Dehumidifier

Was in the obs checking for little beasties spinning webs and noticed some mould on the frame of the LX200. None on the optics thankfully. Anyone know where or if I could get a battery powered or 12V DC dehumidifier. Don't really want to run one on AC due to cost (£280 per year is the cheapest I could find) and the fact that I run an extension cable out.

Hi Kieran,
I have a mains one in the dome, they require quite abit of power so I'm not sure you can get a battery version, never seen one.

Have used dehumifiders for approx 15 years drying Kayaking and mountaineering gear. Also good for the scope and mount after a 'wet' night. However I have never seen a DC powered one in the brochures.
As regards costs, freezing water uses less energy than evaoprating water. So work out the cost of heaters to remove that amount of water vs the dehumidifer option.

Kieran,
I think another solution I would suggest if you want to keep away from AC/mains power in your observatory, is to make provision for air circulation. If no air is circulating in a humid enclosure such as your wooden observatoy, then it will be an ideal breeding ground for mould and mildew. Try 2 (or 4) 12V fans, like what you have in a computer tower (they run forever, and take little in milliamps, and are quiet), and place them at opposite sides of your walls -> one side blowing in, the other blowing out. For added effect, place the inward ones at the bottom, and the outward ones at the top (ensuring withdrawl of any risen warm moist air).

I am currently working on this set up for my metal shed which suffers from condensation. Once I have all the gaps filled with expanded foam, I'll add the fans, and work them off of rechargeable batteries. The batteries will be recharged by day from solar cells. The circuit I am using is what you find in your cheap rechargeable solar powered garden lights.

Seanie.

="Seanie Morris"

I am currently working on this set up for my metal shed which suffers from condensation. Once I have all the gaps filled with expanded foam, I'll add the fans, and work them off of rechargeable batteries. The batteries will be recharged by day from solar cells. The circuit I am using is what you find in your cheap rechargeable solar powered garden lights.
Seanie.

Hi Seanie,
I have a very similar metal shed to you, I do get condensation on the inside of the roof, but never enough to drip and form lakes on the floor. I keep the scope in there and the 15w bulb is enough to keep the entire thing dry, without it the mirror fogs over at times. Condensation on the roof is not an issue for it thankfully.

You are correct in installing fans but what you'll find is that you'll want them for a different reason, when the sun is out the metal shed turns into a furnace so what I did was install a thermostat that activates 2 high power mains powered fans to keep the shed from not getting to hot.
Warm air+cooler optics = dew on optics. Metal sheds cool rapidly in the evening but also heat rapidly when the sun comes out in the summer.

What I'm also considering is lining the outside roof of the shed with something like tinfoil which will reflect most of the sun heat and keep the shed from getting warm, but this is rather drastic, so we'll see how it works out this summer.
Wooden sheds have the same problem but do it at a slower rate.
Interestingly enough, the white dome does a fantastic job with heat and dew, alot better then the metal shed.

Got a response from one of the manufacturers. Apparently the 12V DC versions exist but they have so little power that they are only of limited use. As for circulation within the shed, standing in it on a windy day suggests there is enough ventillation. Of course it is just ventilating moist air from outside. Sourced an AC one which costs about 2p per hour and I will stick it on a timer.

Mate of mine has a white dome and he says that the roof was covered in condensation one morning and has had to stick in a dehumidifier.

The problem might be the scope coat trapping dew on the scope. I always stick it on after a session. So I might look at leaving it off tillall metal parts have dried out the next day.