WOW! Congratulations. Lotsabucks. This is not a condensing boiler, is it? Now, like Sgt. Shultz, I know nothing, but I have a question about summer water heating. Isn't is very expensive to heat the boiler in the summer for the water heater or is the new system with the tank a more efficient method than having the instantaneous coil? In the summer when you are just heating water, can the boiler run at a lower temperature? Would a heat pump water heater with an electric element for back up cost less to run? Will those pipes get foam insulation sleeves after the inspector's approval?
I have a very simple hydronic system in the glass room addition to my house. The closed system is a 30 gallon direct vent gas water heater underneath in the shop/plant room feeding baseboards above. The water heater fires on its own thermostat. The room thermostat will open the valve and start the circulator pump, but it also convects on gravity with the valve manually locked open so it is the one system I have that is not dependent on electricity should the worst happen. The ceiling fan keeps the air well mixed so the floor is not cold. Keeping that room warm allows me to delay using the forced air gas furnace at the start of the heating season and takes a great load off the furnace when both are in operation.
Toggle, have you ever discussed steam heating with Jon of Melrose and Chatham, MA? He converted from hot water to steam in his Melrose residence.