The U.S. Department of Energy on Friday proposed energy efficiency standards on water heaters it said would save consumers $11.4 billion on energy and water bills annually.
The standards on residential water heater efficiency, which are required by Congress, have not been updated in 13 years. Water heating is responsible for roughly 13% of both annual residential energy use and consumer utility costs, the DOE said.
I do like how the article goes out of its way to mention that Joe Biden is a Democrat and Donald Trump is a Republican, just in case we didn’t know.
Anyhow, it does specifically mention reverse cycle electric water heaters, which I clicked on this imagining were the only path forward if anyone wishes to increase the efficiency of an electric storage tank water heater. Existing electric storage water heaters are actually already remarkably close to being perfectly efficient, since very nearly all of the energy consumed goes into raising the temperature of the water and provided you don’t let the thing sit idle for days on end, that heat energy stays in there pretty damn well, also. Even a bog standard electric water heater with resistive heating elements has around 90% energy efficiency.
Then I remember how many people in the US have natural gas powered water heaters, because they’re “cheaper,” which are at best something like 60% energy efficient.
Because “efficiency” here ill defined, 100% is not the most efficient a heater can be. Heat pumps move more heat than is needed to power them, are much more efficient than electric heaters, and have “efficiencies” well over 100%. Good ones have 400% “efficiency”, in that 1 J consumed will put that 1 J into the the substance and move another 3 J from the environment (thus cooling the environment) into the substance.
If you use a heat pump water heater, it will help cool your house. In areas that cool in the summer, it’s essentially free hot water. In the winter overall energy consumption to offset the cooling breaks even compared to an electric water heater.
Similarly, air source heat pumps are much more efficient than gas or electric furnaces for heating a building. They’re comparable to a typical AC unit for cooling, as an AC unit is just a heat pump.
In many regions, ground source heat pumps are even more efficient for both heating and cooling, because the ground temperature is nearly constant and at a convenient temperature, so it serves as a huge source and sink of energy.
Correct. It seems bonkers at first glance that anything could have an efficiency over 100%, but in the case of heat pumps specifically for the use case of heating something (water, your house, etc.) the above is true, and you can achieve over 100% in that context.
One complaint I can predict about heat pump/reverse cycle water heaters is that they are not silent, whereas a resistive element one is. (Gas ones aren’t silent either, though, so there’s that.)
I have a hpwh and , when the coils aren’t leaking coolant (repaired twice under warranty) it works well. I keep it in a room that has the washer/dryer, spare fridge, icemaker, and my espresso machine - all devices which would work against my A/C in the summer. It keeps that area nice and cool. In the winter I shut off the hp and run it in resistance mode or it really cools the basement excessively (which I’d also where my home office is).
The only other drawback is that the heat pump is very noisy compared to, say, a refrigerator or a good mini split heat pump - the little fans they use on the exchanger just whine.