Which is worse for electronics in the summer Heat or Humidity?

[cdev]

What is worse/better for my electronics equipment and parts, in the summer, being stored in a very hot upstairs area where AC is only on when I am there, or being stored in a basement which gets humid enough to cause problems on copper PCBs if etched and not coated. Climate is hot and usually very humid summers. The basement gets particularly humid if we dont run the dehumidifier full blast which gets noisy. central AC of the whole house would probably be too expensive. We generally do okay on our ground floor using it very little, but there isnt space on the ground floor for a bench. I am sure a lot of us are in this situation, how do you handle it?

 I'm worried about, for example, the caps in my older Tek scope drying out. It can be extremely hot up there (over 110 degrees F on any fairly sunny day unless I open both windows and skylights and have a fan in one blowing out and another one blowing in, or have the AC going full blast.)

I am less worried about the winter..  Spring and fall are nice.

[Gyro]

I would say very high humidity is going to be much more of a killer than dry heat.

Even at 110'F (only 43'C) you're at a low proportion of the Electrolytic capacitor temperature ratings, and probably well below their temperature when operating.


P.S. Worst of all... Hot humidity, that's where you get fungal growth and accelerated corrosion etc. This is the domain of 'tropicalised' equipment.

[edpalmer42]

I think that for equipment being stored, humidity would be worse than heat.

Your situation of high heat and humidity is the worst of both.  The high heat does tend to limit condensation which I think is the real problem with humidity.  Humidity without condensation doesn't seem like much of a problem, but I could be wrong.  Condensation will cause corrosion that could cause both cosmetic and functional damage.

On the other hand, heat of 110F isn't significantly different from the internal operating ambient for lots of equipment and while being stored, there are no hot spots that need fan cooling.  Also, remember that most equipment and components have higher storage than operating temperature limits.

You might consider basement storage with a dehumidifier.  They draw power similar to a small air conditioner, but are self-contained so it's trivial to set one up.  Your central air conditioner also does dehumidification so you might just have to rearrange some ducts to accomplish the same thing without buying a stand-alone unit.

[schmitt trigger]

Seeing the large airplane storage facilities located in the southwestern US deserts, I would think that a very hot but very dry environment would be preferred.

[Kleinstein]

If not used very often one could consider a closed container and some dying agent. So the box could be in in the humid basement and the parts still dry. It is relatively easy to keep water out.

Even some 50 C should not be a real problem for electronic components. Even in the normally hot room they may be condensation at night of not isolated. So one may still need some suitable box - painted cardboard could be good enough.