/ Wood Stove/Combi Boiler

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We're thinking of buying and installing a wood burner at home, but figure it would make sense to connect it up to the heating system too, if possible.
Unfortunately, there's not a great deal of info out there on how to connect a wood-burner-back-boiler into a system currently operating a combi boiler. Does anyone have any expereience of installing a system like this?
Also, we've calculated that to heat the room, we need a 5Kw stove, how much larger should I go to allow for the water heating?

Cheers Folks,

CB.
rurp - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC): Not an expert but we have a charnwood mutifuel stove. It is connected to an accumulator tank (basically a big tank of water that it heats up) hot water and heating are drawn from coils that pass through the accumulator. We have a backup lpg boiler so the accumulator never gets too low.

A combi-boiler doesn't have a water tank as you know so I don't think it will be easy.

You would either get a new system in parallel with a hot water tank or get a simple system where your fire connects direct to a couple of radiators. this is not ideal as you want to use the heat from the fire at other times and for hot water.

Our stove does 3kw to the room and 10 to the water. This is enough to heat a three bedroom well insulated house and hot water without lpg etc unless it is below 2degrees.
johncook - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC): Contact the manufacturer of the stove you are thinking of buying. They have been linking systems for many years now. I know that the Charnwood range were making stoves and linking them to gas and oil systems way back in 1980, so they are a good place to start. They may be on the net under the name of Wells Stoves. When I was in the wood/multifuel industry the Wells/Charnwood company was based in the Isle of Wight and had one of the best reputations of any in the business (I didn't work for them I worked for one of their competitors, but knew them well, and was always trying to beat them.) There are many other manufacturers around, but try to find ones with a lond history, as it is an industry where new makers appear, run for a couple of years until the faults in their products begin to show, badly, and they then go bust and restart elsewhere or under a different name.
RCC - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC):
> We're thinking of buying and installing a wood burner at home, but figure it would make sense to connect it up to the heating system too, if possible.

> Also, we've calculated that to heat the room, we need a 5Kw stove, how much larger should I go to allow for the water heating?


Presumably the central heating loop is closed? In which case I think there are regulations about having uncontrolled heat sources connected directly. Possibly it could be done indirectly, but may be more trouble than its worth.

Also, you would be stuck with heating the radiators (or a heat dump) whenever you had the stove on. Depending on how you use your house this might be quite inefficient when you could have a smaller stove comfortably heating just the room you are using.

A cheaper (and more controllable) alternative might be to install vents and fans between rooms so that you can move hot air around directly.
Radioactiveman - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC):

good sites for info/research

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

http://www.thegreenlivingforum.net/forum/
Radioactiveman - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC):

dont forget you need a bloody good supply of cheap wood, that may well need chopping seasoning(up to yr depending on wood)

Also depending on your setup dont expect to come in and the house to be warm in 30 mins time unless you go for a more expensive setup.

Also cost can be prohibitive as you need a higher grade 904 liner ( stove takes more heat out so more plating out of crap due to lower flue temps) You may need a thermal store,extra tanks and controls then installation costs etc

Its a good idea but there is a fair investment and then the wood side of things to consider.

goosebump - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC):

Wowsers, thats a nice big room youve got - 5kW is pretty high. We have a multifuel stove (Woodwarm brand) to heat the whole house, via a thermal store/accumulator tank. Such tanks are usual with stove + radiator installations, since they help balance out the peaks and troughs in heat you get with a stove. We could hook up a regular boiler to the store too (and solar), but havent yet.

There is plenty about this on the internet and you do need to read about in order to sort out heating and hot water in the places you want, when you want.

Last time i looked, it was difficult to use a tank/store as a feed to a combi (using the combi to "top up" the heat if needed), since combis are made for cold water feed only. If this has been resolved, or your combi can take warm water, then that would be the most straightforward approach*

*I am not a plumber and there is almost always a million different options when it comes to plumbing a house. Good luck!


PS If David Hooper were here he would add his tuppence, he loved his Clearview stove.
SteveCarter - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC): Hi, installed Dunsley Yorkshire wood burner stove... still the only wood burning stove you can legally install in a smoke control area(I believe...?)because of it's low emissions(exemption certificate supplied on purchase)... It heats a 10 room house & hot water cylinder... also connected to combo boiler system but can be isolated so combi can run just hot water whilst stove does heating at the same time. Combi can also run heating if needed... never bought any wood/timber over the 5yrs installed, there's oodles of free fuel to be had... but it can gobble the wood a bit when on full tilt. Cost 2k approx including stove/flue/pipework etc... best money saving idea ever.
John_Hat - on 20 Feb 2013
In reply to scarter:

That's interesting, I would be very interested to know how that installation was done and how it works!

