Howdy folks! New homeowner here from Long Island NY! The boiler, water heater, and AC in my place are all 20 years old so I know they're 1) not energy efficient and 2) approaching their useful life-span. I'm trying to plan out their replacement/upgrade.
Some details: 2,800 sq.ft. 2-story house w/ basement. Currently has: 5-ton SEER 13 AC unit and single-speed AHU w/ single-zone ductwork in unconditioned attic, approx. 80% AFUE gas-fired boiler for 2-zone hot water baseboard heat (1 zone per floor), and a 50 gallon gas-fired HWH of unknown efficiency. The house also has 7.5KW solar panel system.
So... going to make my attic semi-conditioned to protect a new variable-speed AHU and ductwork, and install an air-source heat pump (since I generate a lot of electricity) to handle HVAC for three of the four seasons (basically anytime the outside temp is above 32). Undecided about whether to get two units (one for each floor) or try 2-zone ductwork, or just replace in kind (single-zone, whole house). Feedback welcome!
I'm trying to decide on the boiler/water heater with Winter in mind. My thought is to install a non-condensing boiler and a heat-pump hot water heater with an optional hot water exchanger. Spring, Summer, and Fall - the boiler is off and the HWH runs in heat-pump mode on solar power (bonus cooling and dehumidification). Winter - boiler is on and the HWH works in "indirect" mode. Since I have hot water baseboards throughout (designed for 180F supply) and will be adding an indirect water heater, I'm 99% sure a condensing boiler would not help me because I feel the return will very likely be above 135F.
What supply temp is typically needed for an indirectly-fired water heater?
Is a condensing boiler still more energy efficient than a non-condensing one, even when it's not in condensing mode?
Thanks all!
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