home-made arduino weather station condensation/frost vs ventilation for heat

[William Garber]

I created a home made arduino weather station and the software is running okay; the temperature gets up to 110 F on the hottest day on record and it is usually dry except for the rainy season when it can pour mercilessly; the system is made of four enclosures which are currently waterproof and are shaded from the sun; I am waiting for a hot day to find out if they will overheat; If I introduce a tiny covered vent I am afraid that will let in condensation which will freeze on a frosty day and damage things;

any input please?   Should I leave it waterproof or add the vent?

The dev board is an adafruit itsy bitsy M4 (ATSAMD51G)

[William Garber]

it has weewx drivers

[Timothy L]

In my humble opinion having built a couple boxes for wireless bridges to shield the radios from rain, the more venting the better. As much as possible to cool the equipment and in your case avoid condensation. I glued styrofoam board to the metal roof to reduce heat from the sun while leaving bottoms open with wire screening to prevent bugs and let moisture out. I also put 2 inch holes near the top with screening to let heat rise out of the holes while fresh air comes in. I wouldn't put a temperature sensor inside the box due to the fact that you are readings will not be actual outside temperatures but box temperatures.

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[Tom Keffer]

I agree with Timothy.

After a career in oceanography and 20+ years of sailing, I've concluded there is no such thing as waterproof. Just varying degrees of water resistance. 

Condensation happens when warm, moist air meets a colder surface and gets chilled to the dewpoint. Ventilation ensures that everything is at the same temperature. I  don't know how much heat the M4 puts out, but it's probably enough to keep the surfaces warm relative to the incoming air.

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[William Garber]

this is a continuation of
https://forum.arduino.cc/t/will-adafruit-itsy-bitsy-atsamd51-overheat-in-enclosure-at-110f/1045678

[Anton vanNwnhzn@GMail]

Based on my experience with naval equipment, real watertightness has a high price.

As alternative,  the more ventilation, the better:
just try to prevent that drops, dust and insects may enter the box.
The protecting box when able to 'breath' probably can get rid of condensation.
That said, you should accept (trading off price against protection) that most lower priced electronics have insufficient protection against moist and as consequence will have a 'limited' lifetime.
Therefore plan ahead a replacement or repair max. every 3 years.

Op 9-11-2022 om 15:17 schreef William Garber:

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[William Garber]

lecoqacr...   There is a temperature probe in a solar radiation shield and another temperature probe inside the enclosure to see if it is overheating.  It gets very hot in the summer and it goes down to freezing about now in the morning when there is an occasional frost.

There is a second weather station which has vents covered with fans.  that seems to be doing okay now.  it has not crashed once !!!!

[Timothy L]

I would like to reiterate from the first email as well as what Tom had stated that a lot of ventilation would be your best friend in your situation. The more the better. Your main concern should be simply keeping the rain off of the Electronics but use a lot of ventilation. Solar powered fans may help. Your enclosure should stay as close to ambient temperature as possible. That is the ideal of what you would be able to hope for when it's sunny and hot.

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