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Andrew[MG]

Original Poster:

2,833 posts

84 months

[news] 
Monday 22nd October 2012 quote quote all
Does anyone have a system like this? How is it working out for you?

Just doing a little research into it at the moment.

russ_a

1,667 posts

97 months

[news] 
Monday 22nd October 2012 quote quote all
I looked into having one fitted to a combi. A few people on the web have done this but I was unable to find a fitter that would consider this.

I was told that boiler manufactures would not offer any warranty on feeding hot water from a stove boiler back into the pressurised system.

When I was doing my research the Dunsley Boiler Stove with a Dunsley equaliser seemed popular and in the end I had a Dunsley non-boiler stove fitted.

Not sure if this helps at all!

Andrew[MG]

Original Poster:

2,833 posts

84 months

[news] 
Monday 22nd October 2012 quote quote all
Combi boilers have to be one of the most rubbish inventions ever!

Cyder

5,392 posts

106 months

[news] 
Monday 22nd October 2012 quote quote all
We've got one.

It feeds a large 2 stage hot water tank with immersion heaters built into it and runs 6 radiators.

We're quite lucky in that we get loads of wood offcuts from the company the missus works for and find that from cold the wood burner can get the central heating running quicker than the immersion heaters even when they're both switched on (6kW iirc).

The only problem with it really is that it is difficult to keep the wood burner running all night hot enough to keep the water up to temperature so the house is still warm in the morning, so we usually switch back to electrical power overnight but then it's on the cheaper rate.


Paddy_N_Murphy

16,174 posts

70 months

[news] 
Monday 22nd October 2012 quote quote all
I would guess that unless you have surplus wood / fuel, it is not the most economical nor convenient way to heat the House / HW.

Boilers are pretty efficient in comparison.
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DavidY

3,394 posts

170 months

[news] 
Monday 22nd October 2012 quote quote all
You can fit a wood burner with a back boiler to help supply the central heating system. You (should) under current regs have a Dunsley Baker neutraliser fitted to the system as well (last time I looked these were on ridiculous delivery times (4 months). A few things to point out:-

1) The back boiler will suck quite a lot of heat out of the room with the wood-burner so unless you have a big wood-burner, forget it.

2) The back boiler disrupts the airflow in the wood burner, and therefore the clear glass system will not work effectively so the glass with black up.

3) You will burn a lot of wood!!!

I fitted the largest Clearview with a back boiler to a five bed house, this was in the middle room, the living room already had the second largest Clearview in it. The back boiler was used to supplement the central heating system. It did work, but in the winter we were burning a wheel barrow of seasoned wood a day in that Clearview, and a further half wheel barrow in the one in the living room. This was an old 1840 house with solid walls (and re-glazed).

It certainly reduced our dependency on oil (and the associated cost). Due to the pipework arrangement (and a tall tank), it never really got the hot water hot enough for bathing/shower, but certainly got it warm enough for the central heating, So oil was used for about an hour a day to boost the temperature of the hot water. I combined fitting this with a large solar hot water heating array on the roof. The two (solar + Clearview) cost about £8000, and together reduced the fuel bills on the house by about £1200 per year, so the overall payback was quite short.

Hope that helps

David

Cyder

5,392 posts

106 months

[news] 
Monday 22nd October 2012 quote quote all
It does munch its way through a lot of wood!

But then the flip side is that when it's lit the heat it produces for the room/downstairs is instant. And when the log burner is lit in the dining room and the fire is roaring in the living room it's really cosy!

I'm old beyond my years! hehe

BIGMIKE1

328 posts

114 months

[news] 
Monday 22nd October 2012 quote quote all
Andrew[MG] said:
Combi boilers have to be one of the most rubbish inventions ever!
bold statement, usually find people who have experience of old or cheap combi's have these opinions, you also find most people in the trade who don't like them are the ones that struggle to understand how they work and how to fix them! I've worked on thousands and would always put a decent Combi in my house.
As for the op don't think you can connect a wood burner to a sealed system so you'd need to run a second heat exchanger that was open vented and more hassle than it would be worth really

tmk2

654 posts

94 months

[news] 
Monday 22nd October 2012 quote quote all


1) The back boiler will suck quite a lot of heat out of the room with the wood-burner so unless you have a big wood-burner, forget it.

2) The back boiler disrupts the airflow in the wood burner, and therefore the clear glass system will not work effectively so the glass with black up.

3) You will burn a lot of wood!!!

