On 25/05/2020 21:29, John Smith wrote:
On 2020-05-01 23:21:24 +0000, Davey said:

Was this ever resolved?

Well I've finally got around to getting under the stairs to investigate.

One thing for certain - the motorised valve controlling the hot water
was jammed half open, and the valve body has a very small leak but it
seems to have destroyed the motor body, which is a shame as I only
replaced both actuator heads recently (the other for the heating circuit).

So I need to replace the valve body but that's beyond me although I do
have the part as I bought it with the motor actuator. But It looks like
I need a new actuator...

i presume the system needs a drain down to do the valve but it's just a
couple of large screw nuts.

Yup in principle - although it does depend where in the system the valve
is, as to how much of a drain it will need (valves in a loft for example
can often be change with only a partial drain down).

2 port valves are easier to swap than three port - especially if the
valve is a close match and can re-use the existing back nuts and olives.
In principle, undo both nuts, swap valve and re-tighten. The devil is in
the detail, like how easy they are to get at, and how rigid the pipes
are (i.e. will they move enough to let you get the valve out).

At the same time I guess I should get the expansion vessel serviced. I
think the boiler is fine - it's a bullet proof Valliant that was
serviced a year ago.

You can check the pressure easy enough yourself. Not sure about the
Turbomax, but on the Ecotecs the expansion is readily accessible and the
shrader valve is right on the front right:

http://wiki.diyfaq.org.uk/index.php/...rIntakeOff.jpg

(expansion vessel is the silver thing on the right)

I've freed the valve spindle and applied a bit of lubrication for now
and will operate it manually til I find someone who can replace it and
the motor head - unless anyone thinks I can do it?

Its certainly DIYable... Turn boiler off, drain down, swap valve,
reconnect to wiring. Refill[1], and bleed, and set system pressure, and
turn boiler back on. If all looks good. The turn off again, and add some
fresh corrosion inhibitor. Turn back on.

However it depends on your level of confidence and having at least some
basic tools like spanners to fit the nuts etc.

[1] Vaillant boilers often have a handy test program you can get them to
run at startup, that will just run the pump and show you the system
pressure without trying to fire. Ideal for refilling and purging the air
from the system.


--
Cheers,

John.

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