So a friend of mine who is a conventional HVAC contractor is trying to talk me out of a desuperheater as part of my geothermal heat pump, which will run a system largely of hydronic radiant heating and cooling ceiling panels from Messana.  I have already purchased and was planning to install a Rheem Marathon water heater and a second one for the desuperheater tank. He says that when systems were still running R-22, desuperheaters were efficient and cost effective, but that given newer refrigerants, like R454b, they aren’t anymore. I may have an option to purchase and install a new geo unit with R410a, or wait for the production line to upgrade to R454b and get a new geo unit with the desuperheater. What should I do?  There is no downside to waiting – no time crunch.