The physics of “Air Sourced” heat pumps seems nonsensical to me, the basic idea is to draw heat from the air outside and use that heat to heat water.
The principle is similar to that of an inverted refrigerator where we use a compressor and refrigerant to extract the heat from an insulated sealed box (the fridge) and dissipate the heat through the condenser coils often on the back.
The problem with air sourced heat pumps is that in the winter when we need more heat and thus maximum efficiency the outside air is generally cold meaning the unit is trying to pull heat from cold air, so straight away we have a large inefficiency when we least need it, the negligible heat extracted (during cold periods) then has further losses during its conversion from liquid to gas as the heat is transferred.
In many cases when it is too cold for the heat pump to extract enough heat from the ambient air the units rely on basic electric immersion heaters to heat the water, hence the increase in electricity usage during cold weather.
In my opinion these units are greatly overcomplicating the way we heat our homes for little tangible benefit.
David, I would like to hear a presentation of your take on Fossil Fuel - are oil, gas and coal really FF? Thanks.
Hi Harry. Will do one. And they’re not ff
The physics of “Air Sourced” heat pumps seems nonsensical to me, the basic idea is to draw heat from the air outside and use that heat to heat water.
The principle is similar to that of an inverted refrigerator where we use a compressor and refrigerant to extract the heat from an insulated sealed box (the fridge) and dissipate the heat through the condenser coils often on the back.
The problem with air sourced heat pumps is that in the winter when we need more heat and thus maximum efficiency the outside air is generally cold meaning the unit is trying to pull heat from cold air, so straight away we have a large inefficiency when we least need it, the negligible heat extracted (during cold periods) then has further losses during its conversion from liquid to gas as the heat is transferred.
In many cases when it is too cold for the heat pump to extract enough heat from the ambient air the units rely on basic electric immersion heaters to heat the water, hence the increase in electricity usage during cold weather.
In my opinion these units are greatly overcomplicating the way we heat our homes for little tangible benefit.
Thanks Rob, excellent contribution!