Windshield Sweating/Condensating

[Dennis12]

Does anyone have an answer for my windshield sweating and running down the windshield onto my dash when I run my furnace.?

[Bumpyroad]

my chieftain had windshield fans and having them on helped some. if all the occupants stop breathing,, it also helps.
bumpy

[darsben1]

DrewE wrote:
This is condensation, and it happens when the inside surface of the glass is at a lower temperature than the dew point of the air in the RV. The solutions are to either raise the temperature of the surface the air comes in contact with (i.e. insulate the glass somehow, maybe with a cover on the outside or drapery on the inside or something) or to reduce the dew point of the air in the RV (by some form of dehumidification, which may be as simple as having better air exchange to get rid of excess moisture).

Note that the furnace operation isn't really involved in the sweating, aside from it being used when the temperatures are cold outside and hence the glass gets cold. An RV furnace does not introduce moisture into the RV unless the heat exchanger is perforated; and if that's the case, it needs to be taken care of ASAP for safety's sake.

No the furnace doesn't but living things do through respiration. Heated air can hold more moisture than cold air. So when the moisture laden warm are comes in contact with the cool window moisture is shed onto the window.

[DrewE]

This is condensation, and it happens when the inside surface of the glass is at a lower temperature than the dew point of the air in the RV. The solutions are to either raise the temperature of the surface the air comes in contact with (i.e. insulate the glass somehow, maybe with a cover on the outside or drapery on the inside or something) or to reduce the dew point of the air in the RV (by some form of dehumidification, which may be as simple as having better air exchange to get rid of excess moisture).

Note that the furnace operation isn't really involved in the sweating, aside from it being used when the temperatures are cold outside and hence the glass gets cold. An RV furnace does not introduce moisture into the RV unless the heat exchanger is perforated; and if that's the case, it needs to be taken care of ASAP for safety's sake.

[darsben1]

I assume you mean when you are parked. When on the road your defrosters should take care of the condensation.
Only "cure" is to crack a window to stop condensation. That has never helped my situation. I put a towel on dash to catch condensation and in A.M. if I am going to be driving I wipe inside of the windshield. If I am staying put I do not worry about it.

[Sam_Spade]

YIKES.

Yes. Have the heat exchanger and flue checked to be sure there isn't a leak somewhere.

Having moisture accumulate inside when a gas heater runs is a sign of flue gasses getting INSIDE the house/trailer.

This could be dangerous.