The only thing i would add is a way to easy flush the HX i have a large plate HX on my system that transfers the wood boiler heat to preheat my NG boiler water. I wish i would have put 4 unions or 2 three way valves just so i could flush it out once in a while to make sure i was getting the best Delta T across it. But heaterman might have already added something to do this that i am not seeing.