I then decided I could put the air conditioner in the basement, couple it to a blower and force air into the existing ductwork. The air will be then able to travel up to the attic, or into the other ductwork int the rest of the house. I figured I could have some control over how much goes to the attic by restricting flow past the first Y which goes to the attic.
So I adapted a blower , and coupled it to the air conditioner. I extended the wire on the heat sensor so it can go in the attic. I was considering moving the whole control panel to the attic so the remote would still work, but after lookingat how the unit is wired , it isn't easy to separate the electronics controls because the relays for the fan ,pump etc are on the same board which means I would have to run the AC wiring from the control box to the unit, this wasn't feasable.
so I came up with a new plan, which is to use a remote control extender to re-broadcast the remote control signal to the front of the AC unit. these are commercially available. I will live without being able to see the display, and go downstairs if I need to look at it .
The only other modification , other than extending the heat sensor , is that I want the blower to switch on along with the (3 speed fan) in the AC unit. the unit has a power saving mode and it would be nice if the blower could switch on and off along with the AC's 3 speed fan.
I don't want the load of the blower to come from the AC unit, so I was planning to use a 110V relay powered from the same wires supplying power to the AC unit's fan. , so the coil of the relay needs to be 110 and it just uses a bit of power to work the relay's coil. this would be a negligible ammount of power so wouldn't load the AC's circutry.
The blower is 110V . I can run the power wire to the blower through the contacts of the relay and that would work. The control cable would be carrying 110 and I don't know if that would comply to code or not. The other option is to use a small power supply to run a second relay at the blower, then the signal wire( through contacts of the added relay in the AC unit ) could be 12 or 24 V. this is a bit more complicated as I need a second relay and a 12 or 24V power source.
Which method of swithcing the blower on and off would be more acceptable? does it matter if the control cable carries 110V? would a relay be best or some sort of SCR?