Not just which boiler, which whole system should I get?

[max_lan]

I have an old bungalow with poor insulation. And a lot of external walls.

My existing 37kw W Bosch combi boiler has just failed on me. About 6 months before I was planning on replacing it...

I also have an old wood burner needs replacing too.

Is there a system I can get that will let me pipe in a back boiler from a wood burner to boost the heating and still be pressurised from the mains water?

(I have space for a tank if it needs one)

I don't use a lot of hot water but due to the house layout, I do use a lot of heating. I work from home most days and keep the work room warm with the wood burner but would like to spread that heat around a bit. I'd rather not use fans and ducting because they're noisy.

Because it's a bungalow, I don't really want a low pressure system because the pressure will be tiny. (Without spending loads of money on pumps)

 

[muggles]

It is possible to have a wood burning stove on a sealed system, and there are a few on the market approved for this, but it gets quite complicated and expensive. You need someone who holds both dry & wet supplied fuel appliance qualifications, and who also has the skills & experience necessary to do it safely. That's a very very small number of installers. I satisfied two of those three requirements until recently, but never actually fitted one. I know you need a permanent mains cold water supply to be connected via a quenching valve which will quickly cool everything down if it overheats.

Your best option if you do want to do this would be a combination thermal store, and keep the stove on its own low pressure system. This will give you mains pressure hot water and a sealed heating system whilst keeping the solid fuel side open vented, which is much safer. Still expensive though - I've recently installed such a system just before my qualifications ran out and the thermal store alone cost £2400 to buy.

In reality I'd recommend a small 3-4kW dry stove for the one room you want to heat that way, and a separate boiler & radiator system to heat the rest of the house. Wood is more expensive per kWh than gas and the installation costs quickly get to be very high if you're doing it properly. For a fully integrated system with a new boiler, new woodburning stove & flue system, thermal store, and the kit that goes with it you can easily spend £15-20k. On top of that, thermal stores knock down the efficiency of modern condensing boilers as they have to be run too hot to condense, to maintain the temperature of the store.

 

[oldbutnotdead]

Unless you get wood free you'll just be increasing your heating costs, even with free wood the install costs will take many years to recover from lower utility bills.
@muggles has outlined the system I have (open vent woodburner and gas boiler linked to thermal store, plate heat exchanger for mains pressure hot water)- it works well but stoking the woodburner to keep up with the thermal load in winter is almost a full time job- with hindsight I'd have put a bigger store in but there we go.
You will be better spending the money on insulating the place and just have a dry burner in your working room.

 

[Nige F]

Have you looked at wood pellet boilers ?