I am thinking about constructing a tube to suck hot air from near the ceiling of a high-ceiling room and reintroduce it and mix it with the colder air at floor level. I have seen these things at work in other buildings but I do not know what they are called.
I would like to read a bit more about them and find out if any improvements from mixing hot air into the cold are worth the effort but I am stuck by not knowing a suitable search term.
Any suggestions. please?
Nick
Air recirculation. It tends to arise in domestic air heating systems.
Ceiling fan?
That would do the same job but more conspicuously. The tube I have described in my reply to Harry just sits quetly in the corner of the room and the airflow is no more than from a quiet desktop computer.
Nick
Thanks but that is a more sophisticated system than I have in mind.
The thing I am thinking of is nothing more than an open-ended vertical tube mounted against a wall - one in a school where I used to work was rectangular section and simply looked like a covering for pipes or cables.
At one end of the tube is a fan - like a desktop computer fan - and it sucks the hot air in at the top and blows it out at the bottom to even out the temperature through the room.
Nick
use a fan blowing down instead ?...seen it done in a church used as offices....
That is the thing! Thanks for that! And the link takes me somewhere I can do some calculations to see if it will be worthwhile.
Thanks again,
Nick
That is exactly the sort of thing I had in mind. Probably done before redecorating the room so I can paper/paint/blend it in some way so that it does not look like PVC guttering on the inside wall :-)
Nick
Covid 19 distribution system?
Dust recirculation system
Easy enough to put some UV C lights in the tube. The airflow will cool the lights and the lights will disinfect the air.
Owain
Unlikely. Most dust sinks to the floor; it will be picking up cleaner air from near the ceiling.
Andy
Disinfection requires dangerous amounts of UVC not compatible with human occupation.
NT
It is not supposed to be like a Henry vacuum cleaner on blow: it is a very gentle displacement of the air with the volume of the room being turned over roughly 2-4 times an hour.
Nick
The UVC would be contained in the air duct.
My point is not that this would be a practical application for the OP; merely refuting the comment that air duct is necessarily a Covid "distribution system".
Owain
Necessarily no. Practically yes.
Energy prices went up a lot today which was exactly the round tuit that I needed for this project.
Just a couple of questions:
Any thoughts about whether the system would work better by blowing the hot upper air down the tube or the cold lower air up?
I wondered about making a controller to switch it on when there was too much hot air on the ceiling - would a pair of thermocouples, a differential amp like an op-amp and a switching circuit do? Or is it just not worth the extra faff?
Thanks,
Nick
Ah, the joys of those characterful 'high ceilings' :-)
hmmmh or two NTCs in a bridge, buffer and a comparator? more sensitive, cheaper, less to amplify...
Though: probably not worth it. I have a shed with a gas heater, and use a fan to mix the heat around in winter when its freezing.
As there's gas but no mains, I use a cheap USB-powered fan and a worn-out power bank that's too weak to do a phone any good. The fan draws about 28 mA at 5 Volts. It is maybe 5" in diameter, so: not a large fan. It does make a noticeable difference, enough for me to miss it when its off.
(Industrial ceiling fans google up at up to 24 ft / 7 meters diameter.You could run one of those very slowly and mix *all* the air silently...)
Thomas Prufer
Adriano? Wot? The football player? I suppose he's tall enough to just stand there and wave the air around a bit but I don't suppose I could afford his fees.
The trouble with the Arduino and Raspberry Pi is that I already have a drawer full of op-amps and switching transistors. "If all you have is a hammer, everything looks like a nail"
Nick
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