Mysterious pipework to ballcocks

[CouchPlato]

After living in my house for 20 years I thought it might be a good idea to have a closer look at the pipework in the central heating system. Yes I know
I’ve got an old school system with two tanks in the loft. Most of the pipework makes sense to me, apart from the supply of mains water to the two ballcocks, one in each tank.

So there are two pipes coming up from the ground floor, one of which has a gate valve. They join together and then separate before feeding the ballcocks.
The gate valve doesn't turn so I don’t know if it’s stuck in the open or shut position, however…
If I empty some water from a tank and the ballcock activates, then pipe B gets cold so I know water is flowing through it.

Anybody know why the ballcocks would be supplied like this?
Many thanks for any inspiration!
Pathetic diagram attached for your amusement and criticism.

 

[Harry Bloomfield]

Anybody know why the ballcocks would be supplied like this?
Many thanks for any inspiration!

Feeding both ballcocks/fill valves, from the one cold mains source, is the obvious way to do it - why not? B would seem to be the cold mains, up to the loft.

A, and the gate valve, would seem to feed somewhere else, possibly a toilet, electric shower, wash basin, or etc.. Try your trick with B, of running some water, and feeling the pipe temperature.

 

[Exedon]

As above my guess would be electric shower As the gate valve don't work I would change it for a decent lever valve and add another to cistern (tank) feeds.

 

[CouchPlato]

Thanks guys

I have double checked pipe A and it only goes to the ballcocks. Bit of a weird situation really.
All I can think of is that somebody in the past couldn't be bothered to replace the stuck gate valve so added a whole new pipe. But that woud be daft!

 

[endecotp]

I have double checked pipe A and it only goes to the ballcocks.

But where does the *other end* of that pipe go?

 

[CouchPlato]

But where does the *other end* of that pipe go?

Good question. Unfortunately the start of the pipe is burried behind plasterboard so I don't know for sure but I can only assume it's connected to the mains water supply. Could it be connected to something else?

 

[Harry Bloomfield]

Good question. Unfortunately the start of the pipe is burried behind plasterboard so I don't know for sure but I can only assume it's connected to the mains water supply.

Trace it, in the plaster, with a metal detector. Have you checked yet, whether it might feed/have fed, an electric shower?