Problems related to steam preheat valve

Any tips for tuning/programing steam preheat valve. Have seen common issues overheatting, then closing down, then outside air tripping freeze

Verify response on the valve (% open) and the temp response (delta T) is roughly linear, can be tricky if steam heat. Check zero is correct and not an extended signal range.

I always find that most heating coils are oversized so heating valves are very rarely more than 30 - 40% open even on the coldest days. That means there is a section of the coil that’s not active and even if your maintaining the right temp, the freeze stat may still trip.

In these cases, slow is better. I would probably guess the prop band should be no less than 30°F and then slow integral input.

If the freeze stat trips during the transition from unoccupied to occupied you do something to help the process like waiting for temps to stabilize before opening the oa damper.

You can also put a low limit on the mixed air temp (if so equipped).