allanhurst:
Where are you measuring the temperature? There will be gradients.You cannot hold all this enormous volume to a close limit unless you have large circulating fans.
Allan.
I would agree that this space should have multiple sensors. but the volume of air for one unit of about 600 CFM would keep the room air stirred up.
the control sensor should be in the return duct as that would be near the ceiling and the warmest part of the space.
It sounds like a refrigerated walk-in box. not sure what other type of room would have the need to be 1 deg C
I hope it is not fresh food storage, too close to freezing and letting the temperature to have such a huge swing (in food terms) would not stop the food from ripening.