Gas stove flue pipe clearance from combustibles

[jordash]

Hi all,

First post and kind of a last resort as I just cannot find the answers on Google after searching A LOT!

I want to buy an Esse 500 Vista gas stove but I cannot find what the regulations are with regards to clearances of combustible materials from the connecting flue pipe.

Basially i purchased my house around 3 years ago and it pretty much had a full refurb and we decided to open up the fire place (it had an inset gas fire before) in the living room to put in either wood/multi fuel stove or a gas stove which looks like a wood burner. We installed a wooden oak beam/lintel and built up the brick around and as we didn't have the cash at the time it's just been left open.

So, now i've come to actually get a stove and I find a plethora of regulations which we should've checked (before opening up the fire place and adding the beam) are stalling the whole thing.

The main issue (after having a stove fitter come and look at the fire place) is that the beam/lintel will be too close to the flue pipe which connects the stove to the flue. Problem is the fitter mainly did wood burner stoves and I don't know if they have different regulations to gas ones.

So, to cut a long story short I just need to know what the required clearance is on a gas stove flue pipe from combustible materials. I found info on the BFCMA guide to flues and chimneys for domestic gas applicances which states that only a 25mm air gap between flue pipe and combustibles is needed, but im not sure if this is gas inset fires only.

Other info I have found states a distance of 3 x whatever the flue pipe diamater is (so around 400mm) but I think that was more for wood burners.

If the clearance required is more than 100mm then it will involve taking out the beam and replacing it with a thinner one (or cutting it down) which is a massive effort. Or getting a flueless stove which I don't want to do, or an electric one which is even worse.

Thanks for any help.

Jordash

 

[muggles]

The regulations are pretty much what it says in the installation manual, which is available on the Esse website.

To summarise: "The gas-fired stove can be installed in any area considered adequate for a solid fuel appliance", ergo the clearances on flue pipe diameter for solid fuel should probably be observed. Maybe more importantly in your case, the sides, back and top of the stove body must all be at least 610mm away from any combustible material, and 50mm (LHS), 100mm (RHS), 75mm (back) and 150mm (top) from non-combustible materials. Can you achieve this? Plasterboard is considered to be combustible, incidentally. The stove is 584mm tall so in practical terms that means that no part of your beam may be closer to the floor than 584+610= 1194mm, or just under four feet

The clearance between flue pipe and combustible materials can be reduced to 50mm if twin-wall insulated flue is used

 

[jordash]

Thanks for swift response Andrew.

From the hearth to the bottom of the beam the distance is 1260mm so that clearance is fine, it was just the clearance of the flue pipe.

The gap which the flue pipe will go into and connect with the flue is only 260mm wide so with the stove being 75mm from the back wall the flue pipe won't have much room at all will be close to the beam. Does that 610mm distance apply to the flue pipe as well?

Is a twin wall insulated flue pipe thicker than a normal one? I think the normal size is 125mm diameter right?

Thanks again

 

[muggles]

I think the implication from the installation instructions is that they want you to comply with the same clearances as for solid fuel. In your case, that means that single-skin flue must be 375mm away from any combustibles.

Twin wall insulated has a larger outside diameter to accommodate the insulation. A 125mm flue will therefore have an outside diameter of approx 190mm, and must clear combustibles by 50mm from the outside edge. It does not need any clearance from non-combustible materials (IE, it can be touching)

 

[jordash]

This is great news, I think the twin wall flue could be a life saver here, thanks Andrew.

I can't understand why the stove fitter who came to look at the fire place didn't even mention this though.

Does this mean that the 50mm air gap is only required for wood burners as well with the twin wall flue? I keep thinking of gas and wood/multi fuel stoves as being different regulation wise.

 

[muggles]

The 50mm air gap does indeed apply to wood burners as well. In general, gas and solid fuel regs are different, but there is some limited overlap

You'll need this http://www.directflues.co.uk/index....category_id=38&option=com_virtuemart&Itemid=7

And this http://www.directflues.co.uk/index....category_id=38&option=com_virtuemart&Itemid=7

Plus an adapter to whatever's going on the top of that straight length

 

[Corgigrouch]

Just a word of caution...Not all twinwall is the same and the airgaps vary, they can be a small as 50mm but some of the really cheap twinwall that I have seen needs 200mm...Check before you buy. I use SFL twinwall and that is good for 50mm

 

[algas]

You could always fix a non combustible strip of cement board or the like to the back of the lintel.

 

[jordash]

Thanks again guys,

just a few follow up questions. The stove i'm looking at requires a 125mm flue pipe, so that means i'll need a twin wall flue with an inner diameter of 125mm, which will make the overall diameter 175mm ish right? Been looking at a Shieldmaster flues so far.

Also can these twin wall flues easily connect to a flexible flue system as I have a normal brick chimney so don't need the whole twin wall flue system, it's just for this beam issue.

Algas, how thick are the cement boards generally and if I stick one of those on the back of the lintel/beam does that mean I don't need the twin wall flue, or I still need the twin wall flue I just don't need to have the 50mm clearance.

Thanks again

 

[algas]

If the board is an asbestos substitute then in theory you would not need any gap at all because it is now incombustible, the boards are approx 10mm thick, the edges would need to be sealed with fire cement. You may find someone who has some offcuts as a whole board would be quite expensive.

 

[Corgigrouch]

If the flue manufacturer make an adaptor from twinwall to flexiliner then the flue can chnge from twinwall to flexi.. If we are still intending to adhere to solid fuel requirements, then the heat proof shield will need a 12mm airgap between the shield and the timber... The airgap between the flue and the shield can then be reduced to 1.5 x the diameter of the flue..

Why are folk so determined to place timber so close to a device that was once designed to burn timber? Sigh