1. The central heating circuit is controlled by a 2-port Danfoss valve. I replaced the motor head a couple of years ago. I've taken it off and got the heating going by turning the valve on manually. But I don't think this motor is faulty - but i've forgotten how you fit it back on. How is it done - what positions do the valve and motor need to be set to.
2. The hot water motorised valve is buzzing loudly (I thought it was the Danfoss, but no). This is a 2-port Honeywell HF 002 body and is now about 15 years old - is this one OK to take off and replace or is it integral to the pipework (getting conflicting info about this).