Insulation behind woodburner

[nwnw]

I'm changing out a wood burner and I want to insulate to the stone wall behind while I have access. I only have about 60-70mm from wall to flue. 

Can anyone advise on best fire board and insulation combo to give best insulation? Is aerogel fit for this purpose? Only 1m2 so cost is not an issue. 

Edited December 15, 2023 by nwnw

[Iceverge]

Would you consider Rockwool batts and moving the stove further forward?

 

Don't know about aerogel. The UK retailer has a phone number. I suspect it'll be prohibitively expensive  for the high temperature panels but keep us posted. 

[nwnw]

10mm 'Spacetherm' aerogel blanket is about £150 for the area I need.  Not cheap, but if it makes the room warmer I'm willing to stomach the price

[Iceverge]

When the stove is up to temp its thermal conductivity will only be the same as PIR . If you could sub 15mm of rockwool you'd be in the same place. 

 

Is it a twinwall flue?

[nwnw]

Lost the thread on this when xmas took over.

Does anyone know if Spacetherm (aerogel blanket) is suitable for this purpose?  By the specs it looks ok for temperature and is fire rated.

 

[nwnw]

On 19/12/2023 at 00:49, Iceverge said:

When the stove is up to temp its thermal conductivity will only be the same as PIR . If you could sub 15mm of rockwool you'd be in the same place. 

 

Is it a twinwall flue?

This doesn't make sense to me.  The U-value of aerogel blanket far exceeds that of rockwool.

[Alan Ambrose]

A stainless sheet might also reflect heat back into the room

[saveasteading]

There are woodburners with back panels to reduce the rear heat.

Then there is the physical gap where air will heat and rise into the room.

I suppose I'm saying leave it exposed.

[Iceverge]

On 12/01/2024 at 15:54, nwnw said:

This doesn't make sense to me.  The U-value of aerogel blanket far exceeds that of rockwool.

 

 

 

Sorry I was a bit off with my calcs. 

 

10mm of a thermal conductivity of 0.0195W/mK will give a U value of 1.95W/m2K. for £150.

 

18mm of Rockwool with a thermal conductivity of 0.035W/mK will also give you a U value of 1.95W/m2K. 

 

You can't buy 18mm though so if you can fit 25mm of rockwool it'll be a U Value of 1.4W/m2K for a cost of £3. 

 

 

 

 

 

 

[nwnw]

Yes, Iceverge you are spot on.  I should have dug into the numbers.  I thought aerogel was supposed to be some wonder material but once manufactured into the blanket form a K value of 0.02 vs 0.034 is Rockwool is not exactly groundbreaking.  I now see why aerogel has not taken off!  Thanks.

[Polish Builder]

You can go for Promat Promafour board but they are very expensive as they are designed for fireplaces and wood burning stoves.

Also using a promat you need to use their filler, glue and it would cost a fortune.

 

 

Personally, I would go for a cheaper option using rockwool ablative coated batt combined with 6mm a1 multipurpose board.

I got it installed 10 years ago and it works well, the board behind the stove is covered with black fire paint.

See below: