Benzine
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| posted on 5/5/22 at 06:16 PM |
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Woodburner. Back boiler?
I have a woodburner, it's not the best. Anyway, now that we're screwed with energy costs I'm looking at options for heating. I have a
free supply of wood from work (joinery, and clearing building sites of trees and lots of pallets). I'd like to make use of it instead of paying a
billion pounds a month for gas.
I've built a few woodstoves before and one had a copper coil arrangement that kept a large tea urn bubbling away nicely. I'm thinking of
doing similar but this time run a couple of radiators. One in the hall (wall behind the stove) and one in the landing above.
Anyone hear running a back boiler? Or even another arrangement e.g. ducting warm air rather than using water?
On a side note why do stoves have firebrick? To prevent rapid heating of cast iron? I've made stoves from welded sheet steel (6mm) and the heat
from a couple of logs would absolutely belt out compared to a cast iron one lined with firebricks
[Edited on 5-5-2022 by Benzine]
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ianhurley20
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| posted on 5/5/22 at 08:50 PM |
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Not sure of the details but a friend has a wood burner with a 'clip on' rear boiler, will do hot watewer and about 3 radiators. He was
telling me he was going to replace the 'clip on' one with a 'wrap around' boiler so the whole house + hot water will be covered.
No, I don't know the proper deatails but what he has has worked for the last two years and the wrap around boiler is this summers project 
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James
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| posted on 5/5/22 at 11:44 PM |
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Friend of mind has a log burner with a back boiler.
He has a Megaflow-type pressurised heating system with 3 coils in the tank. One of these coils is connected to the back boiler so he can heat his
water with it if he wishes.
Might be worth investigating.
Just as an aside, a 2nd coil is connected to the solar-hot roof system. Im not sure about the 3rd!
Let us know how you get on!
Cheers!
James
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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jps
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| posted on 6/5/22 at 06:23 AM |
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To share my experience, which is of ‘things we’d do differently next time’!
We have a wood burner with back boiler, it connects into the sealed/combi boiler central heating via a heat exchanger and a manifold system with a
electronic box of tricks that shuts down the combi when the wood burner gets up to temperature. It’s a good idea in principle but in practice more
faff to operate and I would not bother doing it again.
Also in order to get the appropriate boiler Kw output to heat all the radiators we’ve ended up with a wood burner probably too big for the room it’s
in, so the room can easily get too hot (especially given I’m in the SouthEast and we’ve not really had a cold snap since it all went in, 7 years ago!
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Mr Whippy
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| posted on 6/5/22 at 06:28 AM |
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This is how I heat my house in the winter, I use electric panel heaters in the summer. Mine heats 8 radiators, has a good oven and a large hob and
also heats the water tank.
It takes a lot of wood to heat a house, pine and other low density woods just vanish so best to use a dense wood like oak. Don't forget about the
cost of the chimney, it was half the cost of the installation for me as it has to be about half a meter above the ridge line of the roof and my house
is 1 1 ½ stories. Also very important is cleaning the chimney so think about access and all the mess during cleaning related to that.
I bought a large stove/oven combination, it was quite expensive but well built, but the construction is just simple welded plate. I could literally
have made my own if I had a plasma cutter. The fire bricks are there to I think protect the metal from erosion from the fire and are considered
expendable as it the grate. They are not expensive and I'd recommend them. The water boiler part of the stove is 10mm steel plate made into a box
that covers 2 sides with water connections at the top and bottom. I'd not use copper for any parts exposed to the fire.
It's worth reading up on the regulations, there not complex but there is quite a bit of good practice about things like flue installation (how
not to set your roof on fire) and how to protect your system if the power goes down (like a gravity fed radiator that doesn't need a pump and
stops the boiler overheating).
I did all the installation myself including the plumbing (copper) which was quite a bit of work but I'm very happy with it overall but it did
cost me twice as much as expected but will last decades and easily pays itself off over a few years.
