I have used these electric auto drains with good success.

[Linked Image from grainger.com]

They did not clog up in a very damp and dirty environment.

If you must build your own I know timers that will work but they are not inexpensive. $100 - $200.



[This message has been edited by iwire (edited 09-02-2006).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts