Extracting heat from woodburner

[dal]

So I'm having a woodburner fitted soon in my lounge, it will sit inside our existing fireplace. Now what I want to do is extract hot air from the fireplace through a 9.5" brick wall into the kitchen (see diagram below) with either 4 or 5" metal ducting.
So I'm thinking I'd need to insulate the ducting to keep the heat in.
The thing is I'm not sure how hot the air is going to be that is coming through the ducting.

Do you think this is viable ?
Would I need a special fan that can handle high temps, any suggestions, the fan only need to run at a low speed ?
Ideally I'd like the fan to be able to fit in the 6" gap between floor and bottom of kitchen unit and be fairly quiet.

measurements are approximate.

https://i.imgur.com/CWeZXBJ.jpg

 

[Usel]

I think you need a circle of air. One pushing hot air in at the top and one pulling cold air back into the fire at the bottom.

 

[joey1211]

I can't see a single fan (guessing it's 5cm at best) is going to pull enough warm air through, again, a 5cm pipe to heat a whole room

 

[Mercenary Keyboard Warrior]

You need to be careful of the rules in regards flammable materials being a certain distance away from the stove, by creating a hole in the rear of the fireplace you are by default (because you are trying to transfer the hot air) bringing items into direct potential contact with the very hot air

 

[DXP55]

My log burner is in the old fireplace hole - When I fitted it I had a steel box made to go in hole first then filled any gaps up between box and brickwork surrounding it with vermiculite - in past I had trouble with material cracking behind and around the fire.

Once it was up and running I soon found that the wall on the other side was getting quite hot to touch - If that had been in the kitchen it would have been like a storage heater. - Only problem I had was the bookcase is there.

What I ended up doing was put a sheet of steel inside box on back with gap of 2" at top and bottom and spaced out from back of box by about 1" - the heat then heated plate up and wall at back was cooler - Next step was to put a vent hole through box and wall just above skirting - this in effect created a draft into the fireplace so creating a shift of air around the steel plate - Not only did it keep wall cool it also threw out more heat from convection.

The purpose of this is to illustrate how much heat you will have traveling through the wall. Do not under estimate how hot they get - Even now where flu meets the chimney clay liners the wall still gets hot - One other point is will you have tiles on other side of wall or unit's - I don't know how the heat would affect those.

I think I have a better picture somewhere

 

[dal]

I can't see a single fan (guessing it's 5cm at best) is going to pull enough warm air through, again, a 5cm pipe to heat a whole room

No it will be 4 or 5 INCHES not cm which should be able to pull plenty of air through, I think my biggest problem will be finding a fan that can operate at such a high temperature and Also be fairly quiet.

I'm going to see how it goes without the hole / fan to start with maybe with the doors open from kitchen to lounge the kitchen will get enough heat as well

 

[the_r_sole]

I'm no expert in this, but I'd image pulling air low down at the back of a stove to a floor level output is not going to give you great results either way, can you not draw the air from the top/above the stove?
You may also have issues with building control as there are some regs around using woodburners in rooms with extractor fans as it changes the operation of the fire.

 

[dal]

I could extract from just above the stove. I'll have to check up on those regs then. Like I said I might not need to extract at all but our kitchen is always cold in the winter ( unless we are cooking of course ) & it would be a real bonus if we could pull some warm air in from the fireplace

 

[DXP55]

Thinking about again I think the simplest thing to do is put a plinth electric heater in the kitchen - We are like you -There isn't a rad or heater in my kitchen but once the oven goes on it soon warms up due to fan on rear of oven blowing air over it to keep it cool in the eye level housing.

 

[robj20]

No back boiler option for the woodburner and fit a plinth heater. I'm thinking of going this way and piping it into the central heating.

 

[FurryLemon]

You can pump the hot air around the house quite successfully using pipe. I've a friend who heats his house this way (rads still required occasionally though). However, he didn't retrofit it. It was all done when he rebuilt the house from the ground up.

You need a log burner designed for this purpose and a fan to circulate the air.

You should not be contemplating doing this yourself.

You'd save a lot of hassle and money just fitting an electric rad though.

 

[task]

No back boiler option for the woodburner and fit a plinth heater. I'm thinking of going this way and piping it into the central heating.

Back boiler mavity feeding towel rail, however, electric plinth heater will be far cheaper to install.

 

[dal]

You can pump the hot air around the house quite successfully using pipe. I've a friend who heats his house this way (rads still required occasionally though). However, he didn't retrofit it. It was all done when he rebuilt the house from the ground up


You need a log burner designed for this purpose and a fan to circulate the air.

You should not be contemplating doing this yourself.

You'd save a lot of hassle and money just fitting an electric rad though.

I'll have a word with the guys fitting the burner and see what they think, I did speak to one heatas fitter and he said as long as it's metal ducting he couldn't see a problem with it . Like I said i think the biggest problem will be getting a fan that can handle the heat it would suck through. The ducting could be insulated to stop the heat heating up the surrounding area.

Personally I think it would work.