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Primary circuit or free-flowing volume, heat pump

Posted: Tue Nov 23, 2021 6:53 pm
by LouiseSJPP
I have had an air-source heat pump system installed. It interfaces to the existing central-heating system, replacing a boiler. At the interface, the installers placed a 12 litre low-loss header, creating primary and secondary pumped circuits.
The heat pump spec calls for '80 litres of free-flowing volume.' I'm assuming that means the primary circuit volume. In this case, the primary circuit is 4 litres of pipework, 12 litres of loss-loss header and a 26 litre buffer in the Indoor Module. This doesn't add up to 80...
Am I understanding this right? Will this system be short-cycling?