Planned Obsolescence is your fault

[Maximilian Hohmann]

(01-03-2019 02:02 PM)Thomas Okken Wrote:  The EER ratings I'm googling suggest a usage of about a quarter of a joule, or less, of energy used per joule of heat removed by modern AC units. That strikes me as plausible since it's also in line with heat pump efficiency ratings I'm seeing.

There can be no fixed numbers as it very much depends on the process temperatures. My figures above were for the worst case. Unfortunately this is what I see very often: Protable AC units with a hot-air hose that is supposed to be routed through a hole in the window (or wall), but which are operated with the window half open so that the hose can hang outside. Used like this, they have a negative efficiency because they add the heat from their electrical motor to the room temperature and really only cool their immediate surroundings. But even when operated properly these things are very inefficient.

For the studio of my wife (which is above the garage in a separate building) we use an electrically driven heat pump with an air-to-air heat exchanger. Under optimum conditions (say outside temperature 15°C for a room temperature of 20 degrees) it will add about 2.5kW to the 2kW that the motor draws, thereby more than doubling the electrical energy. Today (-5°C outside) it will "harvest" less than 0.5kW with those 2kW input. And operated the other way round (for cooling) the figures can only be worse because other than with heating the heat lost by cooling the engine is really lost.
(Heat pumps that can use ground water or geothermal energy the efficiency is much better.)

Regards
Max