Looks a bit like?:

http://www.sunvic.co.uk/3pmv.h tml

I could not find the exact model number of yours on the site, and hence
can't tell if yours is a mid position valve or just a diverter. The
current one seems to be mid position.

yeah kind of! i saw that as well - but mine must be an older model as i
do not have the red switch like the on on the web.

So i have to manually open it right?


how do i know that this is 2 or 3 port valve though?

Count the pipes! - From your description yours is a 3 port. It has one
pipe in and two out. (A 2 port valve is just like a motorised tap - it
can be on or off. The three port can not shut off the flow of water,
only change its path).

thanks ;-) i wasnt sure because i have never seen a 2 port valve - but
should have guessed mine is 3 port! thanks.


i haven't opened up the plastic case yet - because i was scared it
might cause damage or water might come out - should i worry about these
things?

No - they are in two parts. The brass bit at the bottom is the wet part.
It will usually have a small spindle that sticks out of it to control
the position of the tap elements inside it. The box sat on top contains
a motor and some control electronics. The motor turns the tap.

It is not uncommon for motors to fail, or for the taps to seize. You can
usually remove the motor completely and see if you can turn the tap
spindle manually (perhaps with a pair of pliers - it should not take
much force to turn). You may find that if it is seized, it may only be
temporarily - manually turning it may fix the problem.


ok - so lets say i take off the cover from the box on top of the brass
- i should be expecting:

a) somekind of know or wheel that indicates what the valve is set
b) these settings a CH, HW and CH/HW - correct? or is CH,HW and
auto?
c) i should be able to turn the know/wheel to CH only and test if i get
CH

and lets say i can take off the motor completely (you mean the box
sitting on the brass right?) and i turn it manually and place it back
on and start again - if i still have no CH, i call a plumber to
replace the valve right?

thanks for the explanation on the pipes into the cylinder as well"


kiichi
the 7 day immersion heater timer was indeed connected to the top of
cylinder - so i think i can say that this is for the backup only right?
and can have it set to "PERMANENTLY OFF" setting??


So there is no connection between the CH programmer and the time switch
like you thought the other day then?

kiichi - when you say CH programmer, you mean the "7 day immersion
heater timer" ?

And "time switch" as in the boiler programmer? sorry to ask a daft one
here...

i had a look last night and i can only see 1 cable coming from the7 day
immersion heater.


If so, good - that makes it simple. It looks like this is an ordinary
immersion heater which you can ignore unless your boiler dies of you
feel guilty about having such small electricity bills ;-)

thanks

the pipe coming out of the valve out of the "hot water" port is HOT
the pipe coming out of the valve out of the "central heating" port is
warm/cold as it gets to the floor

That kind of indicates to me that there is no hot water going towards
the radiators, right?


Yup, spot on.

ok - so the only thing that i can feel by touching the pipes that are
not hot (enough) is one of the pipe coming out of the valve towards
"central heating" - so must be the valve set to HW only?


Or does the pipes for CH not get that hot??

Nope, it should get as hot as the pipe going into the valve (or the one
going currently to the cylinder)


ok - well it isnt.

as i said i havent opened up the valve (the white plastic on the valve)
because i was too scared to do it myself and cause damage but i can
do it myself right without getting a plumber in?

Yup, you can do it yourself.

thanks - wish me luck

all power to the valve, boiler and everything else in the airing
cupboard is OFF before i do this.

Yup - it is usually all fed from the boiler. So if you turn that off at
the wall the rest will be off as well. Note that this does not apply to
the immersion heater which will typically be independent.

that makes sense as when i switch off the power socket that is powering
the boiler (the power socket that has text "fuse" displayed on), the
boiler,boiler programmer, pump, valve and cylinder stops BUT the 7 day
immersion heater stays on!! so the power to that must be independent as
you said.

thanks for all the info - will update tomorrow!
kiichi