Keep it cool

[KenGee (Kenith Gee)]

Hi all help
How do you keep your observatory cool? I've got a sirius observatory with a solar vent. But It get's very hot during summer where I live. I'm thinking of putting a small airconditioner in it, but I don't want to cut any big holes. Any ideas or help would be great.

[Phil]

I live in Rockhampton and it get very hot up hear. In my dome i have the solar vent plus i run a small fan inside 24/7 it keeps the temp down a bit.
Phil

[rogerg (Roger)]

When I first built my observatory it was a "wheat" colour. The inside would regularly be about 15 degrees hotter than the outside - meaning it often reached 50+ degrees.

I then painted the roof white and put white shadecloth double thickness on the north wall. Since then, the temperature gets up to about 5 degrees above outside.

I've also insulated it now so the "temperature curve" is slower - takes most of the day to get up to 5 degrees above outside.

I have an exhaust fan that I have used now and then, but to be honest it hasn't made a big difference. In fact, I've never found there has been a noticable difference of more than 1 degree with it on vs off. So I don't bother with it most of the time that I'm not in there.

So from my experience, fans don't do much, colour does.

I am about to put a portable aircon in there, but only for when I'm in there. I don't have any problem with it getting up to 40 or 45 when I'm not in there - sure it would be nice if it didn't, but I haven't found any problems with that.

Being tin mine cools down extremely quickly once the sun leaves it, which is about 2 hours before dark for me. A little less quick now that I have insulation, but still very quick.

I have sometimes thought that if I were worried, I'd put a shadecloth structure over it, which moved with the roof, and separated from the roof to allow an air gap. I think stopping the heat hitting it/being absorbed in the first place would be much more effective (not to mention cheaper and environmentally friendly) than trying to counter-act the heat with cooling.

[rumples riot]

Maybe the whirly gig, perhaps two of them. They are very efficient at removing heat and cost nothing. Heat moving out of a roof forces them to turn even on windless days.

[jjjnettie (Jeanette)]

The dome of my observatory will be painted with Insulpaint. http://www.insulpaint.com.au/
We used it with great success on the exterior roof of our Coffee Cart.
The roof of the cart is steel, with this paint on we can be out in full sun, 43 degrees and the roof will only be warm to the touch.
I can't recommend it highly enough.:thumbsu p:

[leon]

Yep JJ, I know what you mean, I like some others run a 100mm exhust fan, plus a 200mm ordinary fan 24 hours a day, seven days a week, also my observatory is full insulated in the walls, roof and doors.

On the hottest of days the temp is reduced by 6-8 degrees, i feel it is worth the extra in power cost to protect a substantial investment.

Leon

[Aster]

Read some american website a couple of weeks ago, don't ask where, were they did some tests on them portable observatories with dome.

Wife wanted to have the outside colour matching the surrounding garden, Green. Bloke installed fans, vents etc. without much success. It was still very hot inside. Some paint tech bloke told him to paint the inside black-black and it worked, much cooler inside now. Has something to do with solar rays not penetrating the INTERIOR black paint, whereas when it is used on the OUTSIDE the interior becomes an oven.

Can't think of the website, something Dome, follow the links to the tests.

[rogerg (Roger)]

Originally Posted by Aster

...Some paint tech bloke told him to paint the inside black-black and it worked, much cooler inside now....

It'd think it'd be because black aborbs heat where as white does not. Hence if the inside is darker than the houseide, heat would be being absorbed by the black inside and perhaps radiated by the lighter colour outside. I've often wondered if it would work in practice, but haven't tried. Interesting to hear it does!

[xelasnave]

I have two computer fans in the wall near the ceiling run by a solar panel.
No battery so if the Sun shines the fans work.

So far it seems to do a good job... it is a unpainted garden shed lined with pine.. there is a hole in the floor (around the pier) and the lot stands on cement which seems to retain coolness because its under the shed..I think so far it is working well but have not taken temp readings..but it seems cooler when I first open it than after standing in there with the door open..
alex

[g__day (Matthew)]

Stop heat before it enters (shade cloth), next paint the outside white (a shade not a colour by the way) - these are the two best things you can do - far better than insultation (which is still useful). Have a vent to exhaust hot air if needed.


The inside colour (or shade - say black) helps your eyes to night adjust in low light - by minimising reflections.

[coldspace]

You can buy from most major retailers a small compressor powered refrigerated portable air-conditioner that is one complete unit around the size of a esky tilted on its side. They come with a 150mm flexible duct that you stick out of a door or just cut a small 150mm opening down low and stick it outside ,this duct transfers the heat from the condenser coil to the outside air. They have a water container in the bottom that you need to empty every so often. Get at least one that has a capacity of 3 to 4 kilowatts. The TCL brand sold by Retravision has the largest capacity of 4 kilowatts and this unit still runs of a 10 amp plug. All of the other heat improvement methods mentioned before will work but if you are going to use you dome during the day for processing work ect, you will need to put in an A/C to get rid of the humidity.

Regards Matt.

[timelord (Al)]

I use a 6" 12v dc fan with a thermostat control powered by 10 watt solar panel drawing cool air from under my house via 6" pvc stormwater pipe. thermostat set to 30 degrees so only runs above that temp.
Total cost for the 3 items $180 plus pvc pipe--works great.

[KenGee (Kenith Gee)]

Thanks for the suggestion everyone, I decided that a fan just wouldn’t cut it were I live. So I found a 2nd hand portable air conditioner. It takes up a fair bit of room but I think it’s worth it, it should help with cool down times as well. It took me a while to physic myself up to cut into my Sirius Observatory and I think I need to put a fly screen over the vent. As you can see by the pics I’m still waiting on the pier, Which I’ve been told today is in the mail. So once that is setup I can go hell bent for leather. Imaging and telling Alexander Gravity does indeed Suck!

[xelasnave]

So good to see it all there for you Kenny gravity is only for cloudy times by the way get some images happening
alex