I have to line my chimney with a flue liner. I have pushed the plastic outer liner up through the chimney and need climb up to trim the excess and to fit the "cap" on the top. Do I need to use a scaffold tower to do this? I thought you were not supposed to lean ladders against chimneys in case they would not take the load, but I can't find anything on the internet that says this, so I am wondering if I have dreamt it?
I need to push the inner, steel, liner up the chimney but I thought if I did that and left it poking out for a couple of days whilst I find out about the ladder issue, I wondered whether it might rust? Am I best to wait and push the steel liner up at the last minute or is it quite weather resistant?
Personally, I would have thought that if the chimney can't cope with a ladder and a man leaning against it, then it's in a dangerous condition and needs urgent attention anyway (wind loads in a gale are not insignificant).
I'm expecting to lean a ladder against mine and it's sticking out of the roof by about 3m, so quite tall and dangly. Hadn't crossed my mind as a problem, and now you've mentioned it, I'm still not feeling very worried.
But caution is good... BTW - is this a one or two storey building?
Is it stainless steel? If so it's fine. If not, it's going to rust in service anyway (flue gases contain water, plus rain ingress depending on the cowl on top).
BTW - I'm intrigued about the plastic outer liner - what is this? Wouldn't it melt or are the flue gases not very hot?
Incidentally, how big is this chimney - 1 pot, 2 pot, 8 pot?
Perhaps, thinking about it, a single pot 2m high one might be a bit thin and dodgey, but my 2 pot chimneys are pretty substantial and the 8 pot ones I've seen would probably cope with an elephant sitting on them.
Thanks for the reassurance. Looking out of the window, many people have 10 foot tv aerials bolted to their chimneys, so as you say, they must be quite substantial to support those in the wind.
It's a normal two storey house (ground floor + first floor). It is a single chimney, built for the boiler flue.
It is a balanced flue, so there is the steel liner of smaller diameter inside the plastic liner. The flue gases go up the steel liner. The air that the boiler uses for combustion is sucked down the gap between the plastic and the steel liners IYSWIM.
Because it is a condensing boiler the flue gases are not very hot, so melting is not an issue. Because it is a condensing boiler, there will be condensate on the liner, so you are right, the liner must not susceptible to rust.
However, I am sure there was a conventional flue kit which had just one liner and I have a feeling that was plastic. If so, perhaps the flue gases cool to a safe level before they reach that far (they have to go through metal pieces first) or perhaps the plastic has a high melting point? I honestly don't know.
To answer someone else's post, I think the instructions mentioned dropping the liner rather than pushing it up but there was no mention of anything being mandatory. I suppose that dropping it in has the advantage that gravity is helping you, not working against you. I figured that pushing the liners up reduced the risks of working at height. Six metre liners at the top of a ladder is not for the faint hearted! If I had been cleverer, I might have trimmed the liners to length at the bottom rather than having to do so at the top!
There is a requirement that the steel liner is laid in one direction but as long as it points that way, I can't see that it matters if it goes top down or bottom up.
I know the type - house I grew up in had one of these.
Perhaps be a little cautious then, and don't prop the ladder right against the top? when you first mentioned chimneys, I had my chimneys in my mind, which are very solid.
I think you should wait around for a bit and see if anyone else has an opinion before betting your life on it.
Is it projecting up from one side of the building, because that might offer other means of access (maybe a hireable tower)? How high does it project above the bit of roof its coming through?
Ah, I see. Not come across these. I've been looking at stainless liners for a log burner, so not balanced but potentially very hot.
In theory, if teh boiler is in condensing mode, the gasses must be < 100C.
One of mine is accessible from the top of the dormer flat roof, so that's easy to drop a liner down. The other is pretty much going to have to be done off the top of a 9m ladder.
Interesting stuff, is the liner boiler specific? If so, which boiler.
As another has said, feeding from the top is good for fitting a liner, any strenuous work is done by the person downstairs and the person on top is just there to guide the liner in, so less risk of throwing yourself off balance. You can also, depending on type, pre-assemble the flue terminal to minimise the rooftop work.
Take whatever precautions you can, explore the chimney stack to check it is sound, tie the ladder to the stack and then loop a safety rope from yourself to the stack or to the ladder, not necessarily something that will arrest a serious fall, just something to stop an off balance moment becoming a fall.
This one is but I think there might be generic liners available too. I bought a Grant liner kit to fit to a Grant boiler. I know other plumbers who quoted mentioned buying liners specific to the brand of boiler they wanted to install.
I'm not sure about this. It's still strenuous to carry a 6 metre plus liner to chimney height and the person on the top then has to push it down far enough for the person at the bottom to reach, before the person at the bottom can take over the pulling.
I'll wait for a very still day and then go explore the chimney.
Unroll on ground, attach rope to end. Pull up to chimney after climbing there Drop rope down chimney (with weight) to person #2 Person #2 pulls while you feed up and over.
You should only be guiding and wiggling up top and instructing person #2 when to pull.
Why doesn't it say that in the instructions? That's clearly much easier than someone carrying it over their shoulder up a ladder and pushing it down the chimney, as I had imagined.
Is there a smiley missing from that? I did apply common sense and I pushed it up the chimney so I didn't need any ropes, weights, ladders, or helpers! I've never done it before so I think I did a pretty good job. I can't be expected to know how to do everything first time; that's why I came here to ask and learn.
I've only come across that with pre assembled ss sections of insulated flue for wood fires, normally assembled section by section on an outside wall. The insulation is a fragile foamed mineral cylinder loose between the two ss pipes.
I vaguely gathered that it is necessary to insulate the liner. Presumably to maintain the draught and reduce condensation.
I was curious to know if it can be done without elaborate scaffolding. I suppose the fork lift would reach over the gutter on my roof so handling the liner and insulating sleeve might not be that difficult.
Boiler stoves are now on 16 week delivery times:-(
That's right, for efficiency you want to extract as much heat from the combustion as possible before the flue gases enter the chimney, then you want these gases not to lose temperature in the chimney. Typically the temperature at the bottom will be around 160C and you still want it above the dew point of water and any other vapours at the top, say 120 with a clean burning fire, otherwise the condensate is acidic and can eat ss.
I don't know how straight your chimney is. I must admit I would go for the
904 double skin and simply pour vermiculite or perlite after the register plate is fixed. My reasoning is that where the liner touches the wall of the chimney is insignificant compared with the bits the in contact with a decent width of insulation, I am assuming a 9" (old units) chimney and
150mm liner. This all assumes a good sealing at the register plate and cowl.
Somebody borrowed my roof ladder but, in even older units, the flue is 1 brick x 11/2 bricks so 9"x131/2". For a 150mm liner, this is rather more fill than I care to carry up a ladder:-)
These are Victorian flues constructed in soft red brick and probably intended for some sort of coal burning range. My mother had a small Jotul burning Elm when there were plenty of diseased trees about. There is bound to be a lot of tar condensed and soaked into the brickwork so I am keen to avoid a hot liner touching anything.
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