What to use to insulate a SS flue liner?

mariat

After years of putting it off, we have finally splashed out on a 6.5kw woodburner. As our house is nearly 200 years old, I know the flue needs to be lined, also it draws very badly. I am waiting for some more quotes from Hetas installers, but the first one I got was for £2100! So I am pricing up materials for a DIY job (I know it will need Building control approval and the hire of some form of access equipment). My question is, what can I use to insulate the liner? The bottom half of the flue is very wide, so I think using vermiculite etc is out. Also, I read it should be mixed with cement, but then what happens if the liner ever needs to be replaced? 316 grade liners only have a 10 year guarantee. The other option is a liner jacket, like Chimwrap, but at around £20 for a one meter length, it seems very expensive for what it is (my flue is about 9m high). So I am wondering if there is an alternative to these? I'd be grateful for any ideas.

muckybutt

There is concrete lining which can also be used, what happens is a large inflatible rubber sock is fed down the chimney, then its inflated and a slurry concrete / vermiculite mix is pumped down, that goes off sock deflated and hey presto a lined chimney, look for concrete chimney lining specialists

mariat

Thanks MB, but I think that would be out of my price range. Just had another quote tonight for £1650, so I think we'll be DIYing it. But would still like to know if there's an alternative insulation we can use. Or does anyone know of a cheap supply of vermiculite?

Flyfisher_2

904 grade multi fuel chimney liners have a 20 year guarantee, but are usually twice the price of the 316 grade liners, it would probably be around £500 for nine meters.

mariat

Hi Flyfisher - £289.80 to be exact:rolleyes:

But can no one tell me about insulation?

E2A - After a lot of searching, I found out today that my local Travis Perkins sells 100L of Vermiculite insulation for £8.50+Vat, about £6 a bag cheaper than the cheapest online flue supplier.

Now I need to find a scaffolding company, or cheap cherry picker hire. Problems problems LOL

Flyfisher_2

Can I ask why do you need to insulate the flue pipe if it is going inside a masonry chimney? In over 20 years in the building trade the only place on a chimney I have seen Vermiculite insulation used was behind fire backs on open coal and wood fires or where there was any combustible material nearby.

beetlebum_2

I know I didn't bother with any insulation when I installed my liner. Some people say you should, others say it doesn't need to be done. I also installed a 316/904 liner which cost around £25 per metre. You only really need a 904 liner if you intend to burn smokeless fuels, but I thought I'd cover all eventualities.

mariat

Our fireplace is a big old inglenook, and the flue itself is very wide. A flue fitter who surveyed it yesterday reckons it could take as many as 15 x 100L sacks of vermiculite, where as they normally take around 6. The reason we bought the woodburner was that an open fire just would not draw, the room filled with smoke no matter what we tried, even with a hood and register plate fitted. It's also on an outside wall which is exposed to the prevailing winds. So, insulation will keep the flue gases hot and improve the draw. Without it, the gases can condense and cause damage to the flue, and water seepage back into the woodburner. It also stops heat escaping through the register plate and through the outside wall.

jonzeyboy44

Hi I am in the process of having a stove fitted. Due to it being a modern house i am having a chimney built of brick construction any one tell me what height the chimney needs to go to. Our roof does not have a conventional gable end but a sort of dutch barn type. The building regs are quite complicated. Any help would be great

fluesystems

Hi. There are many differing opinions regarding the use of insulation with chimney liner installations. Some insist on it, others insist on not using it. In our experience, the majority of installations do not need additional insulation. The air between the liner the the stack warms and act as insulation itself. We recommend only using additional insulation where the stack is either very high, very large or external in an extremely exposed position.

If you are going to insulate, then there are 3 options, micafil (or vermiculite), chimney liner insulation jackets (these are foile backed Rockwool sleeve 1 metre in length), or Chimwrap. We agree that a Micafil cement insulation is going to be messy to remove in the future, so think carefully before deciding.

Micafil will seem expensive online from us and all chimney products suppliers, as much of the cost will be in the transportation. You will save money if you can collect it from us , or a builders mechant.