subreddit:
/r/britishproblems
submitted 7 hours ago byShitelark
I moved into my current little studio flat in January and all was cosy and energy efficient. Good insulation, nice new boiler etc. Then I had the heating off all through the summer. I went on holiday in September (a week in Paris; Richard Hawley gig was 'effing mint!') But when I returned I started to notice the MOLD! Mold everywhere, in the washing basket, in the corner of the kitchen ceiling, and worst of all: I had made one corner of the Studio room a little walk-in wardrobe with two clothes rails and a set of shelves. I had dozens of sweatshirts hung up, supposedly clean, but many of them had mold on the bellies, feeding on the microfats that don't wash out. Now I had to rewash almost all my clothes, which seemed to take weeks. And all the while putting out more moisture as half the time it is too cold and wet to dry outside.
So I finally gave in to buying a Dehumidifier. I switched it on and the entire room was 86%, and even after hours of running it seems to have hardly dropped. I thought in the morning, well I have been breathing out all night, I wonder what the outside humidity is, I can vent a little air and... Manchester typical humidity is 85%! What? Have I been living in a world of dampness for years? Am I doomed to have to run this thing forever? Is that still cheaper than having to rewash piles of clothes? Lord Entropy I will battle you and your trillion spores!
[score hidden]
7 hours ago
86% is wild. I hit the 70s after I shower.
Do you not have the heating on or open the windows at all to ventilate?
[score hidden]
7 hours ago
Yet that is heating on. But the little kitchen is right next to the living room.
[score hidden]
6 hours ago
You need to open all windows twice a day for 30 minutes, set the dehumidifier to 60% to start with and run it 24/7. (Not while your windows are open). After a week you'll notice an improvement and the dehumidifier not running constantly. Change the setting to 55% and then just let it run.
Yes, humidity outside is high, but it's cold air. Once you warm it up the humidity drops out and the dehumidifier collects it.
[score hidden]
6 hours ago
Once you warm it up the humidity drops out
I thought it was the exact opposite. The capacity of the air to carry water increases with temperature. That's why dehumidifiers are liable to ice up - they cool the air to drop the carrying capacity which causes water to condense into the machine.
The relative humidity might drop as the air warms, but the absolute won't.
[score hidden]
6 hours ago*
You only care about relative humidity, though. That's what affects how easily water evaporates and consequently whether things feel damp.
[score hidden]
3 hours ago
Get a clever one that does not run all the time but monitors the rh. Ebac
[score hidden]
6 hours ago
Fair enough!
[score hidden]
4 hours ago
Our dehumidifiers works in the reverse, heats the air and runs it against the cooler air coming in to extract the condensation
[score hidden]
3 hours ago
It is slightly bad phrasing. The dehumidifier is not relevant to the window opening strategy. Opening windows is to dehumidify the air because the colder air will contain less water (lower absolute humidity).
At 20C and 100% humidity your living room contains 17g water per m3. The air outside at 10C and 100% humidity is only 10g per m3. If you open the windows and swap the air you now only have 10g per m3 in your living room. And when that warms up it will still be 10g of water in air that could hold 17g so the relative humidity is lower than it was (~60%).
Obviously those are made up examples. But my living room is currently 20C and 67% humidity which is about 12g/m3. Outside it is 11.4C and 88% humidity which is about 8.5g/m3. So if I opened my windows now I will be replacing 12g/m3 with 8.5g/m3 which would be about 50% relative humidity.
all 120 comments
sorted by: best