DC inverter compressors
A fixed-speed compressor has two states: full power or off. A DC inverter compressor changes its speed, so the heat pump delivers what the building needs at that moment.
How it works
The inverter converts the mains supply to a variable-frequency drive for a brushless DC compressor motor. Changing the frequency changes the speed, and the speed sets how much refrigerant is pumped and therefore how much heat is moved. Every RV model uses a Mitsubishi DC inverter compressor.
Why it matters
- Fewer starts and stops. Each start wastes energy and wears the compressor. Modulating down avoids most of them.
- Better part-load efficiency. A heating system spends most of the season well below its design load. At reduced speed the heat exchangers are relatively larger for the heat being moved, which helps efficiency.
- Stable water temperature. Output follows demand smoothly instead of overshooting and falling back.
Reading the capacity range
Each RV product page lists a heating capacity range (for example "4 – 13.8 kW") and a rated capacity at A7/W35. The range shows how far the compressor can modulate; the rated figure is the output at one standard test condition. Neither replaces the capacity at your own design outdoor and water temperatures, which is what sizing must use.
Minimum output and system volume
Even an inverter has a minimum speed. When the building needs less than that, the unit still cycles, which is one reason each model specifies a minimum system water volume.
Related: Cold-climate operation · Compare RV models
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