Thinking about ways to reduce the massive syphon effect up the chimbley when there's a howling gale outside, I thought of one of those stack pipes that bends over to vent horizontally, but can rotate and has a vane so it always points downwind.
After some googling it appears these are called "lobster back cowls".
Anyone ever used one of these and are they effective? I can use a balloon in the unused chimney but would like to reduce the gale effect for the one that's in frequent use.
the problem with these are that if the wind direction is changing and its only a light breeze it can blow into the opening without turning the cowl result is you get the room filled with the smell of soot.
I thought their purpose was to eliminate downdraughts when the chimney is not in use, rather than to reduce updraughts when it is.
Wouldn't you get a syphon effect in high winds, when the exit of the cowl points downwind?
If you have an enclosed stove, have you considered an adjustable baffle on the stovepipe?
In message , " snipped-for-privacy@gglz.com" writes
I made a damper for our open fire.
Bit of a struggle securing the frame inside the chimney. Hinged flap, raised by a bit of picture chain fed through a tube in the chimney breast.
Soot has not been a problem, so far.
regards
If your local winds are changeable, you're probably better off with an omnidirectional H cowl instead.
Really though, if I wanted to block draught through a chimney, I'd look at a removable block below.
You mean, as in a damper or chimney balloon? The folks who put the fireplace in (before we owned the house) seemed to think a damper was not possible (it's a open fire).
The winds are variable and can be quite strong - from N, E, and W so far this winter. We're getting double-glazing next week and cavity wall insulation in a few weeks, I was hoping to avoid having all the good from that negated by the heat being syphoned up the chimney.
I'll take a look at the H cowl - thanks.
Those things are designed to improve the flow of air. So putting one up will increase the gale to a hurricane.
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