Extreme Dew Condition

[Aripaule]

hi,

My Allsky is installed near a small river and as a result, at night it suffers from a lot of dew.

I researched the anti-dew solution offered, but I don't have any knowledge to assemble that circuit. Then I used lens warming strip (lens dew heater) around the dome.

However, on the nights of testing I noticed that dew formed inside the dome, and even with the dew heater turned on the dew was still there. I then decided to open the box to see what was inside and to my surprise the dew heater was completely soaked in water. I then believe that the water was evaporating from it and lodging inside the dome, could this be the problem? If so, how could you resolve it?

I installed a fan at the bottom to try to circulate air out of the box. Could it help? Should I leave it flowing in or out of the box?

Any help is very welcome.

Thank you all!

Some images for reference:

(fan at the bottom)

(dew heater lateral view)

(dew heater front view)

[Aripaule]

I also got great results when the dew didn't affect the images, thanks to the entire project team!

[aaronwmorris]

Exhausting air with a fan means you are also pulling in fresh air.

In your situation, your box probably needs to be both air tight and water tight. If you have air exchange with the outside, being so close to a water source, you are allowing very humid air inside the enclosure.

[Aripaule]

Hi @aaronwmorris,

Before I installed the fan, it was completely (or almost) sealed from the external environment. The only air passages could be between the connections (I can solve this with some kind of glue).

Do you think that just these tiny gaps are enough for the interior to become saturated?

and do you think a fan in exhaust mode (pulling air from inside to outside) could alleviate this effect?

[aaronwmorris]

You may have to caulk all of your connection/junctions. I usually build my enclosure using junction boxes, so I have cable glands connectors off the side of my enclosures (not on the bottom). I even caulk/silicone where the connector touches the side, I silicone all of the screw holes (usually on top) even if the box has a rubber seal.

You may also want to silicone/caulk your bolts on top. While you have a good gasket around your dome, the bolts extend underneath and water can seep through the bolt threads. Its not "likely" but its possible.

Because I live in a more humid climate, I not allow any air exchange. This is also because of bugs, dirt daubers and ants are invasive. I also always assemble my systems indoors, where there is air conditioning, to keep the RH of the air inside dryer.

When I say "air tight" I really just mean no open airflow. The system is NOT going to be hermetically sealed, so over time, air will exchange between the outside. Eventually, every 6-12 months, you are likely going to have to perform maintenance anyway.

[Aripaule]

I think I managed to solve the problem. I attached a dew heater and a mini fan to the system..