"I don't want this to be too complicated, but needs to be 100% reliable."
That's hard request to fulfill. :)
I think you have good start with what you have so far with the if then else ladder structure. The hardest part of most of the forms application I do is not the functional part but the UI, what the user sees and how they interact with it. From what I understand ladder programming in C# is not the easiest thing to do,
example[
^].
I would start out by creating classes that represent the devices you wish to control with something like the class below that provides an interface container for the logical functions you wish to control.
public class BlowerType
{
public bool on;
public DateTime StratTime;
public DateTime EndTIme;
public Int16 spped;
public Int16 Temperature;
}
Then I would create an instance for each device and dynamically populate a form with the available interfaces where the user can select or add a device and set it's attributes. As far as how to transfer these functions to the code you already have, I couldn't tell you.
Good luck.