Thursday, October 16, 2008


This blog has shifted to a new web site called Nomadic Home. Click here to see it.

On a forum that I follow, a question was asked about how to stop condensation. In this particular case there was a problem with condensation forming on the ceiling around the light fixtures of a motorhome.

This was my response.

It would probably help to see why you are getting the condensation problems. Condensation occurs when warm moisture carrying air comes into contact with a colder surface, reducing the relative humidity to the point that it condenses into liquid water.

There are two approaches to this. One approach is eliminating or reducing the temperature differential between the surface and the surrounding air. The second approach is to reduce the humidity in the air. A combination of both approaches is probably going to be the most practical.

Starting with reducing the surface to air temperature. It sounds like there is no, or little insulation around the light fixtures. They are obviously the cold points in your rig. It may be that there is a lack of insulation in that area to reduce fire risk, or it could be that it is just easier to install the light fixtures that way.

If you can fix some insulating material onto the area that is getting the condensation you will either reduce or eliminate the condensation.

The second thing to look at is the air humidity in your rig. Most of it is likely to be coming from the occupants. People release a huge amount of moisture into the air just from breathing. For this reason ventilation is king. It may seem counter intuitive, but keeping everything shut up to keep the warmth in, can will usually make things feel colder, because of the high humidity levels. You should have vents in your camper/RV. Make sure that they are open at all times. If they already are open, then try to keep a window cracked, if possible.

It is also worth evaluating any heating system you may have. If it is run on gas and is not flued externally, it will be introducing huge amounts of moisture into your accommodation.

Also humidity is relative to temperature. What that means is the higher the air temperature is, the more water it will hold in gaseous form. When the temperature reduces, it can't hold as much water in gaseous form and must release some of it in liquid form, usually by condensing onto a cooler surface.

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