Flow and return

Published by Brian Coyle on

design tips neatpump banner

Flow and return temperatures on a heat pump are crucial to increasing efficiency and reducing OPEX spend but what is the reason behind this?

Lower that flow temperature:

A lower flow temperature is the easiest way to increase the heat pump efficiency. This is because it takes less electrical input energy to reach the lower temperature. When looking at putting a heat pump into your project, gather the data and interrogate if you really need that high temperature?

Increase that Delta T:

A Heat pumps efficiency increases with a widening of the flow and return delta T on the heating side of the heat pump. This is due to part of the refrigeration cycle known as sub cooling – essentially allowing the heat pump to produce more kWs with no extra electrical input.

It’s the water off not the water on:

Boreholes get people excited as they could find water at 12°C and assume this makes the heat pump super-efficient but the borehole has a small flowrate so they operate on a large delta T and return the water at 2°C. This is the same as a river at 5°C returning at 2°C – why? The water off temperature sets the evaporating temperature not the water on.