I am adding an auxillery fan to my HVAC. Actually two; One for my
computer room where the computers keep it rather toasty, and one for my
bedroom where the large number of windows keep it rather 'outsidey.'

I want to start with the bedroom one which is already installed in the
duct. I have run the wiring to the furnace area. 3 wires; power and
ground. Wiring nailed into ceiling floor joists, etc.

The question is what to do now? I want to use a relay so the aux fan
comes on when the HVAC blower is on.

So I have a relay that I need to mount somehwere. Its coil will be on
the HVAC control which IIRC is 24vac. Its NO contact will connect from
a switch which will be powered by the main furnace switch next to the
furnace. This is lookin nasty though as it seems I need to install some
connectors on the wires and plug them in, or maybe find a relay with
screw terminals!?

I am assuming this relay needs to be mounted to something and in some
kind of enclosure? I intend to put it in a normal switch box mounted to
a floor joist in the ceiling.

I am assuming the wiring needs to be in metal pipes? Also does the
24vac need a seperate pipe from the 120vac wiring?

Is there a simpler way?

This is a pretty small fan which I believe is 1A load for 120VAC. I'm
an electrical engineer but not an electrician. I don't know the rules
but I'd like to follow them if I can learn them.


--
Respectfully,


CL Gilbert