TheSkySearchers

In my roll-off roof observatory, I'm getting some mildew on wood and corrosion on metal parts of my equipment (such as counterweights). There are no leaks or water getting inside, but the wooden obs is unlined apart from building paper. It is not tightly sealed - there are the usual areas for air to get in and out. There is no permanent power supply to the obs, so a dehumidifier is out of the question, especially as it is not sealed in any case. Does anyone have similar problems, or solutions?

This article might be of some help: http://arksky.org/aso-guides/aso-genera ... re-control.

Dave

Good moisture guidance there Dave. The bit I did not understand and could someone explain please, was from this bit,

"This problem is FAR more common in summer than in winter. In winter I
suggest a small 1000 watt or less space heater or 200 watt lightbulb being
left on during closed periods to minimize humidity. If you are able to keep
the inside temperature to within ONE DEGREE of the dew point on all exposed
surfaces, you will prevent condensation from ever forming within your
observatory."

My plan was to have an Arduino turn fans on when the temperature got too hot and turn heaters on when too cold with a view to keep the temperature within a range and above the dew point. So why does the above say to keep the temperature to within 1 degree of the dew point to prevent condensation?

Thanks

Our OP's problem is that he doesn't have power in the observatory, which makes running heaters, lightbulbs or dehumidifiers a problem.
Without power, the only thing I could suggest is leaving it more open to airflow if that is an option when the weather is appropriate.

Rasalgethi wrote: ↑Fri Sep 09, 2022 6:03 pm So why does the above say to keep the temperature to within 1 degree of the dew point to prevent condensation?
Thanks

To prevent condensation forming you only need to stay 1° above the dewpoint, as long as you can maintain a temperature above the dewpoint condensation cannot form.
If you have no power available have you considered a solar panel?

Have you tried hanging a large towel over your equipment? It works for me, at least sometimes. Maybe because it keeps the equipment a bit from cooling down, or maybe because it retains warm air that wants to rise.

It might be true, I just searched and found this reference, FWIW. I also read that you can put a towel over your windshield to prevent frost, another example.