Re: PID control + radiant heating

[Steve_88]

I know Darryl Taylor and others did a lot of work coding a pid project for controlling the temperature of a reptile environment. I'm going to be installing radiant heating in my new basement in the next few months and starting to think about the temperature control aspect. I'm interested in using a pic as a controller, does anyone have experience in this area? It is quite new to me (the radiant heating) and pid routines.
Thanks

[HenrikOlsson]

Hi,
I don't have any hands-on experience with radiant heating of living spaces etc. I can't see any reason for it not working with incPID (or any other PID routine) but I think it's going to be a bit tricky (time consuming) to tune considering the slow response of such a large space.

You could go with a phase angle control scheme or a low frequency PWM, depending on the power of the heater and the size and losses of the room a PWM period of one to several minutes shouldn't be a problem.

With that said, a simple on/off thermostat (perhaps with a second sensor outside to provide some feedforward) should work properly if you don't have extremely high demands on a stable temperature.

/Henrik.

[Steve_88]

Thanks Henrik,
I'm sure the temperature will be controlled by an on off action. I'll have just one zone, which when it gets to cold will turn on a calculator pump to bring up the temperature. You're right about the length of time it could take to tune it due to the really slow response time. You read my mind when you talk about an outside temperature sensor providing some input in response to a sudden drop/increase in outside temperature.
Steve