Optimizing flow rate for ideal COP

[Andre_K (André Kühne)]

@bringiton

Pump power is indeed the cube of the flow rate (Affinity Laws).

Thanks for confirming and putting the Affinity Laws on my radar.

@bringiton

It’s also worth considering pump location. My pumps are in the basement, outside my thermal envelope (as is the water cylinder, which is a far bigger mistake on my part from an energy efficiency perspective), so heat loss from the motors is probably about 25% - pump heating COP ~= 0.75 (based on my rudimentary understanding of motor efficiencies).

Technically the kinetic energy of the water also ends up as heat via friction, so 100% of the electricity put into the pump ends up as heat somewhere. Will it really contribute to heating the house? I’ve got no clue.

@bringiton

The question then is whether it’s worth doing anything about it.

Well it costs me nothing to lower the flow rate and the little money saved each year does add up, even if it’s just an extra case of beer worth.

Generally, this should just be part of the heat pump controls. Maybe another inspiration for @langestefan and Advanced Heat Pump Controls.