Use of Carb Heat

I'm starting to get geared up for my written test, and was finally reading
[thoroughly] the chapter on systems last night. I was reading about carb
heat and how it works and was surprised to learn that the temperature in the
venturi section could be as much as 50 degrees below the outside air
temperature, and that ideal conditions for carb heat were between 50 and 70
degrees with high relative humidity (stuff you guys all know).

Anyhoo, we went flying on Saturday and it was about 58 degrees out with
1800' broken and 2700' overcast in light mist (looked overcast all the way
to me, but it did lighten up after a while). That sounds like a good
scenario for carb icing to me. We were going to try a mini-cross country to
a local airport, but decided to do some pattern work since we wouldn't be
legal VFR without skimming the treetops, dodging towers, etc....

My question is, in these or similar conditions, would you consider using at
least partial carb heat to help prevent icing, or periodically turn the carb
heat on to clear out any ice that may have formed? Is there ever a time when
you would use carb heat as a preventive measure?


John K.
Student Pilot
Somewhere between solo, X-country, the ground, and space