Overflow into cold water storage tank in roof

[Joshdhaliwal]

I am not an expert so please bear with me.

I noticed a few weeks ago water pouring out of the overflow pipe connected to the large cold water storage tank in my roof. This is not a property I am currently living in so I turned off the mains water supply to the tank because I thought I would let the tank empty so the build up of limescale could be cleaned.

Today I noticed the overflow pouring out water onto my drive again. I checked the tank in the roof and although the supply was off the tank was once again full. I did then notice the copper pipe which I believe to be the overflow from the immersion tank downstairs constantly trickling into the cold water storage. The trickle is cold water as my heating and hot water is currently off.

What seems to be the problem?

Secondly if I close the feed pipe which takes water out of my cold water storage tank the flow of water from the copper pipe with the bend in it increases. Confused.

Appreciate any help.

Josh

 

[diamondgas]

:welcome: to the forum Josh

Any chance you could take some pictures or maybe a drawing of what you're describing? Do you have two tanks in the loft as you're describing what sounds like a perforated coil

 

[snowhead]

Turn the main stop tap off , not the tank stop tap, and the water drip will stop.
You've got mains cold crossing over to the tank fed supply.

You've got a mixer valve somewhere, fed with mains cold and tank sourced hot and it's crossing over.

I see it a lot on commercial sites, but it would be unusual on domestic.

 

[Simon F]

Hello Josh,
is the feed and expansion tank for the central heating higher than the cold water storage tank?
if so, if you turn of the main stop tap, does the level of the f+e drop and the level of the cold tank rise?