have bought a central heating protection cover from Southern Electric recently and their engineer came yesterday to have an initial inspection. I mentioned to him that in the summer when I turn off the heating but leave the hot water on, the heating is still on. He said this is because the mid position 3 port valve is faulty. Before the valve is changed they cannot cover us. And he said the whole job would probably cost around £200. He was not able to give a fixed price as it depends on the time it takes to drain the system and fit the new valve.

I wonder whether I should have the valve changed, or just leave it for now cos it is only a minor inconvenince in the summer (I just turned the hot water on for an hour anyway).

Any suggestions? Thanks in advance.

This is not a major problem, do you know where the mid position valve is, if so follow the cable to what should be a rectanguar junction box. Make sure you isolate the electricity, Cut the wires from the valve leaving enough on the block so you can disconnect and reconect the new wires one at a time. Once done simply unscrew the old valve and replace with the other. All for less than £50

The actual problem is proably the sych motor a lot cheaper than byeing the hole head, its inside the head of the valve and is held on by 1 or 2 screws again wire for wire but more difficult.

There's a clear moral there - ie dont be too chatty with the engineer when they're inspecting a setup for adoption!

Then in the summer when SHOCK HORROR you found the heating was heating as well as the hot water, you could have called them out then :)

I had that same problem a couple of times , fortunately when covered by BG years back - it was just the first radiator (in the bathroom that got hot as valve either wasn't closing fully, or water tank was getting warm quickly enough for the whole radiator system not to heat up).

As heating/sparking has said...

You'll have a 3 port valve by one maker or another, ie like these:
http://www.screwfix.com/prods/93941/Plu ... ised-Valve
http://www.screwfix.com/prods/81844/Plu ... Valve-22mm
(Reading the Adobe PDF manuals scanned by Screwfix is quite enlightening!)

and most of them will have a really small electric motor inside them like this one
http://www.screwfix.com/prods/28670/Plu ... nous-Motor

In fact I believe based on those manuals that there are 3 'depths' of fix/replacement ???
1 the valve body with actuator (ie "box", with its electric cabling ) [need to be clear whether a 'mid position' one is required or not ?]
2 just the actuator box attached to the valve
3 just the actuator motor inside the actuator box

Think heating/sparking has left out some of the possible complexity of draining etc etc though - more like a £100 job than £200 though ?

yes, certainly the complexity of draining & refilling!

there is no need to drain when changing the zone valve head

I'd be thinking the problem is in the water section, not just the head.

The fact is passes would indicate to me that the valve seating is faulty.

Also not all (old) 3 port valves are able to have just the heads changed!