I've been toying around with my water-to-air HX in the past three or four days and have made some interesting discoveries. I'm wondering what the boiler room thinks is the best way to run your setup. Currently I run a single water-to-air HX in a forced air NG furnace. I also have 1000 gallons of storage. I've been playing with the flow on my HX loop to see where I get the best heat to the house vs. how much temp drop I get. When I run the HX loop wide open I get about 20 degrees temp drop through the loop. Say 170 to 150. If I throttle the flow on the loop I can run the temperature drop all the way to up 60 degrees or so. The highest has been a change from 170 to just over 100. That's the extreme. I know 20 degrees is the typically the target. But what about the effects on tank stratification? When I run my HX loop at the 60 degree temp drop setting I get almost no mixing in my tanks. I can run the bottom of the tank all the way down 100 degrees and still have 160+ on the top. When the HX loop is wide open I get a lot of mixing and typically can't maintain anything more than a 20-30 degree difference between tank top and bottom. Anyone see any benefits to running either way? I'm running wide open right now because my pump does not like being throttled down. If I were to make it permanant I'd have to bust for an adjustable speed or smaller pump. Any thoughts are welcome!