Heat pump water heater for supplemental hydronic heating
I am in the process of designing a high performance home and am working on the HVAC system specs.
I am in mixed humid (zone 3 – Greenville, SC).
Duke Energy offers some reduced rates for Energy Star certified homes (I am waiting for Piedmont Natural Gas to get back with me on their rates). These rates are 5-6% below standard rates.
I am considering a heat pump system with gas backup, but Duke offers a further reduction if the home is all electric (HVAC and water heating) which is nearly 20% lower than their standard rate with Energy Star and I am not sure if they will allow the gas supplemental heat option (I have emailed them this). Also, I am not sure the gas company will be offering a whole lot if I am only using them for supplemental heat, plus they charge you $10 a month whether you use gas or not.
So, in order to get the all electric rate, I was considering using an heat pump water heater to supply the supplemental heat (hydronic coil in the AHU). A recirculating pump would move the hot water to the coil from the water heater only when supplemental heat was required.
Of course, the drawback of this is the water heater is pulling the heat from the conditioned space and cooling the are. But, since this will only happen when supplemental heat was required that may be acceptable. AHU and water heater are in a conditioned basement.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part