Dear Sir,

Commercial Manual Reset Freezstat application, unit shuts down and preheat valve full open. But some say chill water valve shall open too? Skeptical.

Please help feedback appreciated. Pro/Con's for the units mentioned, they have preheat coil (some steam, some hw coils) and CC in main unit, no reheat at unit:

1) Rooftop AHU's that have SF and RF that serve VAV's.

2) AHU's that have SF and RF that serve VAV's in mers.

3) 100% OA Units. Supply Fan no return. Just exhaust in space to supplement for not having return.

Respectfully need your expertise and experience,
Bob C