The current model equivalent for what you have is the Danfoss PL35G. Made for R-12 or R-134A, 2.0 cc displacement. Heat transfer at 0 degC is about 100 watts or so. COP about 1.5 at that evap temp. Much too small for heating 1000 gallons of water. Not too bad for a mini-fridge or water cooler.
I quickly found a white paper in Russian:
http://www.schiessl.com.ua/docs/danf...pressors/3.pdf