Wood burner on to an internal wall

[RrogerD]

I or rather the wife, wants to put a wood burner in where the previous gas fire was, on an internal wall. What's the solution? Can it be done? We have an external chimney about a metre and a half away, outside of the the corner of the room.

My research thus far says that of course anything can be done but with varying degrees of hassle, mainly wrt compliance with Part J of the Bldg Regs.

Can I run the flue diagonally up the inside of the internal wall, to the chimney? How important is it in having the space around the unit? And the size of the hearth?

Any thoughts? TIA

 

[foxhole]

The gas fire has a flue ? To where?

 

[RrogerD]

The gas fire has a flue ? To where?

It runs diagonally from what I can make out, up the inside of the internal stud wall (the one it is sat on) to the left-hand corner. Behind this corner, on the outside, is the chimney.
I think that originally from looking at the others in the close, there was an open fire on the left wall and the dividing wall (with current gas fire) was not there.

 

[foxhole]

You could get a hetas engineer to take a look, a corner fireplace may be an option .

 

[RrogerD]

Yep, we've done that. Didn't really get much confidence in the answers where one said "yeah, no problem" and another, "oh dear, I don't think that it could be done".

We were thinking of a corner one and having the telly wall-mounted above the fireplace but I think that it'd look messy, unless we do away with the current fireplace altogether. Also, I wonder if it being a bit close to the curtains, may be an issue.

We've got the burner, a little one that ideally would just slot into / sit slightly proud of the existing metal fire-back. The trouble is, I think that the distance from front of burner to front of hearth is smaller than ideal and, the angle and number of turns to the corner chimney may not be doable.

We thought about a dual-skin flue running up the inside of the wall and up through the room above, into the loft and out through the roof but with required spacing to combustables etc, would be a major undertaking plus, bloomin' ugly having the flue poking out of the roof at the correct height.

 

[StephenStephen]

Having the burner on an internal wall - you keep a lot more of the heat in the building. I'd be tempted to look at putting the burner where the current gas fire is, run the flue straight up in a rigid black flue, and then running it diagonally to the chimney in the room above...

 

[RrogerD]

Having the burner on an internal wall - you keep a lot more of the heat in the building. I'd be tempted to look at putting the burner where the current gas fire is, run the flue straight up in a rigid black flue, and then running it diagonally to the chimney in the room above...

I certainly like the sound of that. Although it may have to be in the loft that it runs diagonally to the chimney. I don't think that the ground and first floor walls align.

Do you happen to know what the minimum wall width would need to be to have the flue running inside of it? Also, I guess that I'd be losing the integrity of the stud wall having it 'split' by the flue. It then essentially becomes two walls, albeit joined together with plasterboard or I assume, hardibacker. Presumably with hardibacker or some other fire-retardent material, there doesn't in fact need to be a gap between the wall faces and the flue? Although I guess that the walls either side may get rather warm.

 

[cdbe]

Have a look on the twinwall flue makers (eg seldek) websites to give you ideas of what's possible. Don't fixate on using the existing chimney (depending on condition etc it could be more bother than its worth). A twinwall could possibly go diagonally in front of the studwall, possibly boxed in to form an alcove below. I don't know what's in the other side of the external wall but it could go through and straight up to avoid going through the roof.

As for the hearth, this whole project is a messy job that will cost you thousands so if that's a worry for you I wouldn't bother.

 

[RrogerD]

Have a look on the twinwall flue makers (eg seldek) websites to give you ideas of what's possible. Don't fixate on using the existing chimney (depending on condition etc it could be more bother than its worth). A twinwall could possibly go diagonally in front of the studwall, possibly boxed in to form an alcove below. I don't know what's in the other side of the external wall but it could go through and straight up to avoid going through the roof.

As for the hearth, this whole project is a messy job that will cost you thousands so if that's a worry for you I wouldn't bother.

View attachment 211892

I like your suggestion, thanks. The house is only a 1980's Bovis construction. The external chimney appears to be satisfactory. All of the other properties in the close appear to have retained it's use for an open fire.

The alignment that you suggest, I had thought of, although I was going to imbed within the wall but, I think that I may struggle with maintaining the 45deg bends and it hitting the external wall before hitting the ceiling. It obviously gets even messier if we have to go through the ceiling at an angle and try and avoid ceiling joists etc.

The stud wall is 375mm face-to-face. I assume, with 12mm plasterboard and 75mm stud timber, this leaves 200mm for a gas flue. Sufficient, but I assume too tight for any solid-fuel flue? Especially a twinwall type?

 

[lostinthelight]

The minimum clearance on the best twin wall is 50mm so you have to add 100 mm to the od of the flue you use to get the required distance between combustables.
When shopping for flue, watch out as some say 50mm clearance but it can be more than that if boxed in and not ventilated so check the specs or ask to be sure.

 

[RrogerD]

The minimum clearance on the best twin wall is 50mm so you have to add 100 mm to the od of the flue you use to get the required distance between combustables.
When shopping for flue, watch out as some say 50mm clearance but it can be more than that if boxed in and not ventilated so check the specs or ask to be sure.

Is the 50mm to combustables? In other words if I use hardi-backer, could this clearance be reduced?
What clearance would be needed, to combustables or other, for non-twinwall?

I'm thinking, if I strip back the rear of the stud partition wall then I could simply include the clearance, new flue, new clearance and then re-build the studs and plasterboard. 375mm wall becomes 485mm thick wall.

 

[RrogerD]

Is the 50mm to combustables? In other words if I use hardi-backer, could this clearance be reduced?
What clearance would be needed, to combustables or other, for non-twinwall?

I'm thinking, if I strip back the rear of the stud partition wall then I could simply include the clearance, new flue, new clearance and then re-build the studs and plasterboard. 375mm wall becomes 485mm thick wall.

Edit: https://www.glowing-embers.co.uk/blog/distance-to-combustibles/ says There is no regulation for the distance of Twin Wall flue pipes to a non-combustible material whilst for a non-twinwall it would be 1.5x the dia of the flue.

Also, as you say when boxed-in the clearance distance is greater, up to 80mm or so.

 

[lostinthelight]

If hardiebacker is fixed to a combustible stud wall I dont believe its then classed as a non combustable wall.
Ive recently installed two flues using Selkirk stc twin wall and while expensive it can be fitted with 50mm air gap and same distance if boxing has air vent low and high in the same room

 

[RrogerD]

If hardiebacker is fixed to a combustible stud wall I dont believe its then classed as a non combustable wall.
Ive recently installed two flues using Selkirk stc twin wall and while expensive it can be fitted with 50mm air gap and same distance if boxing has air vent low and high in the same room

Now that's an idea with the vents. I presume with the hot pipe it will self circulate and therefore vent?
Many thanks for that.