Installing multi-fuel stove advice needed

foundationsmcr

Hi people, I posted this in the DIY forum and it's been suggested I may find more help here;

I’m looking for some advice, but some background info first. We’re replacing a gas effect fire with a multi-fuel burner (burning wood and smokeless fuel) in a detached, stone built Victorian house with a large fireplace and chimney breast. It will be a 4.9Kw burner only used to heat the room it’s fitted in and it’s on an end gable wall in a detached house. The chimney stack is at least 11 meters high.

The options I’ve been presented with from various quotes have left me wondering, can anyone give their opinion on the following;

I’ve been told to insulate the liner because condensation will form on the outside and run down potentially causing damage.
I’ve been told to avoid fireboard in the hearth as it becomes unstuck over time.
I’ve been told to choose a metal/fireboard register plate
I’ve been told there’s no real advantage to 904 grade liners as long as you sweep it regularly.

Fireboard or metal register plate and reasons/benefits why
Fireboard or fireproof render on the hearth and reasons/benefits why (we might just leave bare stone)
Chimney flue liner insultation or not and reasons/benefits why
316 or 904 grade liner and reasons why

Can anyone help on these 4 points please?

Thanks

aelitaman

I sympathise with you, I am currently in the process of having a multi fuel stove installed and when I was searching for an installer the amount of contradictory advice I got was immense. I finally chose an installer that I felt was honest and it seems to be the case he is.

I pondered over the choice of 316 or 904 as I wanted to know if one or the other was required by law but could not get an answer. So I went for 904 inner and 316 outer it is only £2 per metre dearer than 316/316. The 904 is meant to be higher quality and more resistant to corrosion.
The installer did say that 316/316 would be fine it was my choice to go with the 904/316 and when I told him the price difference he said he would have done the same.

As far as I know you insulate the liner get a better draw of the chimmey makes the stove more efficient, i.e the smoke does not get too cold before it gets to the top of the stack. I have not gone for insulation because the installer when he tested the chimmey said I have a great draw so there will be no problems. Also I like the idea that some residual heat will spread out to the rooms above by warming the chimmey up.

I can not see how condensation can form on the outside, you get condensation when hot gases hit cool objects, the outside of the flue liner is not going to be cold! So I would say you would get evaporation as you are heating the flue up.

I left bare stone after the installer stripped it back, I think it looks the best in an old house.

Greenfires

Quick answers as I'm on my way out to a job!

904 is a different grade of stainless steel and is more resistant to corrosion. It has an element of copper in the recipe. Using smokeless fuels can degrade a 316 liner well within the 10 year period often stated for this type of liner. Boiler stoves using smokeless and slumbering for long periods are particualrly good at killing 316 liners. There are big differences between good liners and cheap liners whatever grade you buy! The stuff on ebay etc is usually pretty rubbish though the price makes it look like a good deal.

Use a metal register plate. Fireboard ones can end up getting soft and crumbling.

My installer friend lines fireplaces using vermiculite sheet - heat proof, makes a very neat finish and can be painted as well. Don't plaster it whatever you do! I don't think any of his have ever come away later on...

Insulating the liner would probably be beneficial for you as it's a tall chimney on an outside wall. It helps keep the liner working well as smoke from whatever you're burning is less likely to condense into sticky deposits on the inside of the liner if it's all nice and warm. You should still ensure that any wood you burn is suitably dry though - I've seen liners completely blocked solid in a matter of months using wet wood and trying to keep the stove in all night.

Liners are not required by law unless the chimney is in danger of leaking. However, they can save a number of problems further down the line - which the installer always ends up getting the blame for - and so many installers won't fit a stove without one. Chimney conditions above a stove and an open fire are totally different - and contrary to popular belief, it's not just the installer trying to make more off the job!

As well as the stove working better, the installation will be much easier to sweep too if a liner is used.

Hope that helps a bit!

Cheers,

Andy

foundationsmcr

That's some really useful info, thanks people.

Andy, I'm most likely going to be burning wood for the most part (aged of course) but oocassionally burn smokeless fuel. We're not going to be moving for at least 10 years, would you recommend the 904/904 option to be sure or not? Roughly speaking, what sort of difference in cost will we see based on the chimney height? Also, are their any particular brands of liner we should avoid. I'm aware "British is best", but are there any British brands which don't stack up, so to speak?

alleycat`

foundationsmcr wrote: »

That's some really useful info, thanks people.

Andy, I'm most likely going to be burning wood for the most part (aged of course) but oocassionally burn smokeless fuel. We're not going to be moving for at least 10 years, would you recommend the 904/904 option to be sure or not? Roughly speaking, what sort of difference in cost will we see based on the chimney height? Also, are their any particular brands of liner we should avoid. I'm aware "British is best", but are there any British brands which don't stack up, so to speak?

One of the installers that used to be on here (not seen him for a while) is crphilips and i'm fairly certain the he uses "specflue" liners.

http://specflue.com/catalogue/product/multifuel-flexible-flue-liner

He is up near Leeds.
There are a couple of other fitters on here on and off too so they may have different views but i know this is what he fits / recommends.

Can't comment directly as my chimney is a system chimney (dunbrik/isokern/ankhi style).

foundationsmcr

That's great, thanks.

Greenfires

That's not strictly true though is it?!

It's really important to get your stove installed safely in accordance with Building Regulations. That doesn't necessarily mean that it must be done by a qualified engineer - as long as it's done properly and then signed off by building control if you do it yourself.