimney to draw.

If you want the later then I would talk about wood pellet/chip burner unit to insert.

 

Andrew

[Hegs]

A register plate is something insulating and non flammable that sits in the chimney just out of sight that the flue from the stove passes through. Ours is made of thin steel, imagine a steel plate with a circular hole in that blocks the width of the chimney and you will not be far wrong.

[Nicky France]

Thanks for all the info.

Andrew...we were thinking of installing a wood-burner in the fireplace itself which will (presumably) involve putting a flue up the existing stone chimney.  We figured this will be more "controllable" than just a regular "open hearth".  This house is to become our primary residence and when we stayed there recently we noticed that there was a horrendous draught flying up the chimney and I imagine this would need solving even after you had installed the burner?  The room we are trying to heat is about 20m2 and the fireplace itself 1.7m high, 1.7m wide and about a metre deep.

Any ideas gratefully received.

Nicky

[Dave&Olive]

try this for information   http://www.backwoodsman-stoves.co.uk/index.html

or this  http://www.cashin-france.com/accueilA.swf

Dave

[Poolguy]

Nicky

I think that I understand your situation.

What I am not sure of is whether you want to retain the open fire or whether you want a furnace type of heating appliance inserted into the cavity in the solution. Both are possible to achieve to solve your problem.

Essentially, the chimney is as I understand it, an uninterrupted passage to the outside. This can be remedied and you can still have your open fire if that is what you want. It involves the construction of a soot self inside the fire place sloping towards the room and finishing at a distance of maybe 300mm (1foot) above the mantle piece on the inside. This is designed to choke the vent of air to make it accelerate while pushing the projection of heat out into the room. As the name implies it then creates a shelf to the back wall of the chimney. The exact size of the choke is determined by a formula relating the height of chimney, size of the fire place and volume of the chimney. You must add to that a baffle which can completely close off the choke to draft when you are not using the fire. You can also use this to manage your fire but this is a fine tuning refinement which needs a little little practice to avoid filling the room with smoke. The technology is simple and any maçon can do the work. But the design needs a little more thought and skill.

Alternatively you might choose from a world of inserts to burn solid wood if you want... they all work well and there is no use me adding to the noise.

However if you don't fancy the idea of feeding the fire with whole wood you can choose the woodchip/pellet option which is completely automatic like a oil or gas burner. That might be housed anywhere and comes in space heater of boiler sizes. With 20m2 to heat you are looking for a small space heater version. If you need more on this you can PM me.

Remember that wood is a renewable resource and its cheaper than the other fuels and always will be.

Andrew