green heating

[helprequired]

Hi, I have an attic conversion in my house with two large velux windows. The room gets really hot if there is any kind of sunlight outside. I want to be able to suck this hot air out of the room and blow it out downstairs. I basically need some kind of a pipe and fan system.

Any ideas would be really appreiciated.

Many thanks,

Neil

MOD

please see items 5 & 6a

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[felix]

Your fan and pipe idea sounds like as good a plan as any. The snag of course is that heat wants to go UP rather than DOWN. Instead of launching into this with a lot of trial and error I suggest you do a few calculations first. The important detail to work out is how much air you have to shift.

Start by checking just how hot it's getting up there. Suppose it's getting up to 25 deg C. You are going to shift this hot air and allow normal room temperature air at about 20 deg to come up the stairs and replace it. Now each cubic foot of air you move will carry about 11 milliwatt hours of heat per deg C. This means that for each cubic foot you shove down the pipe per hour you will put a grand total of 55 milliwatts into the rooms below!

Example: A fan moves 100 cu ft per minute which is 6000 per hour. This will move 330 watts of heat out of the attic and into your downstairs rooms. I suggest you will want a bigger fan - or multiple small ones - to make the whole project worth the effort.

As for the pipe run, I would be looking at running pipe(s) from high up in the attic - because that's where the hot air collects - down through the back(s) of fitted wardrobe(s) on the first floor and out through vent(s) in the ceiling below. It's a lot easier in a bungalow!