Why might circulation pumps keep consuming electricity after a heat pump stops?

The short answer

A circulation pump can remain required for an approved post-run period even when the compressor has stopped. Residual heat, water-temperature equalization or another equipment function may explain that state. Its exact purpose and duration come from the installed system documents. Compressor-off time is therefore not automatically zero system load or permission to remove pump power.

Find the documented post-run function

Ask the heating supplier which pump continues, what controls it and which flow path remains open. Distinguish the heat-pump internal circulator from distribution pumps or unrelated building loops. A recorded motor current alone does not identify why the pump is running. Do not apply another manufacturer's overrun duration as a universal operating requirement.

Represent it as a separate load state

Hypothetically, an excluded 0.15 kW pump running twenty minutes after an event uses 0.05 kWh. Ten such events would use 0.5 kWh at the same simplified boundary. These invented figures show why event count matters. If a whole-system meter already includes the pump, do not add that energy again. Keep the compressor and circulation timelines separate when explaining the meter.

Record an event's final pump stop separately from its compressor stop. Using only the latter as the end of the system operating interval can omit several genuine auxiliary periods over a day.

Respect the complete service sequence

Ask whether a proposed wind-related stop request permits the system to complete its normal post-run using the available supply. A demand-control signal and cutting electrical power are different actions; only the supported interface should be considered. Evaluate whether more frequent permitted cycles increase auxiliary consumption even if compressor energy appears unchanged. Provide the pump identity, post-run behavior and metering boundary in the wind enquiry. The integrator must demonstrate the proposed electrical contribution without assuming that MARSTON equipment can interrupt or manage the heat pump's circulation controls.