Obtain the installed heater configuration

Confirm the actual heater and supply arrangement, rather than assuming every product variant has the same stages. Ask which modes permit concurrent compressor and resistance operation, and which interlocks or capacity limits the manufacturer supports. Identify separate water-heater boosters where fitted. Do not combine all possible stages into one simultaneous case unless that case can occur in the accepted configuration.

Calculate one supported combination

Hypothetically, a compressor drawing 3 kW and an allowed 4 kW resistance stage produce 7 kW combined input before excluded auxiliaries. An additional stage that is not permitted simultaneously should not be added to that case. These invented values illustrate state-based summation, not an equipment rating. Voltage, current, phase demand and duration also belong in the electrical assessment.

Tag heater stages in measured records if supported. Otherwise a sudden higher input may be wrongly attributed to compressor inefficiency when it actually belongs to an accepted resistance-heating state.

Retain service during the demanding weather case

Ask the heating owner whether backup is needed during low temperature, defrost, faults or another identified condition. Compare those states with supported wind chronology, without assuming colder weather guarantees usable generation. Any proposed restriction on backup must be approved against the required heating service. Provide the accepted combinations and their control authority in the wind enquiry. Manufacturer backup-heater examples do not establish that MARSTON equipment can shed a stage, supply the whole peak or replace the heating designer's required alternative source.