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Palpater · Joined: 19 Feb 2008 Posts: 1 Location: NH

I have a vent fan in my greenhouse. Currently, I have one timer activating the fan and the lights. The fan must be on when the lights are running.
I want to add a second timer to activate only the fan during lights out periods
for incremental ventilation throughout the dark periods.

Can I do this?
One live feed (110 US circuit), two separate timers, feeds from each of the timers wired to the one fan input.

I am concerned that a condition could exist where both timers might be on at the same time. Would this create a short or a loop in the circuit? Would power from one timer go through the fan and damage the other timer when its off?

What is the best way for me to provide power to the fan from either or both of these timer switches?

Thank you for your help.

vince knight · Posted: Tue Feb 19, 2008 11:27 pm Post subject:

Why not run a timer for the lights and a timer for the fan?
You can set the fan to be on when the lights are on and to run when you wish in the dark periods.

Vince

b · Posted: Wed Feb 20, 2008 3:24 am Post subject:

I agree with Vince. Wiring as suggested initially would backfeed the first timer and the lights would be intermittently on through the backfeed from the fan. You could check with the manufacturer to see if they have any electronic based switching assemblies that would do that for you.