Mystery of the plastic pipe filling in to the Cold Water Tank

[spader]

That is the old cold water tank in the loft I have been working on few days. The mains rise pipe is visible with the newly installed ball valve, and the old gate valve on the pipe. But there is a grey plastic pipe also connected to the pipe with a plastic TEE. I thought that grey plastic pipe was outgoing water feed to the 2nd floor electric shower from the cold tank.

But it is not. It appears that the pipe has been fillin in water to the cold water tank from the dowstairs kitchen immersion heater boiler. Because with the new ball valve and the old gate valve shut totally, there is still water coming into the tank, and it must be via the grey plastic pipe. If this is the case, what would have been the purpose of the grey pipe fliing water to the cold tank, when there is already the mains rise pipe for filling in water into the tank?

Was it necessary or even essential part of the whole system? How and why? If not, what was it for? Does it need to be there filling in water to the tank? Could it be taken out? Thanks.

 

[motorbiking]

Could it be that it goes the other way and provides drinking water to a bathroom?

 

[denso13]

Was it necessary or even essential part of the whole system? How and why? If not, what was it for? Does it need to be there filling in water to the tank? Could it be taken out?

No way of telling from a photo. You'd really need to tracte it and see where it goes.

Because with the new ball valve and the old gate valve shut totally

Don't touch the gate vale feeding the cistern, you seem to have a full bore valve, with the yellow handle, which you should use instead.

 

[spader]

No way of telling from a photo. You'd really need to tracte it and see where it goes.

Don't touch the gate vale feeding the cistern, you seem to have a full bore valve, with the yellow handle, which you should use instead.

When both the full bore valve and gate valve are totally shut, water still fills into the tank. It must be from the grey plastic pipe I presumed. When downstairs immersion heater boiler was totally drained, the filling-in to the cold water tank totally stopped.

Initially I thought the old gate valve was faulty, and installed the new full bore valve (yellow handled one). Now I am suspicious that the gate valve was not faulty at all. It was the water from the grey pipe kept filling in the cold water tank?

 

[denso13]

It was the water from the grey pipe kept filling in the cold water tank?

Doubtful, but if you can get photos from the other end of the grey pipe someone can advise better.

 

[CBW]

How does the water fill into the tank, Via the float valve, or does water just rise?

 

[spader]

How does the water fill into the tank, Via the float valve, or does water just rise?

From the float valve.

 

[CBW]

From the float valve.

Seems likely to be the grey pipe then, as per above, trace the pipe.

 

[spader]

How does the water fill into the tank, Via the float valve, or does water just rise?

Cannot trace where the plastic pipe is going to or connected to. It goes into the floor of the loft and buried into the glass firbe insulation piles. Downstairs in the kitchen where the mains water is coming in and the immersion heater boiler is are all the copper pipes.

Seems likely to be the grey pipe then, as per above, trace the pipe.

The only clue I have seen was when shut down the mains water valve and then drained the immersion heater boiler, the filling-in to the cold water tank totally stopped. Not sure, if it is connected somewhere around the immersion heater boiler. The boiler is wrapped securely with the insulation paddings.

 

[terryplumb]

Disconnect the plastic pipe and cap it ,together with the Tee ,cap that too.
Then see what does or doesn't work.
The copper pipe going to float valve rises above the tank ,is it capped ? I can't see from your pic what purpose it serves ?

 

[spader]

Disconnect the plastic pipe and cap it ,together with the Tee ,cap that too.
Then see what does or doesn't work.
The copper pipe going to float valve rises above the tank ,is it capped ? I can't see from your pic what purpose it serves ?

It is capped. I was wondering why it is raised up too.

 

[spader]

Close-up photo of the plastic pipe TEE.

 

[spader]

Disconnect the plastic pipe and cap it ,together with the Tee ,cap that too.
Then see what does or doesn't work.
The copper pipe going to float valve rises above the tank ,is it capped ? I can't see from your pic what purpose it serves ?

Close-up of the raised end of the mains rising pipe. It is capped.

 

[terryplumb]

I can't see any reason for that to be there ,it serves no purpose...odd !

 

[denso13]

Typical old trick to try and stop a water hammer by creating an air buffer. Never really worked as the water absorbed the air in the pipe.