Condensation?? (merged threads)

fat-tony_4

Basically it's water vapour hitting a cold surface, condensing and becoming liquid. The casues of the water vapour are many.
1)Us, we produce through sweat and breathing. In a bedroom this is an issue..I used to notice more if I'd been particularly sweaty as a result of drinking too much.
2)Cooking and Washing, need good ventilation for both, and even then you'd have some vapour in the rest of the house.
3)Penetrating damp... look for the causes, dodgy guttering, rendering, roof
4) House too cold, is loft insulated, is heating working ok. Warm air less condensation as the water finds it harder to escape.

There are a few. However if you are running a dehumidifier and have your bedroom reasonably ventillated and house warm I'm at a bit of a loss...

fat-tony

WestonDave

Condensation will happen when warm air hits a cold surface - basically warm air can hold more moisture than cold air, so when it cools rapidly because it hits a window it drops the excess moisture as condensation.

I'm guessing here, but I suspect what you are doing is heading off to bed in a nice warm room, with all the windows tightly shut to keep the heat in. However whilst that is very heat efficient, it also means that as you (and your partner if you have one!) breathe out moist air, it stays trapped in the room getting wetter and wetter. My guess is that your walls are probably cavity insulated (either retrospectively or done on construction if the house is relatively new) but you have a solid lintel above the window which is transmitting cold from outside. The coldest points in the room are therefore the window panes and the lintel so that is where the water is being "dropped" out of the room. In short your last cup of tea before bed is ending up on your windowsill!

This will also be made worse if you are drying washing on the radiators or leaving wet towels/robes around the room after showering, or if you have an ensuite that doesn't vent outside and the steam is being allowed into the main bedroom.

Simplest solution is to open the window a bit at night, and in the morning dry the water up with some v cheap kitchen towel/toilet roll and dispose of it around the room. The dehumidifier is just an expensive way of doing the same job - i.e. getting the water out of the room and down the toilet! If you just leave the water to dry during the day all its doing is evaporating into the air, ready to drop again when the window cools at night.

fluffymuffy

WestonDave wrote: »

Simplest solution is to open the window a bit at night

I always assume everyone does this anyway . But I guess you might be right there. Perhaps they don't?

We still need our dehumidifyer as it lives downstairs and collects a lot of water in the conservatory overnight. But I certainly wouldn't sleep in a bedroom with the window closed - whatever the weather - I'd be breathing in the air that OH had just breathed out !.

rachbro

:T All your replies are much appreciated

27col

I am at a loss to figure out why people need to buy dehumidifiers. I have had 3 houses, two of which I built myself. There was condensation in the first one, which had virtually no insulation and no heating except for an electric fire in the lounge.
The other two had double glazing, cavity wall insulation and roof insulation, although not as much as would be required now. I can honestly say that I have never had any problems with condensation. Indeed I was not really aware of the existence of dehumidifiers until I joined MSE.
Water vapour condenses onto cold surfaces. If the surface is warm, then moisture is less likely to condense onto it. By the same token, if the air is warm then it will hold much more water than will cool air.
While I am prepared to accept that some peoples life style will generate much more water than mine does. It does seem to me, that the amount of water vapour being generated, could be reduced by modification of life style in some way.
As latecomer and richardw say, people need to check out what is causing their condensation. Just buying a dehumidifier is just masking the problem. Maybe they should talk to friends and neighbours and compare life styles to see what the ones who are not getting condensation problems, are doing, that is different from what they are doing.
Obviously, every one's arrangements and housing is different, but I bet there would be something to be learned.
I might add that we never open the windows in winter, the only ventilation being provided by the small vents in the DG. Normally, any changes of air required are provided by the passage of ourselves through the front and back doors.
I am not going to pay good money for heat that I then let out of the window.
Please excuse me for sounding off, but I do feel strongly about insulation and keeping my house comfortable.

KE7285

Hey all. Ive just been looking into this myself. In my case, our ceilings have light mould growing on them and we ALWAYS have condensation on our windows in the morning. Ive been researching all day and from what i can make out, the best thing in most cases is ventilation. In our case, we are going to need to look into new loft insulation. I suppose it makes sense - warm air hitting a cold ceiling will inevitably cause damp.

Does anyone have any advice on what to do to remove the mould once the cause has been fixed? Really dont want to have to re-paper the ceiling if i can get away with it! :-)

latecomer

you can get a mould killer spray but its nasty stuff so I've no idea what it would do to your wall paper though.

legless

sweetnskint wrote: »

i got some crystals that absorb moisture and collect water in a container-not big at all then you just throw water away and add new crystals about 6pound at woolworths also can buy refils quite cheaply.worth a try- hope this helps!

Hi What do they call the crystals?

markelock

show me a victorian house with single glazed wood sashes, single brick walls, with only loft insulation that won't get condensation?

one good reason for de-humidifiers.

TimBuckTeeth

legless wrote: »

Hi What do they call the crystals?

They are sold in bags in places like Wilkinsons, Woolworths, B&Q etc. They are best used in a box designed for them which has a plastic grille to allow the liquid to drain into the lower half . Usually just called something like "dehumidifier refill". They contain flakes of calcium carbonate.
They are OK for fitted cupboards and other small enclosed spaces, but would not be that effective for a whole room.