Locating 3 way CH valve

[Jon89]

Hiya. We recently moved into our home and have a problem with the central heating and hot water system. The boiler is a glow worm and is about 10-15 years old at a guess. The hot water works but when the boiler is on for the water the heating comes on as well. A Gas engineer has said that the fault will be the 3 way valve but we can't locate it. The previous owners had the hot water tank moved into the loft but the plumber who did it says that the valve was not by the old tank. Does anyone know the best way to find it please? Thanks in advance

 

[SimonG]

Close to where the old airing cupboard is?

 

[Jon89]

Hiya Simon. The old tank was in the bathroom but that was refurbed by the previous owners a couple of years ago and moved to the loft. The plumber who moved the tank says the valve wasn't there as he would have moved it at the same time. We really don't want to be ripping the house apart to find it if at all possible.

 

[SJB060685]

Trace the pipework from boiler to old cylinder cupboard.
Is this a new problem or one you have inherited?
Its possible and only a suggestion you have reverse circulation.

 

[Jon89]

Hiya. The main problem with tracing the pipe work is that it will mean potentially causing lots of damage in the process that we want to avoid if at all possible. We have inherited the problem. Things are never simple!

 

[SimonG]

Probably doesn't exist then. Could be gravity hot water and pumped central heating.

Any pics of the boiler and hot water tank?

 

[Aquarius]

What about tracing wires from the cylinder?

 

[Jon89]

I'll give that a whirl next weekend when I have time to get in the loft. Thanks for the advice

 

[SimonG]

What about tracing wires from the cylinder?

I was hoping the pics might give us a few more clues

 

[Chuck]

Check the paperwork for the boiler. If the 3-way valve was installed somewhere non-obvious a decent installer will have left a note, usually in the back of the instruction manual.

You can get simple endoscopes on Amazon for around £50. One of these may help minimize the damage if you have to go looking...

 

[SJB060685]

Ok. Let's rule out pumped CH and gravity HW. Is there a cylinder thermostat on the cylinder? If there is then there is a valve somewhere.

 

[Jon89]

I'll get in the loft at the weekend and post some photos. Thanks for all the help

 

[Jon89]

I'll get in the loft at the weekend and post some photos. Thanks for all the help

Finally got in the loft and took these photos. Not sure if they will help!

 

[SJB060685]

Thats an unvented cylinder, which shouldn't be on a three port unless there was a two port on flow to coil as well I cant see either. I can see the cylinder thermostat wired in which all of the above means there are valves somewhere.

 

[Jon89]

Thats an unvented cylinder, which shouldn't be on a three port unless there was a two port on flow to coil as well I cant see either. I can see the cylinder thermostat wired in which all of the above means there are valves somewhere.

Thought as much. The problem is trying to find them!

 

[SJB060685]

Thought as much. The problem is trying to find them!

I appreciate that. That white cable coming out of cylinder thermostat will go to some sort of wiring centre. If you can locate that then trace the other cables going into the same wiring centre. If the valves are close to it then it will be black cables you're looking for in the wiring centre, however if the valves are at a distance then the cables could have been extended and are terminating in the wiring centre in white cable.

 

[Jon89]

I appreciate that. That white cable coming out of cylinder thermostat will go to some sort of wiring centre. If you can locate that then trace the other cables going into the same wiring centre. If the valves are close to it then it will be black cables you're looking for in the wiring centre, however if the valves are at a distance then the cables could have been extended and are terminating in the wiring centre in white cable.

Thanks for the help. I'll try and trace them back and see where they lead. The old tank was in the bathroom but the guy who move it into the loft is adamant that there was no 3 way valve near it

 

[Ben-gee]

He’s stitched you up putting the combination valve so low down too, much better if it’s above the cylinder.

 

[SJB060685]

He’s stitched you up putting the combination valve so low down too, much better if it’s above the cylinder.

Not just better but as is theres no way of telling if the expansion relief valve is dripping. It should always terminate into D1 of the tundish. I had noticed that but the OP is trying to find another fault at the moment and I didn't want to over complicate things.

 

[Jon89]

Not just better but as is theres no way of telling if the expansion relief valve is dripping. It should always terminate into D1 of the tundish. I had noticed that but the OP is trying to find another fault at the moment and I didn't want to over complicate things.

That's far beyond my abilities and understanding so will probably need get the professionals in at some point. Thanks for all the advice

 

[Ben-gee]

To be fair I think I can see the tundish so that’s ok. It’s just that now the cylinder needs to be drained to work on the combination valve.