Cold Weather - Reducing RV Condensation

Reflectix in the windows

 

 

With the departure of Winter and arrival of Spring we will continue to experience cool to cold nights.  To reduce heat loss at night and improve comfort there are some things we can do. A side effect of cold outdoors is condensation on windows. We have trekked and camped overnight down to near 0 F with minimal or no condensation issues. Here's how we avoided or minimized condensation.

Most condensation in our Roadtrek occurs on the glass surfaces. Class B RVs have a lot of single pane glass windows, which have almost no insulating properties. I understand the R-value is about 0.1.  For comparison, the R-value of a sticks and bricks house with 3-1/2" fiberglass batting in the walls is about 14 if the total wall construction is included in the rating.

Without getting into all of the science, the condensation occurs when the humidity in the interior of the RV is above the dew point temperature of the glass windows or other cool-cold surfaces. Normal comfort humidity in winter and cold spring nights will be above the temperature of single pane glass window and condensation will occur. That condensation may freeze on the windows, or just drip.....

In the winter the problem we have is adding moisture to the air inside the RV.  Cold surfaces condense moisture that is in the air. IMHO the solution is:

1. Reduce the moisture released into the air in the RV,
2. Improve the insulation on cold surfaces and the primary offender is glass windows which have almost no insulating properties,
3. Vent excess moisture via a fan, but that also vents heat, so it is my approach of last resort. 

Where does that moisture come from? When we exhale our breath adds moisture. So does cooking if steam is released, and burning propane on that stovetop does the same (a byproduct of burning propane is water vapor).

To reduce moisture release into the interior of the Roadtrek I don't use the stove top which uses propane. There is an added bonus as I then conserve propane for the hot water heater and the furnace.  

I use alternative electrical resources for cooking and avoid using propane; I add insulation:

1. For cooking, I use the convection/microwave and an induction portable electric burner with cast iron skillets, etc. When cooking I keep a lid on it to reduce moisture release into the RV.
2. For boiling water we prefer the microwave.  It heats faster and releases less water vapor into the air. 
3. I add insulation to the windows. I use pre-cut sheets of "Reflectix" on all of the windows. This not only reduces condensation it makes the van more comfortable. It is possible to use two thicknesses of Reflectix in the sleeping area. When travelling in winter we roll up the cut sheets and store under the bed. 
4. As a last resort I use the rooftop vent fan to vent moisture laden air. However, I avoid that because it not only vents moisture, it sends that warm air into the outside. That warmed air is replaced by cold outside air which gets in via door seals, etc.  That cold air needs to be heated with energy.

We have done the above at temperatures near zero F and we generally don't have winter condensation issues....

  Original material http://roadtrek210.blogspot.com/