How do you demist windscreens?!
Discussion
Ok, I'm confused.
I always thought that condensation on a windscreen was due to temperature difference. So now in winter it's when you get in your car and the body heat causes condensation on the inside of the windscreen, because of the cold outside. Vice versa in Dubai, where you get condensation on outside of windscreen because air-con inside is so cold.
Right?
Ok, so WHY does the "nuke from orbit" buttons on Mercs, Fords etc (the blast-the-windscreen-as-it's-misty button) give out hot air?
Also, my bro said to me the other day when trying to demist a screen he uses hot air to do it, not cold. I'm confuuuuuuuuuuuuuused!
So, what IS the demisting process?! (no flash quick-clear screens here please people, you Ford drivers!).
I always thought that condensation on a windscreen was due to temperature difference. So now in winter it's when you get in your car and the body heat causes condensation on the inside of the windscreen, because of the cold outside. Vice versa in Dubai, where you get condensation on outside of windscreen because air-con inside is so cold.
Right?
Ok, so WHY does the "nuke from orbit" buttons on Mercs, Fords etc (the blast-the-windscreen-as-it's-misty button) give out hot air?
Also, my bro said to me the other day when trying to demist a screen he uses hot air to do it, not cold. I'm confuuuuuuuuuuuuuused!
So, what IS the demisting process?! (no flash quick-clear screens here please people, you Ford drivers!).
StuB said:
Hot air heats up the inner surface and reduces the tendency of the moist air to condense.
Even better is to blast with hot with air con on as that dries the air as it blows up and clears the car fastest.
Even better is to blast with hot with air con on as that dries the air as it blows up and clears the car fastest.
That's how I do it - the speed of demisting always impresses friends that don't have air-con in their cars.
Is it better to press the recirculating button as well to prevent more damp air bring drawn in from outside?
Philbes said:
StuB said:
Hot air heats up the inner surface and reduces the tendency of the moist air to condense.
Even better is to blast with hot with air con on as that dries the air as it blows up and clears the car fastest.
Even better is to blast with hot with air con on as that dries the air as it blows up and clears the car fastest.
That's how I do it - the speed of demisting always impresses friends that don't have air-con in their cars.
Is it better to press the recirculating button as well to prevent more damp air bring drawn in from outside?
I just clicky the heated front screen button
StuB said:
Hot air heats up the inner surface and reduces the tendency of the moist air to condense.
Even better is to blast with hot with air con on as that dries the air as it blows up and clears the car fastest.
Even better is to blast with hot with air con on as that dries the air as it blows up and clears the car fastest.
Spot on. Both AirCon or Heater on Max's main impact is that they dry the surface. So blowing warme but dry air over the surface will be best as the warm, dry air can hold more evapourated moisture.
Warming up the screen will enable you to prevent it from continuing to mist up.
That's why blasting air, either hot or dry (aircon) clears a screen quicker than embedded heating elements.
TonyHetherington said:
RTFM tony said:
(no flash quick-clear screens here please people, you Ford drivers!).
Ford - wash your mouth out mr!
Hot air is the one required - a hot windscreen will not condense the water droplets on it.
Of course any moving airstream will do to evaporate the water on the screen, but making the screen warm helps even more to keep it clear.
I've found in general having used many products to demist windscreens in my MG, that none of them work very well. Best thing is a chammy leather in the footwell for when you need it!
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