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Old 24-01-2019, 12:25 PM
Jasp05 (Aaron)
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Insulation of Observatory

Hi guys,

I picked up a garden shed (3mtrs long x 1.2mtrs wide x 1.8mtrs high) to use as an observatory in my backyard.

It's just a lift off roof currently but I am looking to insulate the walls and roof to try and minimize the heat coming through during the day.

Budget is tight, but looking for some ideas. Thinking Polystyrene foam sheets at this stage, say 15-25mm thick. Just use silicon or some other adhesive to glue to the walls.

Given its a small shed I don't want to use anything too thick, but also want to get some protection from radiant heat.

Anyone else got some ideas or advice? Or do I not need to be concerned about insulation?? (my telescope sits on a pretty high pier so I can see over the side walls without obstruction and therfore is in close proximity with the roof).
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Old 24-01-2019, 01:56 PM
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Tinderboxsky (Steve)
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Do you have any way of stopping the direct sunlight from hitting the shed in the first place?
Is it possible to suspend, say, 90% shade cloth with an air gap between the two. I have found this quite effective in another situation where I needed to cut down heating from direct Sun light.
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Old 24-01-2019, 02:08 PM
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Aaron, probably a couple of things to think about.

Sure you can spend a lot and line the walls and ceiling with proper insulation, or you can go with what you are thinking.

It will help but it wont get rid of all the heat.

As you know heat rises and needs an outlet so an exhaust fan or some other device to let the heat out would do a good job.

When I built my Observatory some time ago It was insulated to within a inch of its life however it still got hot.

I had a fan inside the Observatory that ran 24/7 to circulate the air and exhaust fan to suck it out.

With a tin shed as you have it heats up very quick however i cools just as quick when the Sun goes down.

Installing a fly like one dose over a tent is also a good idea as it lets the air flow in between the roof and the fly, but of course you need a decent gap between the roof and the fly

Leon
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Old 24-01-2019, 02:47 PM
Jasp05 (Aaron)
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The shed only gets a few hours a day of direct sunlight. Its protected in the morning by some large trees on the back fence, and then by the house in the afternoon.

I might try insulating the roof, and have a fan circulate air around. (This was something I had already planned to install but have it on a microcontroller to kick in above a set temp or humidity.)

How hot do things have to be before I should be too concerned? I would like to leave the guide and imaging camera's all attached to the mount when not in use.
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Old 24-01-2019, 04:42 PM
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Aaron if you want to leave everything attached as you have said, you really need to keep the heat to a minimum.

It is good that you have some shade and the Sun is not burning on the roof.

Try and keep it under 30 i reckon, heat can do some serious damage to quality optics.

But that is just me, I am very fussy and protective of my equipment, well when i had it that is.

I have seen at Star Parties people leaving their scopes out in the burning Sun all day without any shade, I just shook my head and kept walking

It would have been 50 plus inside that Scope.

Leon
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Old 24-01-2019, 05:32 PM
Jasp05 (Aaron)
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I'm with you Leon. I'd much rather look after the gear as best I can.

I've got the parts to build a temperature and humidity logger, so I will do some measurements before I put everything in the shed. (It's all kept inside still).

Not sure I can keep it under 30 degrees, but will definitely be trying to keep temps under 40.

Just had a thought of making a "net" out of shade cloth. Make some spacers to put on the roof and sides so there is an air gap. and have it easily removable for observing nights. This with a bit of insulation and air flow inside should do a reasonable job of keeping temps within reason.

Will do some testing in the meantime.

Thanks guys.
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Old 24-01-2019, 10:34 PM
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Marke (Mark)
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I wrapped the obs in sheets of the silver foam core insulation and then lined the inside with ply it's worked very well at keep temps stable and very little condensation ever for 7 yrs now
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Old 25-01-2019, 07:48 AM
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^ A white painted roof is a good way to go to reduce solar radiant heat effects as is (High shade percentage) shade cloth!

If you're building and wanting a metal roof, then white colourbond roofing would be better still. Also keeping your white roof clean will maintain its high reflectively, which is easily lost by dust, dirt and leaves. In terms of reducing any transmitted heat then sure, use insulation (foam sheet seems a good idea) and if you really want it cooler, then close all openings. All though you may want to have a controllable opening with fan to extract warm air/ pressure relief as it slowly heats up and or control any excess humidity as it will over time effect equipment left in place for extended periods.

Best
JA

Last edited by JA; 25-01-2019 at 08:19 AM.
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Old 25-01-2019, 11:58 AM
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Aaron that is a perfect start you would be surprised at the heat difference, put a cheap Bib W 300mm fan in there and just let it run, i used to chuck mine out every six months and buy a new one at that price.
Some heat escape opening/fan would help even more.

