cross-posted from: https://lemmy.world/post/34021020
I recently installed an Emporia Vue with monitoring for the individual circuit my water heater is on. It captured the very significant difference in energy usage from replacing resistive heat with heat pump.
Oh boy. So the heat pump is probably one of the most important inventions without which modern society wouldnt exist. It uses a refrigerant that has a low boiling point. It is liquified through the pressure of a pump on one side, and let to evaporate on the other side.
Because of the evaporation it can draw heat from there and then give it off at the other side. This way it can cool the cold side more and warm up the warm side more, subsequently “pumping” the heat from one to the other side.
Your fridge uses a heat pump. Most AC units use heat pumps. Any industrial room cooling like warehouses, trucks etc. involves heat pumps.
Now comes the neat thing. For heating a heat pump can have an efficiency factor up to around 4. So 1kW of electrical power can give you up to 4kW of heating power. This is because the electricity isn’t transformed to thermic energy, but rather used to move thermic energy from the outside inside.
Heat pumps are amazing, especially as modern ones provide both AC and heating efficiently. Only caveat is that the efficiency is dependent on the temperature difference it needs to surpass. Because of that older radiator installations that were designed for a higher temperature might need replacement with newer larger radiators. Also if it gets really really cold you might need a classical heater to support the system.
Not to be ungrateful for the explanation, but I’ve had heat pump HVAC for years. I’m originally from Oklahoma and everyone has a heat pump. In fact, I find it weird that they’re controversial in any way!
I meant I had never heard of a heat pump water heater. Which sucks because I just had a new unit installed last year. :(
Are they extra expensive? More complex install?
Heat pumps have less immediate heat and less maximum heat. As electricity conservation becomes increasing vital heating appliances utilizing heat pumps are increasingly becoming an option but those limitations remain.
For water heaters you just need to be certain it replenishes quickly enough for your needs. But for other applications like dryers you may find yourself frustrated with the actual downsides regardless of choice.
A lot of hate for heat pumps comes down to people using them like resistive or gas heating rather than like the backwards air conditioner they are.
Like with an AC you need a place for the outside unit and do some piping. They are also more expensive, but the costs usually amortize well before a new unit is needed. They don’t heat as hot, so you might need a bigger tank.
First, from all the ones I’ve installed, they have all been all in one units with the heat pump on top of the tank that use the room air as the source. Not saying split hp water heaters don’t exist, I just haven’t seen any. The install for these units is practically identical to a standard electric water heater except you need to pipe a drain for the condensate.
The ones I’ve seen also include a resistive element and can act in a hybrid mode where they heat the water mostly with the heat pump, but can use resistive to boost the temp.