I need a new 38kW condensing boiler with weather compensation) and have
singled out the Keston C40. (The Keston C25 is too small and doesn't
have weather compensation.)

Does anyone have any comments, good or bad, on the Keston C40?

Keston recommend using this boiler with a Honeywell "Chronotherm"
controller with Open Therm comms protocol. Again, i wondered if anyone
had any experience to share regarding the Chronotherm.

Lastly, Keston distribute a 300L Spa cylinder to go with the boiler.
Does anyone know who is the original manufacturer of the Spa?

Thanks, folks