Now a days with such low cost microcontroller boards it sometimes makes more sense to just wire in the sensors as analog input voltages and control things with either PWM or digital on/off output control using relays or power logic level MOSFETS. It allows one to change parameters and control strategies easily then redesigning the hardware each time a change is needed or contemplated. Just a thought. Dedicated control modules work also and you don't have to learn a programming language.
Here is an an example of a inexpensive digital control board.
Hi Guys,
Great to find this site.
This is exactly what I have been looking for.
Which drawing works as I want to build 2 of these.
1 for a solar hot water project
2 for extracting hot air from attic down to a laundry room
Any help greatly appreciated
Maurice