Getting my head round the condensation thing.

[artie]

It appears to me in very simple terms.

If you have a solid object and the air around it is 4-5 deg C higher than said object you are likely to get condensation on it. The amount of which is dependent on the humidity of the air.

If you can put a barrier between the air and the object so that the air to barrier temp difference is 2-2.5 deg C and the temp difference from barrier to object is 2-2.5 deg C then you will have no condensation, hence the popularity of insulation.

If on the other hand, you brought the solid object temp up to within a couple of degrees C of the air, there would be no condensation.

Anything wrong so far.?

 

[Jacob]

Wrong. The "dew point" temperature depends on the humidity of the air. Your 4 or 5 º difference may or may not bring about condensation depending on the humidity of the air to start with.
Look up "relative" and "absolute" humidity and "dew point" etc

 

[artie]

But surely it doesn't matter how humid it is if there is no temperature difference.?

 

[Doug B]

http://www.dpcalc.org

 

[artie]

http://www.dpcalc.org

Had a play with that and at the present humidity levels it's kind of close to what I was saying.

 

[mouppe]

In my workshop I've never had any condensation at all. It can be -20C outside and +20C inside and not a drop. Windows are all single-glazed. But the room is draughty and I have no humidifier in the workshop so the humidity changes just like outside. Heating is with a radiator and an electric baseboard.

At home condensation can be a small problem but only on the windows at the north-facing side of the house. Very well-insulated house , humidity set to 35%, double-glazed windows etc. Forced air heating.

My experience suggests Jacob is right. By the same token, I can wear a sleeveless jacket when it's a sunny day and -5 C here, but if it's a damp day in Manchester I'll feel cold even when it's +10.