High Humidity - Problem?

[John Flynn]

I have a Mitsubishi MJ-E16PX Dehumidifier with which I am well pleased. I am using it in my bedroom at the moment and it seems to be extracting, what I think is, a lot of water. On average it is collecting 8 litres per 24 hours (the dehumidifier is on from 7am to

10pm). The humidity on the dehumidifier ranges from 60% -> 75%.

The room is pretty large 16 feet x 16 feet x 14 feet high. The building is an old victorian with stone walls. The bedroom has two addults and one baby sleeping in it overnight.

Is 8 litres per day to be expected ? Or do I have a problem - possible water ingres? If so how can go about finding the problem?

Thanks, J

[warwick]

I had this problem in my bedroom. It only started after I had new sash windows built so they sealed properly. I don't like dehumnidyfiers (too lazy to empty them). The other option is to get a fan installed to the outside. Baxi make a heat exchange fan specifically for this purpose (and the sound is barley noticeable in a bedroom) that is designed to be left on all day. As the hot air leaves the room, the heat is trapped in the exchanger, which in turn heats cold air as it is brought in from outside. The fan has changed my windows from dirpping with condensation every day, to dry .... the company which installed the fan for me was Protim Services.

[Andrew Gabriel]

Firstly, why do you think you have any problem with humidity? (What symptoms are you seeing?)

Secondly, drying out a room in a Victorian building (or even many modern buildings) in this way is going to damage the building. Timber (like floorboards) is going to curl up or warp, laths are going to shrink away from the plaster weakening ceilings, etc. I ran one for about 6 weeks, until I realised it was curling up the floor, which took over a year to recover.

Dehumidifiers (even small ones) need to be used with care, particulaly in old buildings. They are far too effective in the room they're in, and useless elsewhere. Opening windows and ventilating naturally is much better, and if you have a damp problem, fix that.

[Dave Plowman (News)]

I'm amazed you have a condensation problem at this time of the year - especially in an older property. If it has normal ventilation, I'd be rather worried.

[John Flynn]

The only reason that I think I have a problem is that the dehumidifier read 75% - which I think is quite high. I may be wrong in this assumption.

The fact that 8 litres of water is being extracted also leads me to think there is a problem. Should I expect this amount of water in a normal house?

The reason that I bought the dehumidifier was there is a general dampness problem in the house. So wanted to make sure that the humidity was lowered. I had tried opening windows to reduce the problem but this did not help.

Regards, J

[Dave Liquorice]

Two adults and a baby will produce an appreciable amount of water vapour purely from respiration (breathing), more if they are rather too warm and thus perspiring as well. I'm not sure of the exact figures but a pint/hr for an adult would not surprise me (google?). So to pull figures from nowhere inparticular half of that 8l could well from the occupants.

Where is the bathroom? Ours has no ventilation and condensation on the windows of the bedroom along a short corridor is a problem. Even at this time of year there will be signs on the windows after anyone has a bath, though not streaming like they do in the winter.

Real or percieved? Has the house central heating, ours does and sits at around 30% or lower in the winter but rises in the summer when the heating doesn't kick in, currently 60%. So 75% for an occupied house without CH is not out of order for this time of year.

A dehumidifier isn't really the answer, you need to cure the sources of moisture, ventilation in bathrooms and kitchens, pervention of penetrating or (rarely) rising damp.

[N. Thornton]

well all those indications point to something being wrong I guess. Just dont reduce the RH too much.

Regards, NT