The smallest ones I have seen are 4- 5 kW. I would suspect that the temperature required for efficient combustion and the need to load at convienient intervals make smaller stoves impractical and/or inefficient. Do you have a specific requirement ? The output of a stove is tested with manufactures conditions stated on the test report. I do not know the practicalities or efficiency drop if the stove is run at say 50% of rated value.

Richard

I can recomend "stovesonline.co.uk" The chap who runs it is also on this forum and his website is very informative and if you contact them for advice they are very helpfull.

Are you in a smokeless zone?, if so they list stoves that meet this requirement and some stoves have a conversion kit to comply.

Shevek, I agree with you. Viking House has stated on other threads that he has had customers insist on wood burning stoves in his Passive houses but mostly not used and some consider them to be a cold radiator. I, like you, want a small stove and think it is nicer to look at than the TV most of the time. Also even passive houses need some heat when it very cold outside and what is more welcoming than a real fire (even if you have to leave doors open to dissapate the heat). This is also a reason I am a fan of thermal mass, run the stove for a time and heat the mass to keep you warm afterwards. Also, UFH is no good for chesnuts at Christmas

@Shevek have you considered using a bioethanol stove/fireplace. They can be quite cheap on a well known auction site. Output is quite low, a few kW, no chimney needed and no clean up :-) I'm considering one for my renovation.

Posted By: cullym@Shevek have you considered using a bioethanol stove/fireplace. They can be quite cheap on a well known auction site. Output is quite low, a few kW, no chimney needed and no clean up :-) I'm considering one for my renovation.

Wow, yeah, that's an interesting thought. Do they need an air supply?

I wonder if it could go into the fire place when we're installing Ventive ventilation to the chimney too. I think it probably could.

@Shevek the byproduct from combustion is water vapour and carbon dioxide so you will need some ventilation. As GaryB has suggested the min ventilation rate of the Ventive may be enough. In my case I'll have a supply from the MVHR in the room which I think should be sufficent (something I still need to verify).

@Shevek the bioethanal can be bought in bulk for about €1.50 to €2.00 per litre. I think the rate of consumption will depend on the actual stove/fireplace but one FAQ I have bookmarked says:

"Each litre burns for 4 hours on maximum setting, however most of the burners are adjustable and the burning time can be increased to 6 hours if the settings are reduced."

I'm still researching these, one thing that concerns me is safety both in terms of storing fuel and also the design of some of the fireplaces.

Looking at a Rika Vitra Passivhaus 2-4kw wood burner for our near passive spec build, lowest one I could find.
Apart from mega priced ones from Tonwerk.

I'm going for a bioethanol burner also.

When you look at the combined costs of installing a flue and a room sealed stove the figures are crazy £5,000-£10,000.

Add in the issues with cold bridging caused by both the flue and the air supply and you have to ask yourself why are you spending a large lump of money to give yourself more problems for something that is going to be lit on a handful of winter Sunday afternoons?

From what I have read a bioethanol burner puts out a similar amount of CO as about 4 large candles.

Will be fitting a CO alarm in any case.

Burley stoves do efficient woodburners in 3kw (88.9% efficient), 4kw (89.8)or 5kw (89.1). I fitted a 5KW at my parents and its a very good stove. I did some haggling over the price and saved over £100 off the RRP (paid £710 last November-inc delivery)