Try using a digital watt hour meter.
They are basically a digital amp meter.
If fan is running, it will draw current.
If not running it draws no current.
Such meters are cheap and readily available.

 

Attic fan or exhaust fan?

They should be able to tell if the attic fan isn't working by the fact that it is hot!:laughing:

A few of the Auto shops I do work for have exhaust fans to cycle the air out of the pits, they have audible alarms that go off when the power fails to the exhaust fan. Not sure if that is what they are looking for, but if CO gases are a concern, that is the way to go.

 

Hang some toilet paper by the vent in the ceiling.

 

ha, ha! this is an attic vent, wont be a hole in the ceiling

 

A current sensing relay? A sail switch?

 

http://www.amazon.com/CR-Magnetics-Remote-Current-Indicator/dp/B006K3O1MY

 

Differential pressure switch

 

That is what I was thinking, some kind of watt meter.

And maybe a power light wire running to the load side of the fan, if possible.

 

Simple current sensing relay.


http://www.amazon.com/Aprilaire-51-Current-Sensing-Relay/dp/B000XM4BB4

 

Just put the pilot light on the load side of the controlling device but before the load itself

 

Does it use a separate temp switch ?
If so, just wire in a neon light across the contact.

 

Just put a sail switch in the air flow on the exhaust side of the fan to light an LED. A pilot on the load will tell you if there is a load but not if the fan is actually spinning (found that out in an RTU once! Light was on but unit was going off on high pressure because fan came loose from shaft)

 

Most sail switches would require too much space for typical exhaust fans.

 

What kind of sail switches are you using? Mine are maybe three inches long including the switch. I use them in 3 to 24 inch ducts. An attic fan can't possibly be smaller than 3 inches can it?

 

Sure can, I've seen many that don't have 1 1/2" clearance clear from the blade. Ducted is a fish or a different color. I do agree that a sail switch is the easiest proof the fan is actually running.

 

This one will work in a 2 inch diameter opening

 

What type enclosure do you use to mount that and encase the connections in a code like manner ? I have used enclosed units like this Honeywell:

http://thumbs3.ebaystatic.com/d/l225/m/m7ytHiSiuevP2_oZb2hP3CQ.jpg