Woodburning boiler recommendation

[Jonathan]

My grandmother is thinking of having a woodburning boiler installed. The idea being that this will (a) give a safe fire that can be opened at will to reveal an open fire and (b) heat dhw & ch to supplement her existing oil burner. I've had a look around but most woodburners seem to be just that, woodburners or room heaters. Many of these can have heat exchangers fitted to provide heat to water. My parents have a dedicated woodburning boiler. Swedish design but 25-30 years old and the makers long defunct. Superb and still going very strong. Basically a steel tank filled with water which is connected into the plumbing. Inside the steel tank is a firebox with flue, riddling, ash removal arrangements and a glass front door. Does anyone know of a similar decent product that is available today?

Also, any pratfalls or other recommendations that we should be aware (or beware) of? Also considering a Dunsley neutraliser but don't know if this is neccessary. Spark arrestor at top of flue. Good or bad idea and insurance implications. The property concerned is thatched. Thanks Jonny

[tom.harrigan]

If I was fitting a woodburning stove with boiler, I would fit one from this company:

for integrating it with an existing oil boiler, I think it can get a bit complicated unless your HW tank or new thermal store is sited approximately above the stove. I like thermal stores because you can heat the store directly with an uncontrolled source, and therefore need only one feed+expansion tank. Opening a stove to reveal an open fire is a bad idea, best get one with glass door. If the cost or complexity of combining the two heat sources puts you off, a space heating stove can still save plenty of oil!

Tom

[Gordon Henderson]

We've got one of these:

are planning on getting a 2nd one, possibly next year with the back-boiler fitted to replace the gas boiler we have.

How efficient it will be at heating the water, as well as the room is a factor to be considered, and it might be that a dedicated one for purely heating water might be more efficient - but I have to say the one we currently have gets our living room seriously hot, and it has a 12' high ceiling too, so I'm sure theres plenty of heat to spare...

I doubt you'd need a spark arrestor - the flue from our current stove does not go dirrectly up the chimney - it's diverted over the top and back into the stove where it pre-heats the incoming air, although the people who installed out stove did fit a "UFO Cowl" to the top of the stack, but I got the impression it was more to do with stopping rain than anything else.

And do make sure you have a good supply of well seasoned wood! Burning new wood is a sure fire-way to really gum up the works...

Stovax are based in Exeter - so the road miles it has to travel might be a factor - but since we're in Devon anyway, it's good to buy local, so have a look where you live - there's bound to be plenty of showrooms, etc. as woodburning seems to be coming back into fashion... (although it never went away where I live though!)

And theres always the navitron site for more info:

[robgraham]

I have just the set up your grandmother is thinking of. However you cannot use a woodburning stove just to heat the water feed to the oil burner, they have to be blended (can't think of a better term).

What is required is a Dunsley Neutraliser

allows two or more sources of heat to be linked together without any crosslinking between the sources. It is basically a little tank at atmospheric pressure which all the heat inputs and outputs join - it is a bit of a plumber's nightmare. I have seen it said that it could be thought of as a miniature thermal store - not much storage but it is effectively a directly heated tank.

The feed from the woodburner will be gravity and that from the oil burner pumped, this being seperate from the CH pump.

Please come back if you have any more questions - I can proabably supply sketches from my archives! It is also possible to arrange that the oil burner is off when the woodburner is hot.

The one word of caution is the amount of effort that a woodburner involves - apart from the fetching in of the logs, to get the best out of them they should be stored dry for a full year. At 65 I am still processing my own logs (a beech tree fell conveniently nearby this last winter), but there will become a time when I will have to buy in and then I will still faced with stacking them in the store.

I haven't looked at their web site in detail but my stove is from Woodwarm.

I live near Edinburgh and there is a very good shop their for wood burners, and I'm sure that most big towns will be the same.

In summary, make sure your gran is aware of how much such an installation is going to cost and how much work is required to keep such a stove going.

Rob