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Chimney cowl fitting question

S

starbuck

pfm Member
I am going to fit a raincap onto one of our chimney pots because the fireplace on that pot isn't used any more (a C Cap spring loaded type to still let the chimney breathe). As I am going to be up there anyway, I was thinking about fitting a bonnet cowl that I currently have in the garden as an ornament to another chimney pot, which is still in use with an open fire in our dining room (in which we only burn wood). It is the same type as in the following ebay listing:

http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=190913137599

I wonder if anyone has done similar and what effect it has had on chimney draw, if any, and if you encountered any longer term issues with a bonnet cowl in place? I am assuming that gravity does most of the work with regards to keeping the cowl in the chimney pot, with just a sealant required around the edge to keep it snug, though any pointers gratefully received.
 
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You will need to make sure that whatever is on top of your chimney won't be dislodged by the strongest winds it is ever likely to encounter (think along the lines of 100mph or so). A good profiled splodging around with mortar ought to do the trick.
 
yes we have just had similar fitted but the chap used a jubilee clip type fitting which I feel is more secure in high winds
 
Be aware of fire - obviously enough - hazards, it is not unknown for chimneys (or at least whatever has built up inside them) to catch and for flames to shoot out of the top. Whatever you use up there must resist potentially high temperatures, so plumbing sealant type stuff may not be appropriate.

Also, safety first. Be careful with siting/footing of ladders, can you secure them, remember that the chimney itself might be weakened, it could be a fatally long way down if you fall, etc.
 
I made a Chinaman's hat in galv steel for my folks, it worked a treat. Bought ones are ok too but less geometric ally interesting.
 
If the fire works well and you don't have damp problems i'd leave it as a garden ornament.
It might reduce draw in some wind conditions and when (not if) it comes loose and blows off
you'll have a roof / head repair job too.
 
dweezil said:
If the fire works well and you don't have damp problems i'd leave it as a garden ornament.
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Thanks for that, it concurs with a lot of the reading I've been doing since I posted the message. It would be like trying to fix a problem that doesn't really exist for us, as - fingers crossed - we have no damp problems. The house is 140 years old too, so if it was going to be an issue it would have been obvious by now.

The advert says the cowl is only to be used on unused flues.
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There seems to be a bit of conflicting info about them, some people saying they are for unused flues and others saying they reduce down draft and rain ingress but allow fires to still be lit. See here for example (and it isn't the only one I found by any means):

http://www.raygrahams.com/products/121169-chimney-pot-bonnet-insert-spigot-pot-red-180mm.aspx

I wonder if the confusion arises due to them being suitable for use with open fires but not, possibly, with woodburning flues or gas fires? Anyway, not an issue for me now as have decided to leave as is on the used chimneys and stick to the C Cap on the disused one.
 
Got a chimney sweep out today. I meant to watch what he did and went back to do some work-20min later he shows me a bucket of sand , job finished (how far up did you go? All the way up, three storeys). Surprised to see no soot just a bucket of sand. Then the sales pitch- your chimney is rotten and it wll be £3500 to put a liner in and I'm condemning it. No smoke test done. I might be wrong but I can't see how he would have swept a chimney that high in that time with no soot ( it's not been swept in 10yrs and had fires lit a few times every year). What ever work I decide to do it won't be him.
 
That's a very common scam over here also, the liner. However sometimes it is good advice: you just have to find someone trustworthy to give their opinion.

The biggest problem is when chimneys are switched from coal to natural gas (as ours was in the 1970s) that puts a lot more water in the flue, and if it condenses on the inside of the chimney it can cause a lot of damage. We found that when our house was built 100 yrs ago they ran out of liner tiles for the top 10 feet of the chimney and left it unlined, at exactly the point where it most needs a liner. So we had a stainless liner put in ($2000).

Try to find a reliable second opinion. Maybe it does need a liner, maybe not, but 3500 quid is pretty excessive IMO. It should be half that much.
 
That is indeed a very high price, although as you are 3 storeys up and scaffold rarher than a scaffold tower may be required etc, it may just be a high price. Do get at least one other price to do it and understand what is required, as in, is it stainless steel,( it should be!), twin lined (it may not need to be), how are they fixing it at the top and what will the gather at the fireplace look like, etc.

It is true that if all you are getting is a sandy residue when sweeping the flue, rather than sand, then the morter in the flue may be breaking down and thereby the seal to adjacent rooms etc. This is not a good thing obviously. A liner may be the right thing to do now.
 
It was the bucket of clean sand that alerted me- there should have been 10 yrs of soot! I suppose he takes £50 for turning up with his bucket of sand trick then if he gets one idiot a week falling for his £3500 scam he's in the money. The last lot I 'caught in the act of doing nothing' I threw them out and told their boss he wasn't getting any money. We only light about six fires a year and I wanted it cleaned to prevent chimney fire, on the two occasions I've phoned a sweep now, I never got the chimney swept.
 
For such infrequent use I'd just put carbon monoxide sensors in any rooms the chimney passes through, light a fire and test if there is actually a problem first. You'd probably want the sensors anyway, they're cheap and effective.
 
If fires are infrequent then there may have been no soot. I'll second Martin's CO sensor recommendation: I'd get a combined CO and smoke detector in every room that the chimney passes through. For occasional use it's obviously not worth lining the chimney, even if you could do it for the $2000 we paid (ours is our only chimney and services the house boiler / water heater).
 
Out of curiosity, I brought in 15ft of flexible drain rod from the garage and put a 12" diameter sweep's brush on. After five minutes I got the same amount of material out as he did. Most of it was dark with the appearance of compost - not the black powdery soot I was expecting but equally not looking like his bucket which I suspect was mostly from the coal ash can under the fire. I'm tempted to do nothing to the chimney, it functions normally and I'm not inclined to take advice from a cowboy like the one who arrived today. Point taken about the CO detectors though, so thanks for that.
 
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