J
In reply to John_Hat: me too! any chance of some sort of plumbing diagram?
the power - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC):
> (In reply to John_Hat) me too! any chance of some sort of plumbing diagram?

Google dunsley neutraliser.
SteveCarter - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC): If you google Dunsley Yorkshire wood burner stove there's a plumbing diagram on the Dunsley website... but basically the stove has 4 outlets(28mm) in the rear, 2 at the top & 2 at the bottom... flow at the top, return at the bottom. One from the top goes to the hot water cylinder(vented) in the loft & returns to the bottom... this heats the hot water by thermal convection. The other 2 outlets connect to the existing flow & return on the central heating system but have a gate valve on each so the stove, which is vented & pumped, can be isolated from the existing combi. There are two other gate valves at the combi flow & return so when the stove is in use(8-9 months of the year) the combi can still be pressurized & used for hot water only. To revert to normal combi use for water & heating, close gate valves at stove end to isolate stove then open valves at combi end, check pressure is ok and fire it up. We've only had to do this on a few occasions in the last 5 years when we've ran out of wood... & that was only in the first few winters because we weren't organized with a wood store. Combi supplies hot water to kitchen & one bathroom(bath) 12 months of the year. Hot water cylinder(heated by stove)supplies hot water to 2nd bathroom(shower only) 8-9 months per year. Stove does heating 8-9 months per year. Obviously stove not on in the summer, when heating not needed, so no hot water in cylinder for shower in 2nd bathroom but can be connected to back to combi system by opening a valve.
SteveCarter - on 20 Feb 2013
In reply to carrot_boy (North East Wales MC): ...the pump for the stove side of the system is controlled by two pipe thermostats on stove heating flow & return. If anyone wants any photos of valve set up at combi end or stove end send just send email.
goosebump - on 21 Feb 2013
In reply to scarter:

Obviously Im not the OP but thanks for the full reply. Our system still isnt quite right for us and there's some useful stuff to mull over...
cheers!
John_Hat - on 21 Feb 2013
In reply to scarter:

Thank you!

hmmmmn... goes away looking thoughtful..

Q: How do you control overheating/boiling of the hot water or central heating given the stove is an uncontrolled heat source?

Q2: Presumably this set-up (as I read it?) means the stove has to be fired up and running all the time in winter - including overnight?
Ridge - on 22 Feb 2013
In reply to scarter:
> (In reply to carrot_boy (North East Wales MC))

> never bought any wood/timber over the 5yrs installed, there's oodles of free fuel to be had...

I'm intrigued by this bit. I'd think this would be difficult for most people. Even using scrap wood, (this would probably be easier in built up areas,as in rural areas anything flammabke is immediately scavenged), it'd be almost a full time job collecting and chopping wood on that scale. I'm impressed, (and very jealous)!
SteveCarter - on 22 Feb 2013
In reply to John_Hat: Hi, we've never had a problem controlling the output of the stove. It has a control on the side for the air intake, which if fed from outside, and can be "shut down" manually if need be... this control also has a thermostat which closes air intake automatically(details on Dunsley website)... non of the larger downstairs radiators have any TRV's, and obviously, if you don't need as much heat, don't fed it.
The stove is only running during the day, had on until 10pm last night and house is still warm this morning(17C right now at 8am)... if no-one in through the day it won't be running, at weekends it's on all day... yeah it can be a bit nippy sometimes when we get in on the evening in a sub zero winter but it warms up pretty fast.
It took a couple of years for us to get organized and to work out the most efficient way to use the stove, and all the elements the keep it running, but now it pretty much runs like clockwork. It does involve some work and you don't always get the same even heat throughout the house... upstairs is usually ok but it can vary downstairs... obviously the living room with the stove in being warmer than kitchen/dining room etc
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SteveCarter - on 22 Feb 2013
In reply to Ridge: Hi, yeah I live in urban area(hence the reason for smoke control), I tend to stock up on clean dry timber through the summer and supplement with occasional foraging trips during the winter. Hardwood logs look great and burn for ages but brand new, clean, dry pallets are the best(free)fuel source by far... they burn better and produce more heat and almost zero ash.

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