Manrose Remote Humidistat

[Paul Musgrave]

Hello,
I've recently moved into a house which has a wet room. There's a small window which can be opened quite wide and a small heated towel rail which doesn't get very hot.

After using the shower, I always leave the window open for about half and hour and leave the extractor fan running for as long as I can but the wet room has recently started to gain a slightly musky smell and black mould started forming in the corners of the ceiling.

Yesterday I had a larger towel rail installed which warms up the room better and had a Manrose remote humidistat installed but I cant work out the RH%. I had it set to 70% last night and the fan started working soon after the shower was turned on but it switched itself off about a minutes after I finished. Does the lower % mean the fan will run for longer? There is also a timer on the Manrose but as its on a pull cord, I believe its overwritten. Also, should I leave the window open or keep it closed?

 

[JohnD]

closed. and the door.

 

[Paul Musgrave]

And if I want to ensure that the extractor fan removes as much moisture as possible, should I set the humidistat at a high or low %?

 

[ericmark]

My house in winter around 45 to 50% so set at 45% it would never turn off, but at 55% it would, but summer that changes and this house may be at 60% humidity unless I use the air conditioning unit which removed moisture and puts it in a bottle for me to empty, last house was more like 65% in winter and 75% in summer, and father-in-laws house was 85% in winter 95% in summer he lived until 91 so can't be that bad.

But each house is different, that's why you can adjust it, I noted one house mould seemed to be a problem, but other two houses it was not, so sat back and tried to work out why. The wet room no problem the shower with good fitting door at bottom no problem house with shower over bath, problem.

Reason I think is with a shower in the bath there is a gap both below and above the shower, so damp air circulates, with both the wet room and shower cubical sealing at bottom the damp air does not circulate so the moisture drops out of the air and out of the drain.

Clearly a fan can help if it draws the moisture laden air and blows it outside, but if it draws the air into an otherwise dry air area then it will make it worse not better, so fully open wet room likely no problem, fit a curtain to limit where the shower sprays and then you start to circulate the damp air.

Also of course it must be able to draw in dry air, if the air it draws in is from a cold hall, then likely quite dry, but if the air your drawing in is already damp, then it can never work.

Relative humidity is dependent on temperature, so air at 10°C and 70% humidity has less moisture in the air to air at 20°C and 50% humidity. So where is the replacement air drawn from? In theory air at 0°C with have no moisture in the air, in practice not quite the case but at the moment this room a bedroom is 43% at 19.6°C and living room at 44% at 21.2°C. Likely living room in real terms is dryer.