Help with ventilation/condensation!

[chris-s]

We are about to start re-decorating the downstairs but need some advice on how best to go about installing some extraction to overcome the excessive condensation we get during the winter months. In the winter the upstairs windows flood with condensation overnight. All windows are double glazed, but there are no trickle vents and even leaving them 'on the latch' doesn't really make much difference. Downstairs windows get a little but almost nothing in comparison. The only issue we get downstairs is the wallpaper under the window in the lounge and in the adjoining dining room going a little mouldy which is something we want to resolve as well, tho the dining window may be replaced with some patio doors.

Part of the cause is certainly the 150 gallon open-topped fish tank in the lounge lit by 1200 watts of metal halide lighting. Fortunately the filtration system is in the garage which must help to some extent (thats already vented so no condensation in there).

Bearing in mind that the condensation issue is upstairs, I'm not sure whether I should fit an extractor upstairs or in the lounge. If it was to go upstairs, I guess a ceiling vent into the loft piped thru to the outside wall would be the way to go? If it was to go in the lounge, then, as I see it, I have two options; a wall vent where the clock is in the photos below or a ceiling vent piped under the bedroom floor to the outside sofit. The latter sounds like a pita to install, I guess it wouldn't be so bad if the inside vent was just inside the room rather than over the fish tank, but I would be concerned about the fan noise since we sleep right above it. Visually, a wall fan isn't an issue.

So, any suggestions/kit recommendations on how best to go about quiet ventilation and prevention of mouldy wallpaper under the lounge window greatly appreciated!

Chris

 

[foxhole]

For a well ventilated house you need a vent in each bedroom [fan not needed] and a fan in both kitchen ans bathroom this should provide required ventilation, also check external vents to underfloor [if any] are clear of obstructions.You can retro fit trickle vents to some DG windows.
Also is the gas fire in use,? you have staining around it that might indicate a problem, gas fires also produce a lot of moisture.Also if that is a gas fire and you don't already have a vent in that room you has a serious health hazard.

 

[chris-s]

For a well ventilated house you need a vent in each bedroom [fan not needed] and a fan in both kitchen ans bathroom this should provide required ventilation, also check external vents to underfloor [if any] are clear of obstructions.You can retro fit trickle vents to some DG windows.

Thanks for the reply.

When you say "For a well ventilated house" do you mean "in order to acheive a well ventilated house" or "for a house that is otherwise well ventilated"? The best we've done is to leave windows on the latch even the bedrooms, but we still get loads of condensation which kind of suggests trickle vents alone wouldn't be enough.

The only vent bricks anywhere are in the kitchen wall, the upstairs is pretty much timber framed apart from the gable end.

Also is the gas fire in use,? you have staining around it that might indicate a problem, gas fires also produce a lot of moisture.Also if that is a gas fire and you don't already have a vent in that room you has a serious health hazard.

The gas fire is being removed, I don't know when it was last used and with 150 gallons of warm water and 1200 watts of halide lighting, we don't need much more heating downstairs


Chris

 

[STEVEROG]

I would look at removing the moisture the way you would in a bath / shower room. In simple terms you want to site an extraction vent as near to the source of moisture as possible. Ensure you get plenty of air extracted by fitting a quality in-line extraction fan in the pipe connected to the vent. Try to keep the pipe run from the vent to the outside as short as possible. You then need to make sure you have a sensible air inlet point such that the path of the air travels directly past the source of the moisture. A poor solution would be to site an extraction vent next to a window which would then mean that the vent would simply such air from the window (if it was open). I would try to get a ven down near ground level so that the air is sucked past the mosture source. In your case this is (you think) the fish tank. Don't forget to make sure the pipe from the vent to the outside has a slight slope towards the outside to allow any condensation to run off. You also want to lag the pipe so that ideally the moisture does not condense on the pipe walls at all ands exists as steam.

Remember that you can have all the windows you like wide open, if there is no air flow the 'steam' will simply rise and settle on the surfaces nearby, turn into water droplets and its soggy time!

Vent it!

 

[foxhole]

in order to acheive a well ventilated house
Leaving windows open gives very poor ventilation since vents need to be positioned at the top of walls to allow best circulation and unlike windows are open 24/7/365.
If you remove the fire then leaving it open will produce the best ventilation for that room.
Bathroom fan should run any time the bathroom is occupied regardless of use.
Kitchen should have a permanently open vent ideally opposite wall to cooker and extractor fan.[/b]

 

[chris-s]

Thanks for the replies.

One thing that you wouldn't see is some 120mm fans blowing across the top of the fish tank under the lights, these effectively blow the air towards the window, so an extraction point in that area would make sense. I don't know what height is available between the ceiling and bedroom floor to allow for a slope in the vent pipework tho.

Leaving the gas fire flue open is also quite do-able. I can easily make it presentable with a grill/screen of sorts.

Re kitchen, there is an airbrick diagonally opposite the cooker, so if we fit an extractor fan/hood above the cooker that sounds like it'll fit the bill.

Many thanks

Chris

 

[JohnD]

if you are losing water vapour from the tank, you should extract from above the tank with something like a cooker hood. Don't let the water escape into the rest of the house, trap it at source. The fan can be at the other end of the duct if you want, or somewhere along its length.

Hopefully yopu don't drape wet washing about the house, and you use the extractor fan during and after all showers, and, if you have a tumble drier, it is a vented type.

As for the condensation showing upstairs, water vapour is lighter than air so it rises up until something stops it.

see also //www.diynot.com/wiki/building:condensation_in_houses