Leon
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Old 25-01-2019, 09:21 PM
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Ukastronomer (Jeremy)
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When I did my first one I used this

https://www.homebase.co.uk/knauf-earthwool-loft-roll-200mm_p394101?_$ja=tsid:%7ccid:1641 705554%7cagid:59793718061%7ctid:pla-298659004243%7ccrid:316339754527%7c nw:g%7crnd:18086554136109370262%7cd vc:c%7cadp:1o1&gclid=Cj0KCQiAhKviBR CNARIsAAGZ7CfCW8BLyGUOMrJtaipMLmHsN vStYBLWehcwMtJOe0tjkpEgTGVSodcaAhI4 EALw_wcB&gclsrc=aw.ds


Here was mine

http://www.spacegazer.com/index.asp?pageid=97497
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Old 26-01-2019, 12:05 AM
Jasp05 (Aaron)
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So after logging some temps overnight, the shed topped out at around 40 degrees. around 6-10 inches from the roof itself.

Humidity stayed alright at 50-60% for half the day rising again at night. Still have to seal the shed and throw some dehumidifier stuff in there.

Temps were forecast at top of 31 and 53% humidity.

So 9 degrees above ambient during summer isn't so bad. and if humidity stayed at 50% I'd be happy.


So with a white roof and maybe some shade cloth and a fan I should hopefully keep temps around 5 degrees above ambient. which should only be 25-35 degrees for most of the year.

Will do some more testing once I have painted and sealed things up.

You think a max of 35 degrees and try to keep humidity around 50-60% will be ok?
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Old 27-01-2019, 05:12 PM
gb44 (Glenn)
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I have an idea for the roof that I am yet to try out.
Use the light corrugated plastic sheeting.
Apply a coat of polyurethane gradually across the sheet while gradually adhering a sheet of reflective aluminium. So as to inbed the ali. Cover the ali sheet with a second coat of polyurethane.
The finished sheet reflects sunlight and the aluminium sheet is protected inside the shed. And the roof is lightweight.

What do you reckon?

I suggest the Coghlans Emergency Blanket - aluminised polyester 1.3x2.1m
I bought years ago from BCF for about $10each.
pic attached
Could using cooking foil?

I had a colourbond r/o/roff roof and used 10mm polystyrene foam adhered to it inside. I could feel the heat coming thru but it still made a big difference. I'll likely try 15 or 20mm next time.

Does the foilboard applied on the exterior have adequate longevity?

Cheers
GlennB
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Last edited by gb44; 02-02-2019 at 04:51 PM. Reason: add stuff
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Old 13-02-2019, 09:46 AM
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muletopia (Chris)
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polystyrene sheets

My Take,
One hot day last summer my eye pieces which are stored in a sealed tupper ware style box were still hot after the ob had been opened for a couple of hours and had cooled down. The box is stored in a pod on the western side of my Sirius dome. For an experiment the western wall of the the pod had a cut up piece of packing polystyrene
inserted. Yep, cool(er) eye pieces. So I bought 6 sheets (8ft x 4ft) of 10 mm poly foam.
Silastic was just strong enough to hold the sheets to the curved wall.


This has been successful. I have not taken the temperature in the ob but after a 40 degree day the ob is pleasantly cool but the massive steel pier is still a little warm to touch.


Chris
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Old 17-02-2019, 01:34 PM
gb44 (Glenn)
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The 10mm polystyrene is working then. Are you going to wrap the pier?

My concrete flooring was covered with the plastic board used for real estate sale signs but I see its available in bunnings. Gotta keep everything cool. Great for items that may drop to the floor too.

GlennB
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Old 17-02-2019, 08:32 PM
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For Glenb

No, I do not intend to wrap my gusseted steel pier, As for floor covering,
a soft cover to kindly catch dropped items is good.
I found that an impervious covering placed directly on my concrete floor (isolated from the pier) rapidly became very wet due to the lack of ventilation.
This was solved by covering the floor with Plastics Plus interlocking grid mat squares and laying solid EVA interlocking squares on top of that. Although the EVA was only raised about an inch but this was sufficient to provide ventilation. As a bonus
cutting slots in the supporting webs allowed unobtrusive passage of cabling apart from that in the cast in the floor access channel.





Chris
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Old 30-03-2019, 02:38 PM
appiice (Ed)
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rESULTS

Hello Aaron

Any results?

I have a 3m ally dome that is painted very light blue but otherwise is uninsulated, the attached warm room is white colorbond sheet but insulated, my observation is that the dome heats up but cools quickly, the warm room heats slower but cools slower.


The heat hasn't been an issue for me - I'm in Bathurst, a hot day for us would be 35, it is a rare summer night that the temp' does not drop to the low 20's.

Ed
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