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

[Oxbow16]

Hi all

 

Recently had a stove installed.  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.  The data plate just says 904 on it, and the installer doesn't seem to distinguish between the two.  

 

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

 

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

 

Cheers

 

 

 

 

 

 

 

[markc]

That looks to be a folded construction which would mean it is the same material inside and out,(this makes it easier and cheaper to produce) if marked 904 then it would be 904/904.

904/316 is made using two separate strips, harder to manufacture but slightly cheaper material for the outer layer. 316 is still marine grade and will not come into contact with flue gases so no problem

 

[Oxbow16]

Thanks @markc

 

There are no markings on the liner itself.  

 

Good point RE the 316, which is presumably on the outside and so doesn't come into contact with the gases.  But with that being said, why do they then manufacture the 904/904 and give it a longer (sometimes lifetime) warranty?  Is it a "second line of defence" situation?  

 

Also, I've just put a magnet to the flue - inside and outside - and it falls straight back off.  Is that to be expected?

 

Cheers

[Oxbow16]

4 minutes ago, Oxbow16 said:

Also, I've just put a magnet to the flue - inside and outside - and it falls straight back off.  Is that to be expected?

 

 

Just googled that myself, and 904 seems to certainly be non-magnetic, so that's a good start...