Stove size/rating

[Bayliss]

Currently we use a medium size Franklin open stove in our living room, it burns logs or coal but is only slightly better in terms of heat value than an open fire. For this reason, and of course the current fuel cost, we have decided to replace the Franklin with a proper stove, one which runs with the double airwash to help keep glass clean.
Our living room is 12' x 16' + a 5' x 6' bay window. The walls are a mix of lath and plaster and gable wall of single thickness brick. Gable wall and front wall are exposed to outside whilst remaining two walls are internal. We would burn logs and then occasional solid fuel.

Kw rating requirement much appreciated. Thank you

 

[Flyfisher]

You really need the height information to calculate the room volume but assuming 8 feet then this online calculator suggests 3.1 kW, though the usual caveats concerning thin walls and poor insulation apply so perhaps 4kW would be better.

http://www.stovesonline.co.uk/calculator.asp

 

[Bayliss]

Thank you flyfisher, sorry I forgot about ceiling height. Its only about 6'. I understand that the stove should be run when wood burning at around 65% of burn capacity? Thanks for link.

 

[Penners]

Flyfisher has found you a useful calculator, but remember that, without heat-loss figures for your walls, any recommendation will only be a rough guide.

You need to choose a stove which doesn't have to belt flat-out the whole time to heat the room effectively, but at the other end of the scale you also shouldn't overspecify it. If the stove is overly generous with its output you'll end up running it at tickover for a fair bit of the time, which can mean that your flue doesn't get hot enough to avoid condensation of the combustion products. This can pose an acid threat to your flue lining.

 

[masochists-r-us]

Hi Bayliss,
We have a similar size room and ceiling height to you, but 12 inch thick stone walls,a cellar below the wooden floor and a well insulated ceiling above. We have an 8 Kw Clearview. Based on the calculators this would seem to be oversized, but we think it's perfect.

 

[skier-hughes]

Whereas we had a 7kw in a similar sized room and it was far too big, it was often run at tickover, even with an open door to the rest of a very cool house. In the depths of winter on a particualry cold day it would be just about right!!

 

[Bayliss]

Thank you all for advise and comment, its much appreciated. Decided to go for around the 6kw and hope for the best, I shall go the used route on that large auction site. Most likely try and sell my current stove on there.

 

[Bayliss]

May I widen out the discussion and advise, has anyone ran a back boiler off one of the multi fuel stoves? I would imagine that a backboiler will use a fair amount of the Kw available from the stove box. Is it worthwhile to use one of these, I currently use an oil boiler which is installed in our small inglenook fireplace in our dining room. It was installed by the previous owner in just about the most awful location possible. I can remove the oil boiler and install a multi fuel stove connecting to the existing water pipes, it would certainly look far nicer and hopefully provide hot water for radiators and domestic water?
Thanks again for input.

 

[Penners]

Bayliss - I'm not absolutely certain what your question is, but I hope the following comments might help your decision.

A back boiler on a woodburning stove will, of course, heat water. But the heat isn't free. At any given moment the stove will be producing a given quantity of heat, and if some of that heat is conducted away by the back boiler, it won't be available to heat the room in which the back boiler stands (unless of course the backboiler is running a radiator in that room). So the woodburner/back boiler would have to be specified to the service you wish it to fulfil, in terms of room heating and hot water.

To provide all of the hot water necessary for the average central heating and domestic hot water system, you would need a pretty sizeable woodburner. And you would need to keep it burning for as much of the day as you wanted central heating - with the attendant attention to stoking it, etc.

Nevertheless, there's no reason why a woodburner back boiler shouldn't be used to supplement the existing central heating/DHW system, provided you're happy that you won't be robbing too much heat from the room in which the woodburner stands.

 

[Bayliss]

Thanks Penners for reply. Our dining room is 12' x 11'4'' with about a 6' high ceiling, double aspect windows as well. T he current oil boiler is ugly as sin being simply a white enamal floor standing box, and it smells of the oil . It was installed in 1997 although we spent a couple of hundred pounds two years ago on a boiler refresh.
I have decided it going to go after this winter/when we have used up our supply of oil. This will give us time to source and fit a stove, no problem stoking and doing the ashes and I think we could probably remove the existing pig ugly radiator in the dining room with the amount of heat from the stove should be adequate.
Another project then.

 

[Penners]

OK Bayliss. My only additional suggestion would be to ensure that you get advice from a properly qualified HETAS installer, who can tell you what size/specification of stove you ought to install, in order to satisfy your total heating needs.

