Dehumidifier fills up VERY quickly... Causes?

James_Morgan_McGill

I recently bought a two-litre dehumidifier for my lower-ground bedroom in a Victorian flat conversion, because otherwise black mould grows on the outer wall. The room is a little below ground level. It looks out onto the path down the side of the house which is two foot higher.

The dehumidifier currently fills up about every two days. This happens even on very hot days, which I don't really understand because I thought it was something to do with rain, moisture in the air, etc. I'm sure if I didn't use it, the walls would grow mouldy again, and since I just repainted them I don't want this to happen. The mould however is just on the surface, it hasn't affected the plaster, and there is no rising damp.

Incidentally I am also unsure about whether having the window open helps, or causes, damp.

I don't dry any clothes in the room or put anything on the radiator, which anyway is off now it's spring. I don't have any furniture against the affected walls.

As I see it, there are quite a few possible causes of there being so much moisture in the air. Which of these do you think is the most important to address?:

* The bottom pane of the double-glazed window needs resealing. While there's no moisture on the outside of the panes, there's condensation inside.

*Directly above the outer wall that gets damp, there's a two-foot section of downpipe missing. This connects the gutter on this property with the slightly lower gutter of the property next door.

* There are several roof tiles missing directly above the missing downpipe.

* The gutters have not been cleaned in at least a decade.

(And yet it is not raining at present, but still the dehumidifier is filling up...)

* The bathroom (which goes onto the hall that connects with this bedroom) has a modern extractor fan, but no windows, so steam from showers is pushed pack into the flat. However the damp seems worse in the bedroom than in the hallway.

I had a quote of £300 to clean the gutters (3 floors up), replace the downpipe and the roof tiles, and I think it would be about £100 to get the window resealed, so it seems like it would be a good investment if it stops me having to spend so much time emptying the dehumidifier. But I feel I still don't really know what's causing it - and maybe it's just because the room is below ground level, it will always be a problem.

ariba10

It is just the dehumidifre doing it's job.

We have a larger one than that and it needs emptying a few times a week.

anotheruser

Yes - an efficient dehumidifier indeed!
You may see it claw out less and less water if you leave it on for a few days.

saveallmymoney

How much moisture does the average human give out whilst they are asleep? Assuming you are sleeping in this bedroom thats going to account for a lot of it.

Also over time it may decrease as the moisture comes out of everything in the room.

stator

Somewhere in your flat is producing damp, could be a leaking pipe or moisture coming in from outside. 1 litre per day is not a huge amount, in winter that would be normal. But when the humidity outside is very low like it is now, 1 litre per day is more than I would expect. I guess you have a leak somewhere

ripplyuk

The one I used needed emptying every couple of days.

I'm no expert but if this room is basically underground and the house is old, you might be fighting a losing battle unless there is serious money spent on it. My house is very old with solid walls and prone to damp. I either have the heat on or open the windows. Otherwise, I can smell damp building up.

I'd replace the tiles and the drainpipe and see if that helps. Maybe a damp specialist would be worthwhile? Also, watch out for your electricity bill with the dehumidifier. They cost quite a bit to run.

James_Morgan_McGill

Thanks, guys. I just had the carpet replaced, as well as scraping off all the old paint back to the plaster, and there aren't any damp patches on the floor or walls. I will guess it's a combination of the room being lower-ground, and the steam from the shower wafting in.

I've had the humidifier for a few months now, and the amount it's extracting is not reducing. But I'm glad that the walls at least are staying mould-free and pristine white.

The guy who was in this room before me had a bookshelf in the corner by the window. Now that REALLY made the damp worse - when he came to move out and removed all his books, the wall behind was covered in black. Now I know not to put anything in that corner.

Mojisola

James_Morgan_McGill wrote: »

* The bathroom (which goes onto the hall that connects with this bedroom) has a modern extractor fan, but no windows, so steam from showers is pushed pack into the flat.

Doesn't the extractor fan take the moist air outside? If not, what is the point of it?

lstar337

Mojisola wrote: »

Doesn't the extractor fan take the moist air outside? If not, what is the point of it?

It makes a pretty swirly pattern.

James_Morgan_McGill

Mojisola wrote: »

Doesn't the extractor fan take the moist air outside? If not, what is the point of it?

It's one of these:

http://www.amazon.co.uk/gp/product/B007XUCG8O?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00

I have it configured so it's always running at a low level, then extracts more when it detects the shower's on and the moisture is rising.

However I haven't yet had the area around it retiled, and since the old extractor was square and this one's round, it's not perfectly sealed. The electrician told me this means it won't be operating at its best - though I can still notice it's better than the old one.

System

James_Morgan_McGill wrote: »

Incidentally I am also unsure about whether having the window open helps, or causes, damp.

Are you running the dehumidifier with a window open?!