What are your opinions on fans in an observatory ??

Seanie- isn't the warmer air actually at ground level during the night? Might be an idea to have the intake fans at the top. Also, for those of you with metal roofs, you can significantly reduce the heat by painting the metal white- will reflect a lot of the light (heat). Difference of about 8C as far as I can remember.

dpower,

Having white painted metal on the outside for ROROs and domed buildings makes alot of sence, when you consider that most of the professional observatories are whitish looking on the outside.

I had built a 16 feet diameter steel dome many years ago. This was painted with aluminium paint on the outside which did help in reducing heat.

Eamonn A

Seanie- isn't the warmer air actually at ground level during the night?

But only for a short while - isn't this hence how we get fog at ground level?
The only concerm in my opinion is for the 5 or 6 months of spring/summer/autumn when we really have to deal with warm air. Otherwise, in winter, its cold during the day anyway, and the ground is not really going to hold in much heat at all from the daylight hours unlike in summer.
By the time it is dark enough to go observing in summer, the sun is already set by almost 3 hours anyway - the ground should be much more cooler by then (but in an observatory, the ground should be even more cooler again, as it didn't have any direct sunlight+heat shining on it).

So, you would still be sucking in cooler air from the bottom, and any heat within the observatory would then be sucked out at the top by natural convection.

I'm not saying I'm right either! Its just the way I perceive it. :idea:

Seanie.

This is why I've made up a set of switches where I can individually change the direction of any of the fans, and I can change to rpm speed fo any of them also..
I like to have control over the system, a total control freek. :lol:

ha, some much for control, I've just discovered that pc fans have a strict polarity, when wired correctly they work fine, but reversing polarity doesnt reverse the fan direction as presumed, it fries them. :shock:
Good thing I tried this on only one fan as a test, I'm off to maplin to get a replacement.