You may have someone in mind, but in case it's of any use to you, we have used Colne Stoves, in Earl's Colne, twice in the past. We've found them very helpful, capable and efficient.

I know they're a little way from you, but I think they'd cover your area.

http://www.colnestoves.com/

 

[Flyfisher]

The specs I've read for stoves with back boilers give two figures - one for the boiler and one for the 'heat to the room', e.g. 24kW boiler / 4kW room. Of course it all adds up to a 28kW stove and that will burn a lot of wood.

I'm planning to install a boiler stove and to combine it with a 'heat store' so that the heat from a good burn can be stored for later use, perhaps to drive some radiators to take the chill off the winter mornings, but I haven't completely worked things out yet.

Some background here: http://www.stovesonline.co.uk/stoves_with_backboilers.html

 

[88v8]

The farmer down the road has a woodfired backburner that runs heating + water, and heats his whole (three bed 1970s) house, so yes it can work, but as has been said you would need to do a thorough heat-loss calculation for the house before buying one. This is long-winded but not difficult.
When I installed our heating in 1980, and previously in 1975, I used the calculation methodology of Ravensbourne heating, who I see are still in business and now offer a design service.
http://www.ravensbourneheatplan.co.uk/design/
I would think it worth getting in touch with them.
The heating in our house works well, and gives a good temperature balance in all rooms, and has been cheap to run. OK, it is gas.... I also used their guidance as regards pipe sizes and pump placement, so the system does not make swooshing noises and the rads never need bleeding.

Returning to woodburners..,. the chap who lime-plastered our dining room last week lives in Merthyr, he has a woodburner and keeps it in for two weeks at a time, after which 'it needs a good cleaning' . He keeps it in overnight by banking it with coal, which I thought an interesting idea.

If you were to buy a used woodburner with back-boiler you would need to be sure that it's not furred up or leaking.

Ivor

 

[Penners]

he has a woodburner and keeps it in for two weeks at a time, after which 'it needs a good cleaning' . He keeps it in overnight by banking it with coal

This would, of course, need a multifuel stove rather than a simple woodburner.

 

[Penners]

I'm planning to install a boiler stove and to combine it with a 'heat store' so that the heat from a good burn can be stored for later use, perhaps to drive some radiators to take the chill off the winter mornings, but I haven't completely worked things out yet.

Blimey! Those heat store tanks are pricey! I wonder what makes them so expensive. Obviously they have an outer metal jacket over the insulation, and a lot more tapping points, but that somehow doesn't seem enough to justify the fact that they're several times the price of an ordinary indirect cylinder. I must be missing something.

 

[skier-hughes]

I have a 40kw multi-fuel stove with back boiler, 900l heat store tank, solar panels for hot water in summer.
If you light the fire, you need to run the heating, it needs to be very well matched, to hot and the water will boil.
We burn tonnes of wood, but now have a warm house
If you want to know more details let me know.

 

[88v8]

he has a woodburner and keeps it in for two weeks at a time, after which 'it needs a good cleaning' . He keeps it in overnight by banking it with coal

This would, of course, need a multifuel stove rather than a simple woodburner.

Our 'woodburner' - so-called by the previous owners - has been in the house at least 18 years, is totally anonymous and came with no literature. How would one know the difference?

Ivor

 

[Bayliss]

Thank you all for your advise, much appreciated. Colne Heating we know well, we purchased a Boskey stove cooker from them back in the 1980's, I did wonder if they were still in business. They were an excellent company to deal with back then and clearly little must have changed all these years later. Only the better Companies survive.
Also thank you for the links, back to more homework.
P.S. The only difference between a wood only and a multi-fuel stove is the fire grate and riddle mechanism + ash can. Obviously if burning one of the modern coals the fire needs to be riddled free of sitting on its own ash, wood is opposite it needs to sit on its own ash bed.

 

[Penners]

The only difference between a wood only and a multi-fuel stove is the fire grate and riddle mechanism + ash can.

Yes, that's about the size of it. Although you also need bottom ventilation (don't we all ?) If the only air vents are the top "air wash" ones, I'm not sure that this would be suitable for coal burning.

 

[worms]

The only difference between a wood only and a multi-fuel stove is the fire grate and riddle mechanism + ash can.

Yes, that's about the size of it. Although you also need bottom ventilation (don't we all ?) If the only air vents are the top "air wash" ones, I'm not sure that this would be suitable for coal burning.

Ah! That explains it! I was keeping quiet, since I sometimes put peat and coal in the woodburner, with no apparent problems. But it does have its air inlet below the door and hence under the grate. It could do with a riddle mechanism, but nothing that a poker won't solve.