Relays, transformers, actuators and a differential controller

[nlaham]

I have a uniquie project I am working on and was wondering if someone could tell me how it would be possible to control a mechanism using my current controller.

Right now I have a differential temperature controller that uses two sensor probes and turns on and off a 120V relay switch if the conditions are met. The output is normally used to provide power or cut power to a pump, but I want to use the output for something a little more complicated if possible.

I have an actuator motor that turns a valve. When supplied with 24VAC it will activate the motor. When supplied current in the other direction, it turns back to the original position.

How can I use the output of the 120V relay to turn the valve when the controller outputs power, and turn the valve back when the controller cuts power.

I thought if I use a transformer to provide the valve 24V to a double throw relay, and have my relay coil wired to the 120V output. Then when I give power to the relay, I have 24V in one direction, and when I lose power to the relay, I have power in the other direction. Only problem is, then the actuator valve is always drawing 24V. I'm not sure if it is designed for this, or if I'm supposed to cut the 24V after the valve turns.

Any ideas? I am pretty bad at electrical design.

 

[dlgoff]

You could use a couple of Limit Switches

http://www.ustudy.in/sites/default/files/limit_switch.jpg