Having had the system inspected, it’s been decided that we need a larger GSHP for the system.
So we’re not (yet) on green heat.
A larger heat pump is on order and we’ve been switched back to the gas boiler in the meantime.
There’s an outside chance of the exchanger arriving and being installed tomorrow but next week looking the likelier.
The good news is that the water is coming out at good volume and at a high temperature of 12.1c.