Air circulating fan- no energy cost Solved

[Chris43]

In some of the Gulf states, the houses are built with a central "chimney". The purpose is that the air passing over the top, draws air in the bottom and up and out, thereby cooling the rest of the house. I guess its the same principle as the Fume cupboard.

I wonder if when I open my bottom vents and top vents in the greenhouse it works the same way - hopefully!

[Julie]

Hahah, Tony! They did that at my Dad's old workplace with the loo fan. It was his first day, and he was asked to find out why the thing worked OK but the loo was still not smelling of roses. Oh great, he thought... just started here and I'm working in the flipping loo!

Fumes in the lab... our fume hood fan worked fine until my lab pal, a ceramics chemist, cleaned some things with aqua regia and thought, well it's organic isn't it? I'll add the leftover aqua regia to the organic waste bottle.

I wish I'd been there to see/hear the bang, it must have surpassed my "error of judgement" with lithium aluminium hydride.

[Derek]

iann Wrote:
-------------------------------------------------------
> You can buy solar powered fans, which would be the
> best solution for obvious reasons, but they aren't
> cheap (at the power levels you need) and they
> aren't the sort of thing that's easy to cobble
> together from stuff you find in the attic

Hi Iann
I have a small (6inch) solar powered fan which moves the air around in my 'hotbox' and helps keep the temperature down on hot sunny days. I've no idea where I bought it due to old age rapidly setting in (!) and I am seeking a more powerful version to substitute for the mains powered fans I use at the moment. Any ideas on a good source?
I abandoned the wind powered idea some years ago because invariably there will be hardly any wind on a hot summer's day, especially in a sheltered back garden.
Regards Derek Milton Keynes UK

[iann]

Derek, check out boating shops.

[Agavegeoff]

Hi, All.

Or Caravan and camping shops for solar panels

[Bill]

Plenty of links here Derek

Solar Fans

[iann]

Chris, the theory is certainly to create a vertical air flow driven by convection from low level vents to high level vents. And it does move quite a bit of air through when the sun is out, but most greenhouses don't have enough roof vents or low levels vents to make it work fully, plus staging crammed with pots doesn't always let air flow where it is needed. And of course you get no air movement at all on a foggy winter day.

[Derek]

Thanks all for the information. I see that Maplins have all the bits and pieces to construct your own solar fans at a very reasonable cost, and as an inveterate diy-er I will probably try this. Other links take me to interesting solar panels 12V 6W at only ?17 which should be enough power to shift some air, so now looking for a suitable fan.
Regards Derek Milton Keynes UK