Can Any one tell me what this is on this HVAC sys?

Can Any one tell me what this is? It is an old 1955 home with an updated HVAC sys. It appears to be some sort of circular pump heater or something? Not sure, that’s my guess. Any help is much appreciated. Thank you.

Looks like a Heat Recovery Unit.
They work, until the next tech comes along and disconnects the tubing from the newly installed components (water heater or A/C unit).


Thanks Dominic. Hum… so does it some how take the place of or aid a heat pump? There were two valves, one for each line, outside the box.

Look them up, lots of diagrams and such online, HRU’s take the waste heat from the condensing unit and transfer it to the water heater. “Free” hot water, more or less…