For Condo Bob or Others

Condo inspection today. Hydronic heat pump systems (2 zone) located in exterior hall closets. Central domestic hot water system for the building. It appears that the return vents(3) terminate in the closet with the elctronic filter on the front of the very old 1975 air handler. Water is circulated through the air handler. The humidifier humidistat is located on the closet wall, which makes no sense. Is this return air design unusual? Is the water source actually part of the AC Chiller system?

Condo Bob has never seen that type.
Watching this thread myself.

All I get is standard boilers,HVAC,Condenser units,Roof Chillers,on 2 pipe and 4 pipe ambient systems,with a rare Kewannee steam boiler in place occasionally that has been converted to gas in the early seventies.
Heat Pumps would mystify me.

(Yes I know they are like reversable A/C units)


Just spoke with a local retired inspector who inspected condos in this same bldg. The water circulation is actually chilled water for the AC mode, as there is no condensed unit. I have seen just the opposite, with hot water circulated for the heat cycle. Always something new to learn!!
Oh, the return air set up is standard for this particular bldg.

This looks like a water cooled AC unit and it is not unusual to have humidistat in that location as its sensor is in return duct.

Makes sense.
Gotta love this job as you never stop learning.

You never get 100 percent comfortable

Quite common in high rises down here

Must be a regional thing.

Were those wire caps I saw hanging?

So the closet is the return plenum which makes the humidistat location acceptable. Interesting stuff!