David
[/quote]

The Mrs has one of these in her cottage it heats up the house very quickly, but is a small C18 cottage. The blackening of the glass is annoying. but the stove is only on once or twice a week as it also has an oil fired boiler for the central heating

Andrew[MG]

Original Poster:

2,833 posts

84 months

[news] 
Monday 22nd October 2012 quote quote all
BIGMIKE1 said:
bold statement, usually find people who have experience of old or cheap combi's have these opinions, you also find most people in the trade who don't like them are the ones that struggle to understand how they work and how to fix them! I've worked on thousands and would always put a decent Combi in my house.
There are plenty of threads on PistonHeads about how the making everything other than combis illegal was a big mistake in the UK.

BIGMIKE1 said:
As for the op don't think you can connect a wood burner to a sealed system so you'd need to run a second heat exchanger that was open vented and more hassle than it would be worth really
That's the info I was looking for really. Combi + wood burner sounded nice on theory but I wasn't sure how the system would work.

andy43

3,555 posts

140 months

[news] 
Monday 22nd October 2012 quote quote all
The Dunsley neutraliser is just that - a neutral point.

We have a thermal store, which is a similar 'neutral' idea, into which goes a gas combi boiler (direct), and a woodburning stove (indirect, via a bottom coil, a supposed nominal 10kw to water, 5kw to room).
(We also have a solar upper/middle coil on the store for summer hot water... to be continued...eventually)
Off that store come the pumped and sealed system rads (direct) and ufh (direct).

There is a plate heat exchanger a damn sight bigger than the average combis, with flow switch and shunt pump for the hot water. It'll run two half-decent showers at once, when the store's fully charged.

The actual hot water side of the combi is rarely used, although the system is valved to allow hot water supply from either the store or the combi if the shunt pump were to fail. Works well although the stove does use a lot of wood, it will keep up with rads and supply a bit of hot water, unless absolutely freezing outside, then to be fair it can struggle keeping the house warm enough - then we light a smaller non-boiler stove. Or use the gas smile

An important bit is keeping the wood boiler at the right temperature to burn well - we have a laddomat loading valve that only lets out surplus heat to the store, maintaining the boiler temp at an efficient 78 degrees. Without something along these lines you'll get tarring of the stove and flue, poor burning, more smoke and less heat.

Navitron forum is a good place to start for all this.

It's all major effort - you really need to be aware of the work involved - the stove brochures don't show the mess, the dust, the backache, the woodstore, the log splitter, the state of the car when I've scrounged some wood from somewhere etc etc. I'll use gas every morning, then switch to wood if I'm around all day to run it, using wood most evenings during the winter. Excluding installation costs yikes it has saved money, purely because so far I haven't paid for any wood, but it's more about the warmth and the FIRE. We can get up to a good 30 degrees in our kitchen and an easy 21 around the rest of the house, all for free unless it's below zero outside.

Skodasupercar

664 posts

63 months

[news] 
Monday 22nd October 2012 quote quote all
Running a wood boiler to heat the whole house is a hell of a lot of work.

If you have mains gas then fit an efficient condensing boiler and get a small stove to cold nights/effect.

I have access to a fair amount of wood, and have a wood boiler and central heating in my workshop, and even with the free wood etc I am almost tempted to just stick the fan heater on!!

Rickyy

4,639 posts

105 months

[news] 
Monday 22nd October 2012 quote quote all
Andrew[MG] said:
BIGMIKE1 said:
bold statement, usually find people who have experience of old or cheap combi's have these opinions, you also find most people in the trade who don't like them are the ones that struggle to understand how they work and how to fix them! I've worked on thousands and would always put a decent Combi in my house.
There are plenty of threads on PistonHeads about how the making everything other than combis illegal was a big mistake in the UK.

BIGMIKE1 said:
As for the op don't think you can connect a wood burner to a sealed system so you'd need to run a second heat exchanger that was open vented and more hassle than it would be worth really
That's the info I was looking for really. Combi + wood burner sounded nice on theory but I wasn't sure how the system would work.
You are confusing combi boilers with condensing boilers. It has been illegal to fit a non-condensing boiler since 2005 IIRC (except in extreme circumstances).

I know how to install and repair them, I've also worked on thousands and I still think they are crap!

OP, it will be a huge amount of work to run a back boiler with a combi. I've seen it done before with a conventional boiler, using a twin coil cylinder, but again that is hell of a lot of work for not much gain!

Andrew[MG]

Original Poster:

2,833 posts

84 months

[news] 
Tuesday 23rd October 2012 quote quote all
Thanks for all the great info and experiences guys! It sounds like I'll probably just swap out the gas fire for a normal wood burner in the future. It sounds like a bit of a backwards step but I like a real fire and have always had decent access to free wood.

russ_a

1,667 posts

97 months

[news] 
Tuesday 23rd October 2012 quote quote all
Don't under estimate how much free wood you will need!
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