Replacing three port valve All aspects of plumbing questions and answers, help, tips and information

[mikegm]

Apart from replacing the synchronous motor, could anybody advise on whether or not when replacing the valve body itself, the system should be drained down first? (or at least the primary circuit)

[plumbbob]

You will need to drain down unless the expansion and feed from the header tank can be successfully capped and you can cope with a fair amount of water escaping from the pipe.

Unless you are prepared to get wet, then draining is needed.