"xtinexoop" wrote in message
om...
Hi

We have a problem with the central heating. I think we have narrowed
it down to the motorised valve which is a Myson 3-Port valve.

The problem is that although we have hot water the heating doesn't
come on unless you use the manual override lever. We can see from the
lights on the actuator that the timer control is passing the right
'signals' to it, but it isn't opening the valve.

I had a look on the Myson website and it is possible to buy the
'actuator' bit seperately and its 4 screws and some simple wiring to
replace which having taken the current one off to have a look I think
I could manage. The alternative would be to buy a complete new valve
but I understand that would require draining the system and would be
beyond my capabilities and expensive to have done (a quote to replace
it with a Honeywell valve is £150+VAT).

Can anyone tell me whether it would be false econonmy simply to
replace the actuator - is it like replacing the disks in a car and not
getting new pads at the same time for example?

Any suggestions gratefully accepted.

Thanks


Christine

As others have said, as long as the spindle of the valve rotates freely, and
as long as there are no obvious leaks from the valve, it is perfectly
reasonable to replace just the actuator. The simplest thing is to replace
the whole actuator assembly - but make a careful note of where each of the
(probably 4) wires connects before disconnecting the old one.

If you're slightly more ambitious, you may get away with just replacing
whichever of the internal components of the actuator are shot. It contains a
motor, a resistor, a diode (I think) and a couple of change-over
micro-switches. It can be done, but it's a bit fiddly - and requires
reasonable soldering skills.

Roger