Green Building Forum - Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

greenfinger — Thu, 15 Apr 2021 15:36:43 +0100

Hi all

Recently had a stove installed.Â We asked for 904/904 flue liner to be used but I'm not sure it has been and am thinking 904/316 might have been used instead.Â The data plate just says 904 on it, and the installer doesn't seem to distinguish between the two.Â Â

I've attached some photos of an offcut that was left...Â Is it possible to tell from these what type it is?Â Happy to take more if that would help.Â Or is there any other way to tell what it is?Â Â

In the third photo you'll see that there are thinner strips of metal that I've peeled back to illustrate the point.Â I don't know if that counts as the inner or whether it is an additional layer?Â But that is definitely thinner than the outer...Â Â

Cheers

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

greenfinger — Thu, 15 Apr 2021 16:15:51 +0100

Photo 1

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

greenfinger — Thu, 15 Apr 2021 16:17:41 +0100

Photo 2

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

greenfinger — Thu, 15 Apr 2021 16:18:31 +0100

Photo 3

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

bxman — Thu, 15 Apr 2021 17:49:24 +0100

If a magnet shows no interest at all it will be 316

which will be the better grade

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

greenfinger — Thu, 15 Apr 2021 18:00:18 +0100

Thanks bxman

I've just tried a magnet and it shows no interest to any of it! Do I need to start to worry?!?

Also, I thought 904 was supposed to be the better grade?

Ta

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

greenfinger — Thu, 15 Apr 2021 18:09:38 +0100

Posted By: greenfingerI've just tried a magnet and it shows no interest to any of it! Do I need to start to worry?!?

Scrap that. I've just googled it and by all accounts 904 is non-magnetic. I was worried for a minute there!

Flue liner identification... Can anyone tell if this is 904/316 or 904/904?

finny — Sat, 17 Apr 2021 11:41:05 +0100

Manufacturers mark should be visible on the outside of the liner.. its often very small and hard to read, but should include the direction of gasses arrow and the grade..
Its only there every metre or so, if you are unlucky and its not visible on your offcut you could give it to an experienced installer as they should be able to feel the difference.. 904 is thicker and stiffer.. or failing that, ask your installer for proof of purchase.. You will obviously have checked your quote to see that you were both on the same page about the liner grade they were installing.
FWIW we never fit mixed grade liners..316 almost always unless the customer specifically asks, or on a boiler stove or where I suspect they may burn coal.. grrr.. or be liable to slumber the stove...double grrr..
A good quality 316 liner, properly installed with good detailing top and bottom, a good stove, good wood and a well educated user should last longer than the customer would expect it to.