Installing double sided wood burner

[Mart]

Hi all,

We have two fireplaces that back on to each other. We'd like to knock through and install a double sided wood burner between the rooms to heat them both.

I'm going to get a HETAS installer involved but wondering how much I can do myself beforehand. I'm sure I could do the current surrounds but not sure if I could go any further.

Presumably there would be two flues (joined by two more for the 1st floor bedrooms) so the installer would need to pick one of them to be the one they line.

 

[paulc]

When I installed my stove, I did all the dirty grunt work and finishing. Just got the HETAS guy to fit a liner & cowl, and make the final connection to the stove. Whilst it cost more than going out and buying the liner myself, it saved on dealing with building control and climbing on the roof. Also had him cap the unused pots while he was up on the roof.
If you haven't already got your stove, I would suggest looking for a model that draws air in through a duct - This will save on having to fit an air vent in the wall (which will be a source of draught and noise). Also go for stainless steel rather than enameled pipe for the initial connection to the stove. Stainless won't rust from the inside like enameled can sometimes do.

 

[Mart]

You've read my mind. I'm keen to do as much of the grunt work as I can to keep the cost down just unsure on how far I can go. i.e. Will i need to get prop supports and add in some internal support for taking out the adjoining back wall and install some further lintels to join them together?

Also agree on getting a burner with a direct air supply

 

[Cubist]

All of the 'two faced' / single fire-box wood burners I've come across have a single flue. Does the model you're considering differ?

 

[Mart]

All of the 'two faced' / single fire-box wood burners I've come across have a single flue. Does the model you're considering differ?

Sorry I should clarify that I mean that there would be two flues currently, one for each fire downstairs. I've counted four pots on the roof so one for each room, they're all sharing the same chimney and I imagine that they all have independent flues, could be wrong in this.

I'm not sure how that would work with a single wood burner having a single flue being centred between the two ground floor flues. Probably something for the installer to work out.

 

[paulc]

You've read my mind. I'm keen to do as much of the grunt work as I can to keep the cost down just unsure on how far I can go. i.e. Will i need to get prop supports and add in some internal support for taking out the adjoining back wall and install some further lintels to join them together?

You won't know if lintels are required until you start knocking things about. One will almost certainly be needed in the middle to support the central wall. You may also need one either side of the opening if it needs to be made bigger. Don't underestimate just how much rubble is going to come out. I had enough to make a shed base when I did mine.
One more comment - Be careful about the choice of wall finished. With my stove lit, I regularly see wall temperatures above it in excess of 120°C (have a sensor embedded in the wall). That rules out the use of gypsum plasters as the stuff will just flake off the wall.

 

[Cubist]

Sorry I should clarify that I mean that there would be two flues currently, one for each fire downstairs. I've counted four pots on the roof so one for each room, they're all sharing the same chimney and I imagine that they all have independent flues, could be wrong in this.

I'm not sure how that would work with a single wood burner having a single flue being centred between the two ground floor flues. Probably something for the installer to work out.

The commonly used flue pipes are around 6 inches in diameter and need a minimum of around 200mm/8 inches clearance within the extant flue. Typically a flexible stainless steel pipe is hauled up to the chimney top by rope and secured there. Only one of the existing chimney flues would be used but, as you will be opening the chimney breast on both sides and installing any required lintels to support the remaining stack, a steel register plate must be installed and the new flexible flue pipe installed through this. Modifications to the first floor flues may or may not be required depending on the nature of any insulation that may be used to surround the new flue pipe and whether those fireplaces will ever be used in the future.

 

[Stevers]

Have held back so far, but I am I the only one who thinks that the front room fireplace is rather lovely as it is? It would be so much easier and less expensive to install the stove in just the dining room fireplace - that looks a bit suspect anyway. If you keep the front fireplace then you have the option of having an open fire for special occasions.

 

[Cubist]

A couple of what may be dumb questions but; do you have the space to store the 15-20 tons of seasoned timber you may consume each year and have you considered the mess that transporting that volume to and from the burner will produce together with the, inevitably larger than one may expect, volumes of dust that will accumulate from its regular operation?

Apologies if I am asking questions you have already considered and accounted for but...... I have come across far too many instances in recent years of some homes installing powerful wood-burners that are seldom used or only fulfils an ornamental function.

 

[malcolm]

My wood store is full with maybe 5 cubic metres (maybe 2.5 tonnes) and I'm hoping that will be more than enough for next winter. Though my wood burners are not a primary heating source. Next winter they might be and the rest of the house will get a bit cold.

Knocking around those chimneys for a single two room wood burner is going to be a fairly serious structural job. I'm not sure how it could be done so you'll get into the nonsense of structural engineers. I would lean towards having a wood burner in each room and £10K left over to spend on the holiday of a lifetime.

 

[paulc]

I would lean towards having a wood burner in each room and £10K left over to spend on the holiday of a lifetime.

Or something like a Stovax Riva with ducts to pump warm air in to the other room ?

 

[Mart]

We had a wood burner in our previous house and used it pretty much daily as supplementary heating when working from home and over the weekend during the winter. We also have much more room to store the wood in our new garden so I have no doubt that we have the space to store the wood and that we will use it. I'd estimate that we'll use between 2.5-3.5m3.

I've had a couple of HETAS installers over and it's looking like approx. £2.5k+whatever I choose to spend on a stove. They would essentially need to clear out both sides and install a steel lintel between both fireplaces.

We do like the fireplace in the living room but this is the one period feature that we are willing to modernise in the name of comfort/efficiency.

 

[mims&pip]

I'm afraid I'm with Stevers on this one....

That living room fireplace is really attractive and worth keeping imho...but then Pip and I are all for retaining original features if they exist

We weren't fortunate enough to inherit any original fireplaces here, so we've added a reclaimed painted, carved timber surround in the dining room (enabling us to put in a wood burner) where there was previously a modern range cooker (it was the previous owners' kitchen) and removed a rusted, condemned 50+ year old oil-fired range from the former dining room (now part of our kitchen).

The latter we replaced with another wood burner in the large opening that had obviously never housed an insert or surround of any kind, dating as it did from the property's days as a working mill.

We had no qualms about removing a hideous modern timber surround and the tiny barrel stove from the former living room.

Although we have oil heating we are very frugal and prefer to rely on the two wood burners to keep us toasty. Fortunately we have our own supply of firewood - when we bought the mill there was a massive (40'+) fallen beech tree in the garden and no sooner had we dispatched that one into logs, a second, even taller one came down over winter 2019/20

Definitely don't underestimate how much timber you'll use in two stoves over the course of a chilly winter!

Mims x

 

[Zebra]

I'm also in favour of retaining it as two fireplaces. If you're only using one room, then you're unnecessarily losing heat to the other one. (Just chipping in on the how-much- firewood -do-you- use question, I use about 2 cubic metres a year.)
I did the entire installation myself - me and my sister did it over a weekend - by involving building control to sign it off, which if I remember correctly, cost £95 for the paperwork. So that side of things you can save a lot of money on if you just read the regulations and follow them. The lintel aspect is harder to comment without more detail. How thick is the wall between?