Split-System Heat Pump Water Heater
jadziedzic
| Posted in Energy Efficiency and Durability on
I’d really like to use a split-system air source heat pump water heater in my new home, but I’m not sold on the suitability of the SANCO2 for use in climate zone 5 (I’m very concerned about the potential for freezing of the potable water circulated to the outside unit). Other than the Daikin Altherma are there other split-system brands to consider? A Google search doesn’t turn up a lot of options.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
I think a split system costs too much to be cost effective. I would go with a standard heat pump water heater. Even if you run the unit in resistance mode when cold for three months out of the year, it will still be cheaper in the long run than trying to make a split system work.
If you must have a split system, the way I would do it is with a glycol loop and an indirect tank. This would avoid any of the freezing issues in cold climate.
The best setup would be reverse indirect where the domestic hot water is run through the coil and the heat pump is connected to the tank. This would allow for better stratification of the tank which is very important for efficiency with a CO2 based heat pump. You could also use an unpressurised tank with a couple of copper coils which can be even DIY from off the shelf plastic tank.