[tomob1]

HI,
I have a self contained heating/air unit mounted outside the house.
Everything runs fine but was getting hot and cold spots inside.
Mounted two in duct fans to"push" the air to all registers evenly.
I want to wire it to the unit blower so they all come on at the same time.
At the unit blower the blue wire is hot, a brown and a purple wire make the condenser circuit, and the red and black wires don't seem to do anything. There's no amperage through them when the blower is running.
There is a red wire in the thermostat, no blue or black.
Is the black wire neutral? Shouldn't the neutral be carrying some current?
BTW everything was checked with an induction type meter set to amps.

Thanks!
Tom

[hvac1000]

Find the circuit that activates the outside blower that pushes the air inside and use that circuit to activate a relay. Then wire your inside little helper fans to the relay. CAUTION usually the outside motor uses 220 volts while the little helper motors is 120 volt. This is something that has to be done on site but I can give you a hint. You will need a relay with a 220 volt coil.

Follow all wiring practices according the NEC. National Electric Code for your safety.

[KISS]

As stupid as it seems, you can use one of these: http://www.ssac.com/catalog/TCS01A01.pdf

Jusp place it around one of the power wires going to the unit. You now have a solid state contact that can operate the fans.

[hvac1000]

Very cool little tool. I have never used them before. I guess I am from the old relay school. I kept a copy and will contact the mfg for a few samples for my class at the university. Nothing like a new toy.Thanks for that post KeepItSimpleStupid.

[KISS]

Cool. You liked my rabbit!

[tomob1]

WOW! You guys are great!
The unit is 120v, would I still need to wire a relay if I go that route?
How about that solid state gizmo? Are the two blade contacts (#'s 1 and 3) my hot and neutral? Do I negative or positive switch it?
Thanks for all the help. And thanks for not making fun of me for a dumb question!:)
Tom

[KISS]

Reading your post, I'm a little confused. It appears your trying to find current in the t-stat wires. You won't. It's too small.

The next part is that I/We have no idea of the booster fan voltage and/or current. We can assume 120 VAC and small current.

We also have no idea of the distance between the furnace and the booster fans and whether you'd be willing to run 120 V wire to these fans. Assuming it is 120 VAC.

So lets re-cap. One of the main power leads of the furnace would go though the little hole in the device.

Terminals 1 and 3 are a solid state relay. Protect it with a 1 amp fuse and a disconnect/(switch) on the 1/3 switch side.

So if the current is below 1A, that's 120 W and I'm sure it is then powering the fans direct is OK. You could make home runs or parallel both fans together. And run the parallel combination back to the furnace.

On the more complicated side, but it could be a better choice because of your situation.
You could use 1 and 3 to switch a 24 VAC circuit from the furnace, Same 1A fuse and switch and use smaller solid state relays at each fan and the fan power which probably is already in place.

You could use one of these ssR330AC10 at each of the fans or wire the both fans together to one of these relays. http://www.omega.com/Temperature/pdf/SSR330_660.pdf
This relay would use a switched 24 VAC signal and turn on the fans.

You have options. There are tradeoff's.

One may be easier to troubleshoot then the other. One might be less expensive.