My in-tank heat exchanger is finally installed. I replumbed my main heat loop to allow for the HX loop, Rennai Tankless bypass, and larger pipe to reduce friction. The HX is installed in the top rear ofthe upper tank. Fired up the boiler last night and we are now 100% heating with wood (unless I want to enable the LP heater). I still have to wire in the Taco EBV for automatic control of the Rennai bypass but that will be easy enough and then insulate the tanks. I opted NOT to use the Taco "00-VS" series setpoint temperature pump and control because of cost (over $600) and schedule (4 week lead time). I opted instead for a $90 tempering valve and I can add a circulator later if I need to (but I don't seem to need it yet). I'll miss my 1000 gallor radiator in the basement (not really). In the pictures, the white/creame pipe in this domestic cold water supply in CPVC; the red and blue PEX is the domestic hot & Cold distribution in the house (home run for each fixture); the copper is the heating loop. Under floor is 7/8" PEX. Thank you to everyone who gave me installation and operation advice.