The low power test was a success, so a larger dummy load was obtained- 3x 240V, 3kW water heaters connected in series.
The PFC was placed on a special tea tray test fixture and temporarily wired into the electric cooker supply in the kitchen.
According to my smart meter the result was 8.1kW input, though the other house appliances were using a few hundred watts at this point. The line current waveform looked nice. I used an EMI filter this time so the garbage at the switching frequency is reduced.