Honeywell XL15C Flex PID

[man from trane]

I'm new to this controller, and trying to figure out the PID tuning. Honeywell's Help file in LonSpec could not be more vague.

Simple question: What does the Integral Time in Seconds refer to? Is that how often it adds the offset error? Is a lower number going to give a faster response? What are some typical values you would use for a Space Temp Control Loop?

Thanks!

[ascj]

The Integral Gain (also called Integral Time) determines how much impact the error-over-time has on the calculated output signal. It's not how often the Integral Error is added to the calculated output.

The Integral Error is constantly being added to your Proportional Error to make up calculated output signal. Your Integral Error is the constantly running sum of your Proportional Error divided by your Integral Gain (also called Integral Time).

I attached a page from a CVAHU, that shows some default PID settings-
Default PID.pdf

But the CVAHU uses Control Bands. Where as the XL15C uses Deadband(Percentage of Throttling Range) and deadband delay.

[man from trane]

Thanks ascj! That's exactly what I was looking for. I found that an Integral time of 300-600 seconds (depending on equipment sizing) with a TR around 3 gives decent space temp control.