pageflightReplaced my electric resistance water heater with heat pump, dramatic reduction in energy usage
Out of curiosity, is your new water heater inside your house in a heated area? If so is your house heated with electricity (heat pump or resistance) that would also be on this chart? Or do you have fur6nace burning NG or propane?
Not that heat pumps are bad, they are fantastic. But if your house heat isn’t also on your graph, you’re not seeing the whole picture. The water heat pump is actually using the very warm air in the house to heat the water. But it’s making your house colder and then your house heater needs to run more to make up the difference.
For areas where you want to cool or dehumidify the air these help though. So where I live, during the summer these would effectively be “free” - you were going to use that energy to cool the house anyway with your AC, now you’ve just put that heat in water instead.
You can also connect it through the wall so that it uses outside air for its energy. Modern heat pump technology is so good it can remain effective all the way down to -25C.
While that is true of heat pump technology in total, I have not seen any heat pump water heaters in the US that work below freezing. One example: my Rheem manual says it will work down to about 42F / 5C. Below that, it uses resistive heating elements.
But I’m sure it’s coming eventually to water heaters.
Yeah, I seem to be mistaken and you are right, -25 is accurate for heat pumps for room heating. But the Nibe F110 is a heat pump water heater that works down to -10C, and Indol have a few models that says down to -12C. Still quite good!