Pneumatic freeze t-stat set-up on an airhandler?

[joetbear]

Looking for the best way to set-up a pneumatic freeze t-stat on our airhandlers, that uses 100% make-up air. We have an older energy management system and is hard to modify for winter weather. We are looking to put in a simple pneumatic t-stat in the system. Any suggestions?

Airhandler is two coil (heating/cooling) 3-way control valves, branch airline controlling the valves. EPT controlling our branch airline.

 

[imok2]

If you don't have a preheat coil and the supply air EP is energized whenever the fan runs and the OSA dampers open,then it's just a matter of installing the freeze stat between the heating coil and the filters so that it shuts down the fan and deenergizes the EP. This should put the NO heating valve on full heat and close the chilled water valve.