Also to conserve wiring space, I have gone over to using TR64 instead of TEW as the OA dia. is greatly reduced, still 300v rating.
Its a bit harder to get, but when you have a bundle of 20 or 30 wires, it makes a difference.
CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).
“Logic will get you from A to B. Imagination will take you everywhere.”
For a bare bones PLC try www.trolsystems.com Kind of like PLC for dummies. Not fancy but easy to program. Use some digital temp controls from e-bay or PPEs budget catalog. You got a control for around $1000 or less.