Fan venting into loft - ok?

[John Fryatt]

Hi,

I work from home and my office, in a bedroom upstairs, seems to be full of computers and other such bits. All this stuff generates heat, plus the room faces south, so it can get quite warm in there.

I am considering ways of getting some forced ventilation going and was wondering about a fan (Xpelair, Vent-axia) fitted into the ceiling blowing into the loft. I'm considering this because it appears easier to do than knocking a hole in the wall (and more easily reversible).

Do you think this is a reasonable approach? Any problems to look out for?

The Vent-axia site shows such an arrangement for a bathroom, but with a flexi-pipe taking the exhaust out through the eaves. I'm assuming that this is because you don't particularly want to blow damp air/steam into the loft, but I'm talking about a dry room so perhaps the duct isn't necessary in this case?

I suppose full air-con might be best, but it's a) expensive, b) bulky, and c) we don't get that much hot weather so I'm not sure it's necessary. Hopefully the fan would be enough to deal with just the computer heat, except for the few scorching days we get. On those days I'll go somewhere else with a cold beer! ;-)

All advice gratefully received.

Thanks.

[BigWallop]

It's not a good idea to have holes through in to your loft space, especially from a space that could be at higher fire risk than other areas of the house. The last thing you want in that situation is for the fire to easily jump through in to the roof space of the property.

A good solution is make a screen in the top section of the window, so that you can open the window a little and have the screen in place to stop debris and insects getting passed it. An open door and a window at the other side of the house can then be opened to give a controlled air flow throughout the whole house. You may even install a fan in one of the screens, which would give some forced air intake or output venting if really needed.

If you do want to go for the ceiling vent option, then make sure you have proper fire / heat resistant ducting above it, which will take the air away to the outside world at the eaves or to a vent slate on the roof itself. And that the fan or the ducting has some sort of safety damper that closes automatically in the event of a fire condition to stop air being drawn in and feeding the fire again. Don't give fire a chance, even in the slightest. And please, don't be the type of person to say "It can't / won't happen to me". It's just not worth it.

[John Fryatt]

Good point. I hadn't considerd that, I must admit.

Re. windows, opening them is ok, I do that now. The resulting ventilation isn't really enough though, hence the fan.

One option I have considered is to make a little frame to mount a fan on the window frame, to actively push air out of the window. It's a bit cumbersome and untidy though, inc. the wiring.

I will bear in mind the fire issues. Thanks.

John

[Ian_m]

A mate did this in his office in a bedroom a 4 (or 6) inch fan to vent hot air into loft, not very successful (it was a large room in Victorian house).

- Makes a "bloomin" racket, more than PC,'s.

- When fan was off on some hot days, hot air from loft space "poured"/was blown into the room making it even hotter.

- All types of crap and dust fell from the loft through the fan when off.

- Signs of condensation in the loft in the winter, when warm air from the room entered the loft and condensed on the timbers and roof.

Ended up filling hole, buying a portable air conditioner the type you add water to to increase cooling and put a vent pipe out the window. Changed that, as always running out of water and the warm vented air blew back into room, to a two part dangle fan air conditioner, where you hang a bit out of window. Much better but still need pipes hanging out of open window letting air in. Eventually got the two part unit professionally fitted via holes and connectors in wall meaning you can close the windows, and guess what it worked......room was cold/cool.

But cost best part of £1000 and it worked..

[bigcat]

4 or 6" is hopelessly inadequate for this.

Fanning outdoor air on on a hot day wont really help in most cases, since its just as hot outside. A ceiling fans just as good for that. It does help a lot in evenings and at night, when outside is cooler.

Shading the house is a good start, eg with climbers that lose their leaves in winter.

Just venting the loft helps too, they get very hot up there, and the heat gets through. Insulating the loft floor is another way to solve it.

If the house is brick or crete, best thing is ventilate heavily in evening and at night, this stores lots of coolth in the structure, then close it up in day time.

NT