Chimney lining, is it worth shelling out double the money ££ for 904 grade stainless steel chimney liner?
The stove industry is in full swing and most installers and showrooms will want you to install a chimney lining / liner, we are not about to go into ‘why’ here, but we will discuss the options.
Firstly what’s a liner?
It’s a flexible stainless steel metal tube or ceramic liner thats inserted within a masonry chimney
Are there different types of liner?
Yes quite few:
- Stainless steel flexible liners 316 and 904 grade.
- Ceramic liners, these can be clay, pumice as well as formable ceramic liners.
- Rigid stainless steel pipe e.g. prima smooth by Schiedel.
Whilst having all these types of chimney liner available, most people still opt for the flexible steel liner. This is mainly due to cost and the lack of experience installing other liners, a small length of chimney liner can in most cases be fitted within a day for a few chaps, where a ceramic liner can require allot more work to reline a conventional masonry chimney, this is due to the bends involved within the chimney. Typically when installing a masonry liner like pumice or clay, the original chimney is chased, this is where you cut pockets or remove lengths of wall to fit the new lining, as you can imaging this involves allot of work as well as mess.
So why are there 2 grades of flexible liner?
The theory is that 316 grade stainless steel is less resistant to soot and tar deposits than the superior 904 grade stainless steel. This is of course true but does it matter?
Most manufacturers will say if you are going to slumber burn (to load fuel into a stove and let it smoulder away), then a 904 is better suited due to its superior ability to deal with tar and creosote or you’re going to burn coal or coal based derivatives. We would argue that you should not be slumber burning at all, as it simply creates tar and creosote within the chimney then goes on fire, not to mention the pollution caused by slumber burning or burning coal products.
Most liners are destroyed by high temperature and having a superior grade in our experience does not make any difference.
These high temperatures are generally caused by chimney fires, which can reach in excess of 1000 deg c this causes the liner to virtually disintegrate at the hottest point or distort the liner, making it un-usable.
Another way metal liners are damaged is by using a liner to close to the stove, we typically always use 1mm solid stainless for around 1 m from the top of the appliance, this means any flame drawn up on windy days does not touch the liner meaning it does not get as hot and therefor extends its service life.
We have many customers who think they know best and want 904 grade liner, after all “it’s the best”. Then they burn wet wood, don’t sweep the chimney less than two times per year, then have a monster chimney fire and sadly the liner is damaged. Regardless of the grade of stainless steel liners it won’t put up with abuse and lack of maintenance.
What's the price difference
That depends on the manufacturer but with most liner manufacturers it’s around double the cost for a 904 liner opposed to a 316 grade liner.
What's the guarantee difference
316 grade stainless can generally have up to 20 years guarantee, while 904 grade can have up to 25 years. Whether they will be honoured in 20 years only time will tell. Guarantees generally only include a new liner and not installation, or adaptors etc that are required.
Many manufacturers are now giving a life time guarantee, this means as long as you have the same appliance and installation, then its covered until you remove that install.
So is it worth paying more?
My personnel opinion is no.
I have a 316 grade liner in my own home, going on 10 year plus, with 2 sweeps per year burning dry wood and hard wood briquettes.
If you have a 316 grade liner and its;
- Installed properly
- Well insulated using leca not vermiculite
- Customer burns fuel within the manufacturers guidelines
- Sweeps regularly
- Uses a qualified sweep with proper liner brushes
- A quality liner, all liners are not equal, we only recommend Schiedel tecnoflex, not the cheapest but good quality and well made, much heavier stainless steel than other manufacturers
..you should have a long trouble free experience with your liner.
However, if you want to burn coal, other dirty fuels, slumber burn and hate the planet a 904 grade liner may give you a longer life span.