ChatterBank1 min ago
Dehumidifier + Condensation
18 Answers
I have a problem with condensation in one bedroom to the point that mould has started to develop. I'm dealing with the mould but obviously need to sort the condensation out.
I am looking at dehumidifiers and am somewhat confused. Many claim to handle 20 litres of water in a 24 hour period but the water tanks are only 2.5 litres, a few with 4 litre tanks. Continuous drainage is not possible so I would have to empty the water tank many times a day. It is very likely the tank would be full and stop working just when it is needed most - during the night.
I dry the windows every morning and open them to let fresh air in, any other ideas? Is there a dehumidifier out there that is more suited to my needs?
I am looking at dehumidifiers and am somewhat confused. Many claim to handle 20 litres of water in a 24 hour period but the water tanks are only 2.5 litres, a few with 4 litre tanks. Continuous drainage is not possible so I would have to empty the water tank many times a day. It is very likely the tank would be full and stop working just when it is needed most - during the night.
I dry the windows every morning and open them to let fresh air in, any other ideas? Is there a dehumidifier out there that is more suited to my needs?
Answers
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The fact that a dehumidifier can handle up to 20 litres of water per day doesn't mean that it will actually produce anything like that amount. It can't remove water from the air if that water isn't there in the first place and you'd probably need to be living on a Louisiana swamp for that amount of water to be present! (The 'volume per day' figure is really an indication of a dehumidifier's efficiency, not of how much water will actually be drawn from the air).
About a quarter of a century ago, I had an overflowing cistern that resulted in my living room carpet getting completely soaked, with a small amount of standing water on top of it. I hired an 'industrial' dehumidifier to help dry the room out. It did a very good job but I still didn't need to empty the tank more than once per day and you won't either with any decent humidifier.
About a quarter of a century ago, I had an overflowing cistern that resulted in my living room carpet getting completely soaked, with a small amount of standing water on top of it. I hired an 'industrial' dehumidifier to help dry the room out. It did a very good job but I still didn't need to empty the tank more than once per day and you won't either with any decent humidifier.
We have 2 dehumidifiers constantly on. On average, we probably empty them once every 2 or 3 days.
If I remember correctly, ours have a 10 litre per day capacity and a 2 litre tank (ish?).
Condensation is caused by damp air coming into contact with a cold surface. To rectify the problem, you need to either increase the temperature of the surface, or remove the moisture from the air.
Increasing the surface temperature can be achieved by simply turning the heating up, or by improving the insulation. For instance if you have walls that are not adequately insulated, these will be more prone to condensation. Similarly, single glazed windows, or substandard double glazed windows will also be more prone to condensation.
Removing moisture from the air can be achieved by improving ventilation or by using a dehumidifier.
I wouldn't part with mine now :)
If I remember correctly, ours have a 10 litre per day capacity and a 2 litre tank (ish?).
Condensation is caused by damp air coming into contact with a cold surface. To rectify the problem, you need to either increase the temperature of the surface, or remove the moisture from the air.
Increasing the surface temperature can be achieved by simply turning the heating up, or by improving the insulation. For instance if you have walls that are not adequately insulated, these will be more prone to condensation. Similarly, single glazed windows, or substandard double glazed windows will also be more prone to condensation.
Removing moisture from the air can be achieved by improving ventilation or by using a dehumidifier.
I wouldn't part with mine now :)
If you own the property Barry, have a look into DCV - IO had terrible trouble with mould in a new build, got the house insulated - didn't help and it turned out it needed ventilation so a trip to my local credit union, i got the work done, it's all in the attic and have not had a mould issue since( Demand control ventilation (DCV) is an intelligent ventilation method that ensures good indoor air quality and saves energy) It was worth it in the long term
We use a dehumidifier and run it for a couple of hours when its cold and there's steam from shower/cooking/kettle/tumble drier etc it's amazing how much water can be collected in them. We empty the container after each session rather than wait for it to be full. We also use a Karcher window vac to clear moisture from all windows, shower door and shower tiles and it comes well recommended by us.
This comes up a lot Barry. Especially in this country, at this time of year.
I've said it before. De-humidifiers only address the symptoms: not the causes.
237sj's surveyor is right. Heating and ventilation.
I imagine the mould is developing at the top of the wall, in the angle between the wall and the ceiling.
It's rather a shame that most people set their heating to go off at night, at precisely the time that it's needed most. The only way to avoid having the heating on is to apply extra insulation to the wall surface and/or increase ventilation.
At the very least... add ventilation. Trickle vents in the windows are effective to combat condensation on glass, and do help with the walls.
Start with a simple method. Add a vent /grill fitted into the ceiling at any point where the mould is developing. You may only need a couple of them. A 9"x6" grill will do.
The pukka way is to duct from the vent, through the roofspace, to the outside. For starters, just let it vent into the roofspace without ducting. The space should be well ventilated anyway in a well-designed roof. It's a start.
I've sorted this before many times. If mould is all over an external wall, then I've just added modern foam insulation board (finished with plasterboard etc.) That, with ceiling ventilation does the job, even without added heating. It's not guaranteed. It really does need the air temperature in the room to be raised above the dew-point.
So easy in a new-build. Much more difficult in any property built in the last 100 years.
Houses older than that are often so leaky, they ventilate themselves.
I do wish I could offer a magic solution Barry, but it really is a matter of trial and error.
Either heat, or "real" ventilation. Preferably both.
I've said it before. De-humidifiers only address the symptoms: not the causes.
237sj's surveyor is right. Heating and ventilation.
I imagine the mould is developing at the top of the wall, in the angle between the wall and the ceiling.
It's rather a shame that most people set their heating to go off at night, at precisely the time that it's needed most. The only way to avoid having the heating on is to apply extra insulation to the wall surface and/or increase ventilation.
At the very least... add ventilation. Trickle vents in the windows are effective to combat condensation on glass, and do help with the walls.
Start with a simple method. Add a vent /grill fitted into the ceiling at any point where the mould is developing. You may only need a couple of them. A 9"x6" grill will do.
The pukka way is to duct from the vent, through the roofspace, to the outside. For starters, just let it vent into the roofspace without ducting. The space should be well ventilated anyway in a well-designed roof. It's a start.
I've sorted this before many times. If mould is all over an external wall, then I've just added modern foam insulation board (finished with plasterboard etc.) That, with ceiling ventilation does the job, even without added heating. It's not guaranteed. It really does need the air temperature in the room to be raised above the dew-point.
So easy in a new-build. Much more difficult in any property built in the last 100 years.
Houses older than that are often so leaky, they ventilate themselves.
I do wish I could offer a magic solution Barry, but it really is a matter of trial and error.
Either heat, or "real" ventilation. Preferably both.
Sounds as if trickle vents could help here Barry.
Quite easy to fit if you still have your original timber windows.
https:/
A little more involved with uPVC windows, but the same principal.
Quite easy to fit if you still have your original timber windows.
https:/
A little more involved with uPVC windows, but the same principal.
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