Naked Science Forum

General Science => General Science => Topic started by: bobobaggins on 01/07/2019 15:46:39

Title: How do vapour-compression and standard electric heating efficiencies compare?
Post by: bobobaggins on 01/07/2019 15:46:39
I have heard that all electric heaters have the same efficiency. If one were to run a vapor compression cycle in reverse to that of a air-conditioner, with the heat absorbing radiator outside and heat dissipating radiator inside as well as capturing the heat from the condenser and fan motor, could you get better efficiency then a standard electric heater?
Title: Re: How do vapour-compression and standard electric heating efficiencies compare?
Post by: Halc on 01/07/2019 16:22:19
I have heard that all electric heaters have the same efficiency. If one were to run a vapor compression cycle in reverse to that of a air-conditioner, with the heat absorbing radiator outside and heat dissipating radiator inside as well as capturing the heat from the condenser and fan motor, could you get better efficiency then a standard electric heater?
That's a heat pump, and yes, they're more efficient that a straight electric heater.
Title: Re: How do vapour-compression and standard electric heating efficiencies compare?
Post by: alancalverd on 01/07/2019 22:13:20
On a good day you can transfer around 3 times the electrical energy as heat. They work best with a small temperature differential so are generally used with underfloor heating running large volumes of water at 30 - 35 deg C rather than wall radiators at 50 degrees, but most domestic systems also include a hot water supply at 50 - 60 degrees. And of course if you have a reversible unit, you can use it to cool an area too.
Title: Re: How do vapour-compression and standard electric heating efficiencies compare?
Post by: chris on 06/07/2019 18:20:35
I think the stated performance for my aircon block / space heater (depending upon how you use it) is about 3kW heating rate for a 1kW electricity burn. Essentially you are pumping a lot more heat than the electrical energy consumption, hence @Halc pointing out that it's much more efficient than just plugging in an electric fire.