Chimney suggestions please

[CliffordPope]

The other thread on chimney problems prompted me to ask my own question.

We have a solid-fuel range cooker in the kitchen, with an insulated flue running up the outer corner of the house on the inside. At the top just below the roof the flue does a gentle double bend over the top of the gable wall and feeds into an old brick chimney stack on the corner of the house. To get enough draw height a cast iron flue is cemented inside the stack and projects above the top of the bricks by about 2' 6", with a removable cowl on top for annual access from above to rod out the bend lower down.

The rather inelegant iron pipe has a traditional chimney pot stuck over it, a few inches shorter than the pipe, which projects far enough to accommodate the cowl.
Some years ago I cemented a pot into position to hide the pipe, and filled the annular space between the pot and the pipe with cement to stop any water accumulating inthe void.

That was fine for a few years, until recently a crack appeared in the chimney pot and a section of it fell off. I would guess what has happened is that the combination of damp, frost, heat, differential expansion and rust has exerted pressure and cracked the pot.

Now I am wondering what to do:

1) Accept the appearance of the iron pipe, chip off the remains of the pot, and leave it
2) Get a new pot, and try again
3) Get a new pot but leave it loose
4) Cement a new pot firmly at the base, but leave drainage holes

The pot is purely ornamental, hiding the pipe. It plays no part in the draught process, and does not support the cowl.

What would you do?

 

[Feltwell]

Personally, I'd put a new pot on with no fill between it and the iron pipe, cement it in place with flaunching but I'd leave a couple of decent size drainage holes at the base so no water can be trapped. I'd also look for a cowl that overhangs far enough to keep the worst of the weather out of the pot, if the current one doesn't do that.

I'm presuming the gap between the iron pipe and the old flue is already filled.

 

[CliffordPope]

I was sort of coming round to thinking the drainage holes might be best, but possibly hard to achieve adequate cement depth to secure the pot. The pot would have to sit proud of the top of the stack by say 1/2", and then rely for security on perhaps three splodges of mortar. Perhaps I could cement in3 pieces of hose pipe and then pull them out once the mortar has set.

I have had another idea of increasing the height of stack, but that would still leave the problem of draining the inevitable water ingress, matching the bricks,and leaving a rather odd brick projecting course half way up. Also I'd be worried about the extra height and weight carried on the rubble wall.

Finding another or modifying the cowl is a good idea. The beauty of the present one is a tight but not too tight fit on top of the pipe. I don't want to be fumbling around with a screwdriver and giant jubilee clip at the top of a ladder.

 

[Abi Cott]

Cement and flauching ain't my strong point, but water will find a way. Hosepipe seems the wrong dimension. All you need is a slit. A frame spacer pre prepared with a genourous dose of washing up liquid sounds fine. In fact possibly more efficient for water egress

 

[Feltwell]

Or - take your new pot and cut a few slots in the base, a diamond disc in an angle grinder will do it easily without breaking it. Slots need to be wide enough so debris won't block them easily.


Then sit & flaunch the pot on as usual.

 

[CliffordPope]

Many thanks.
Cutting a V sounds the best idea.