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Posted to uk.d-i-y
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Trickle vents: fitting after-market ones
Kate wrote:
wrote:
There are no trickle vents in the uPVC window in my bedroom. 2.5m wide
x about 1.2m high.
Consequently, on winter mornings, there is a lot of condensation on the
windows. This is due to water vapour exhaled during sleeping. It's
amazing how much there is -- I have to sponge the windows down and then
leave the casement open during the day.
I am thinking of fitting one or two white plastic trickle vents. I
presume it is just a matter of drilling a few small holes through the
frame?
Any suppliers on line or in the high street? Wickes have some trickle
vents but they are for wooden windows, as far as I can see.
Anyone done this? Is it a DIY job or best left to someone who installs
uPVC windows?
Thanks,
Bruce
You don't have a ventilation problem; you have a reverse
chimney-effect problem.
I had the same thing with my patio door, a metal-framed one installed
circa 30 years ago. Moisture would condense on the frame, and on the
lower part of the glass, eventually leaving small patches of mould on
some of the hardwood frame. It took me a little while to work out what
was happening.
I traced the problem to a 'reverse chimney' effect due to the curtains
being closed. There was circa a 1" gap between the top of the curtains
and the ceiling, and similar one at the bottom.
As air trapped by the curtains cooled, it sank and emerged into the
dining area, to be replaced by warm moist air at the top. There comes
a point somewhere near but not at the bottom of the glass where the
temperature falls below the dew-point, and moisture condenses out.
This continues ad infinitum, drawing moisture from the room and
depositing it on the glass and frame. The colder the night, the
farther up the glass the condensation started.
Putting 'sammy snakes' (draught excluders) along the bottom of the
curtains stopped the problem completely. Although cutting off the flow
of air made the glass colder, the very limited airflow meant that
condensed vapour could not be replaced, and the problem has gone away.
The dining area is also a lot warmer!
I put a wireless thermometer between the curtains and the glass. With
no draught excluder in place, the temperature drop from ambient was
about 5 degC or so. With the sammy snakes in place, the thermometer
read just above the outside temperature, a drop on the night in
question of over 20 degC.
My suggestions: make sure that obvious sources of dampness are removed
from the rooms concerned and cut the air-flow off with
draught-excluders.
Great advice..I find similar problems in my single glazed house..the
consdensation is worse with curtains open than closed.
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