"Christian McArdle" wrote in message et...
the cables from the switch go to the pump and the zone valve.

OK. I have no idea what the switch does, then. If it has worked before, I'm
not too worried. If it hasn't, then it could be some harebrained scheme to
simply heat one tank of water at a time.

what will happen when I move the switch to "Manual"? do I need to replace
the zone valve with the same model number?

This will open the central heating and hot water circuits permanently, so if
the boiler fires both will go on. Your hot water will probably get hotter
than usual as the thermostat won't close off the circuit. Any rooms without
TRVs will also get hotter. However, you do get heat and water.

do I need to replace the zone valve with the same model number?

You don't normally need the whole valve, just the actuator head. In fact,
most manufacturer's actuators are compatible with each other. However, you
have to choose the correct type. To find out if you only need the actuator,
remove the plastic box and ensure the valve itself operates without undue
force. You might also get some idea by how easily the override lever moves.

There are three main types of valve:

a) 2 port (i.e. on/off)
b) 3 port diverter (i.e. A or B)
c) 3 port mid position (i.e. A, B, or both)

You need to determine the correct type, although sometimes, (a) and (b)
above share the same actuator.

Christian.

I have opened the box and there is a cylinder with the word synchron
on it, I guess this is the actuater. There are springs at the bottom
of the cylinder and some wires going into it which go to the switch
that I was explaining earlier.

if I turn the switch off the spring's move and it appears to close the
water to the tank off, when I put the switch on the spring's move and
it appears to turn the water onto the tank as I can hear the water
rush through the pipes.

I think this is why it must give me one tank of water, then it goes to
the off position and will not open up again.

Can I send you a picture so you can see what I mean?

How can I check the valve?