Adding Controls to start of starter circuit

[Journeymanjoe]

Hi All,
First time question here. I do some electrical maintenance at a small local fire hall. Unlike many standard fire halls, this one does not have truck tailpipe exhaust in the truck bays. They count on the guys hitting a start button on a starter at each overhead door before leaving for a call to start the exhaust fan system. They are very budget concious and looking for an economical fix other than tailpipe exhaust. My motor control is a bit rusty, but could I install a limit switch at the top of the overhead door rail and wire in parallel with the start button?

 

[LarryFine]

My motor control is a bit rusty, but could I install a limit switch at the top of the overhead door rail and wire in parallel with the start button?

Welcome to the forum.

That would work to start the fan, but how is the fan normally stopped? The door would keep it on.

You could disconnect the starter's latching contact, so the fan is started and stopped by the door switch.

 

[Journeymanjoe]

Welcome to the forum.

That would work to start the fan, but how is the fan normally stopped? The door would keep it on.

You could disconnect the starter's latching contact, so the fan is started and stopped by the door switch.

Thanks for the reply. The starter setup has a built in timer. The fan times out after 10 minutes I believe. I was hoping to find some type of momentary contact limit switch

 

[jim dungar]

Maybe mount your limit switch at a level where the door goes past it, rather than stopping on it. This would give you a momentary contact close. You can then look at a lever mechanism that operates in one direction only.

 

[ptonsparky]

Or change the timer to 5 minutes and let the fan run at open or close. Running while closed may cause an issue with back draft of truck bay unit heaters.