Stopping condensation?

[ChrisM]

Condensation is forming on the underside of my observatory's sheet-metal sliding shutter.

Does anyone know of a material that I could apply to this surface to reduce the effect? A spray-on solution would be neat.....

Cheers,
Chris

[sheeny (Al)]

G'Day Chris,

The sheet metal is always going to supercool under a clear night sky, which will nearly always cause condensation underneath. You need a vapour barrier - something to stop moist air reaching the sheetmetal to condense. In a house, sisalation (that silver foil under the roof) does this job, sometimes with insulation as well.

If you can use sisalation make sure it's sealed all the way around with aluminium tape.

If sisalation doesn't suit, you could try gluing say 3mm insertion rubber sheet to the inside of the shutter with contact adhesive. This will act as the vapour barrier and insulation combined.

Sorry can't advise on any spray on stuff...

Al.

[pmrid (Peter)]

Originally Posted by ChrisM

Condensation is forming on the underside of my observatory's sheet-metal sliding shutter.

Does anyone know of a material that I could apply to this surface to reduce the effect? A spray-on solution would be neat.....

Cheers,
Chris

I've used a contact adhesive to fix roofing insulation to the roof and walls of my obs. The insulation I have used is a double-sided aluminium box that has a gap of about 25mm between the layers. No more condensation.
Peter

[Wavytone]

ChrisM, what colour, material, and exterior surface finish is on the exterior surface ? This has a lot to do with why it supercools at night. There is for example a huge difference between a white aluminium-clad surface vs zinc galvanised steel, vs composites or wood.

[Lester]

Interesting thread; as I have a unlined colour bond observatory and internal condensation hasn't been a problem yet.

Chris do you get condensation even when the observatory is closed or only when it is open?

[ChrisM]

Thanks for the replies and suggestions.

The dome itself is plywood - white on the outside and black inside. The building is clad with white mini-orb, and insulated for the most part. I haven't had any condensation to speak of on the inside of either of those surfaces.

The shutter is new and is a single layer of "sign white" (standard material for sign writers, I understand), which is about 0.5 mm steel that comes painted white on both sides.

I have some spare sisalation that I could try, but I may also chase up the type of insulation that Peter used.


So far, I've only noticed condensation on the shutter when the obs is closed, however, it is what may be called well-ventilated. The shutter is not at all a "tight" fit, which may have its pros and cons. In hot weather, I expect that the heat will not build up quite so much.

Cheers,
Chris

[pmrid (Peter)]

Would you like a photo? When the rain stops enough to avoid the risk of drowning at the back door, I can swim over to the observatory and take one.
Peter

[ChrisM]

Peter - a photo would be appreciated thanks - but at your dry convenience!

Chris