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.
Provided that the valve is moves freely just changing the motor should do
the trick. make a sketch of which wire goes where and then take the old
motor with you when you buy the replacement just in cas eit is a bit
different or there is a choice of motors.
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.
You can buy the individual parts which sit inside the valve head at a
fraction of the cost of buying the whole thing, and they are very easily
Test the microswitches to see if they are passing the voltage signal along
to the other parts of the system.
example of a microswitches here: http://tinyurl.com/opo0
Make sure that the synchron motor is running when you make a call for
heating (switch the system on) and is opening the valve.
example of synchron motor here: http://tinyurl.com/opoc
The parts used inside these valve heads are pretty universal, mainly because
they all come from the same manufacturers, and they only cost pennies
compared to buying the whole head part. Try looking around your local
repair shops for them and save yourself a good few pounds.
Thanks for taking the time to reply
I am going to go and check that the spindle bit is spinning freely and
if it is then I will replace the actuator.
Although I like the idea of only replacing the bits I wouldn't know
where to start...
The actuator is about £45 + VAT which is a still a lot cheaper than
getting the whole thing replaced, as I can do the wiring myself. I
will get the same make to save worrying about the 'fit'.
Anyone recommend a good online source for the actuator? Its an ACT322.
http://www.hav.co.uk/products/potterton_myson.htm 41.34 + vat, you need to swipe
whole page with the mouse to see the prices, they're black on black. or
http://www.onlineboilerspares.com/acatalog/BOILER_CONTROLS.html 45.00 + vat
but best of all:
do the whole valve for 42.50 (if it's the 22mm one, pls chk) so you could buy
the whole thing
& swap the head or replace the valve if needs be. If the latter, tell the
supplying the parts :-)
On 26 Sep 2003 03:22:23 -0700, firstname.lastname@example.org (xtinexoop) wrote:
I've been buying bits from MJT Controls. This looks like the page you need:
Appears to be £31.03+VAT+delivery, which I think is a mere £2.50
I found them very helpful on the phone (went and got a fan off the shelf to
confirm whether or not a gasket was included) and delivery was very fast
That's a shame. Synchron motors are about a tenner! Most manufacturer's
parts are interchangeable. Don't know specifically about Myson.
You can get a whole valve for 35 quid, so don't pay 45 for just the head.
Thanks for all the help guys!
I have bookmarked the supplier pages.
The tenant we have in the house has now told us its all working again!
(maybe it was just 'stuck' after being off over the summer?)
I guess its gonna go at some point though so I might get the part now
and hold it 'in stock' ready for when we need to get it done!
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