[Edited on 6/5/22 by Mr Whippy]
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Stuart Walker
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| posted on 6/5/22 at 07:18 AM |
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We have a complicated system with a gas fire back boiler and a wood stove back boiler which can both theoretically supply the hot water (put in by
previous owner). As jps says in practice I've found that in order to have the radiators reasonably warm you have to really be going for it with
the stove, which means the living room is way too hot. However I think that's because ours is connected to the whole heating system. I reckon if
you were just heating a couple of radiators it would work nicely.
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Benzine
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| posted on 6/5/22 at 07:27 AM |
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quote:
Originally posted by Mr Whippy
This is how I heat my house in the winter, I use electric panel heaters in the summer. Mine heats 8 radiators, has a good oven and a large hob and
also heats the water tank.
It takes a lot of wood to heat a house, pine and other low density woods just vanish so best to use a dense wood like oak. Don't forget about the
cost of the chimney, it was half the cost of the installation for me as it has to be about half a meter above the ridge line of the roof and my house
is 1 1 ½ stories. Also very important is cleaning the chimney so think about access and all the mess during cleaning related to that.
Sounds like a nice setup! I already have a really nice flue installed. Goes way above the roof line, the draw will take your house slippers off. Most
of the wood I get is offcuts of sapele and oak, with some soft woods. Sapele burns amazingly and smells sweet too.
Some people have mentioned the room with the burner getting too hot. Maybe I should make a boiler shed outside and pipe the hot water in, and run a
steam generator for my leccy too 
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jps
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| posted on 6/5/22 at 11:59 AM |
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quote:
Originally posted by Benzine
quote:
Originally posted by Mr Whippy
This is how I heat my house in the winter, I use electric panel heaters in the summer. Mine heats 8 radiators, has a good oven and a large hob and
also heats the water tank.
It takes a lot of wood to heat a house, pine and other low density woods just vanish so best to use a dense wood like oak. Don't forget about the
cost of the chimney, it was half the cost of the installation for me as it has to be about half a meter above the ridge line of the roof and my house
is 1 1 ½ stories. Also very important is cleaning the chimney so think about access and all the mess during cleaning related to that.
Sounds like a nice setup! I already have a really nice flue installed. Goes way above the roof line, the draw will take your house slippers off. Most
of the wood I get is offcuts of sapele and oak, with some soft woods. Sapele burns amazingly and smells sweet too.
Some people have mentioned the room with the burner getting too hot. Maybe I should make a boiler shed outside and pipe the hot water in, and run a
steam generator for my leccy too
My brother in law has an external boiler room with a massive water tank (well over 6ft tall) so it holds heat over several days. Some commitment
though to put all that in !
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dmac
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| posted on 6/5/22 at 01:29 PM |
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I've got a multifuel stove which will take coal as well as wood, it has a wraparound boiler that heats 7 radiators and provides hot water. we run
it on coal in the winter as wood just disappears when the weather is cold as Mr Whippy said. The wraparound boiler keeps the outer skin temp down
which seems to stop the room with the stove from overheating but that could be because the room faces into the westerly wind. Wood is more useful in
the summer as it starts to produce heat quicker and can be lit just for a couple of hours in the evening.
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Benzine
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| posted on 8/10/22 at 05:15 PM |
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In true locost fashion I've done the absolute minimum at no cost. No rads or anything yet, but I've taken the coal grate out of my stove.
After downloading my stove manual it turns out the multifuel stove is almost identical to the woodburner stove, only difference is the multi fuel has
the grate turntable mechanism. Hole blanked off. Also the wood burner has 2 extra firebricks low down thin the area that houses the ashpan in the
multifuel version.
Anyway, I can now fit bigger bits of wood in and more of it so I can get an overnight burn if needed. And getting the heat to other areas... leaving
doors open. Thankfully the location of the stove is so central that it's output can get to 75% of the house if doors are open. Just can't
reach the kitchen.
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