Loss of water from cold storage tank All aspects of plumbing questions and answers, help, tips and information

[staf4d]

I have a problem with the cold water storage tank in the loft which drains to empty.

When we go away for a week we turn off the water at the mains, we also check that all the hot and cold water taps are all turned to off and that they are not dripping.

The toilets are filled from the mains supply, so I have ruled them out, the cold water tank only feeds my house and is not shared in any way. I have checked all the pipe joints and there is no leak, and there is no sign of any escaped water either inside the building or outside.

I have tried turning off the water at night and then checking the tank in the morning to notice that it has dropped about 1", so the water is going somewhere. I notice that the drain pipe at the bottom of the storage tank leads straight into the hot water cylinder and no where else.

So unless the water is escaping from central heating pipes under the floor boards (which will be a nightmare to get to) then I do not know where else to look.

Please help me solve this mystery. Thanks in anticipation

[PeteN]

If all your cold is from the mains, my first thought would be you're losing water from a feed to a hot tap somewhere. Are there any hot water pipes (not heating) downstairs that go under the floor or anywhere that you havn't noticed leaking? Or maybe you have thirsty squirrels in your loft!

[nitro23456]

this is a bit of an odd one....

Are you saying your CW tank ONLY feeds your hot water cylinder and no cold taps, showers, toilets etc?

If this IS the case and you dont have any dripping overflows or toilets that are in fact tank fed and overflowing into the pan then you MUST have a leak somewhere, or the water is being used by an appliance such as a dishwasher or dripping hot tap.

You dont have someone living in your loft drinking your water without you knowing do you? I say this as a joke but infact there was a case of someone who lived in someones loft for 4 months undetected!!

I don't see how it can be central heating related as this would be your F&E tank and not your CW tank which I presume you havent got mixed up?

Check the ceilings/floorboards/under the bath for signs of a leak. Is your heating working correctly?

[Dave From Leeds]

Try turning off your water at the mains then open a hot tap until it stops running. If the water tank you are referring to is then empty it confirms that the tank in question is in fact your cold water storage tank and that the water is probably being lost to your hot water system. Are you able to access all the pipes from the hot water cylinder to the hot taps to check for leaks?

If the offending tank is still full after the hot tap stops running then the tank that is emptying is the feed and expansion tank for your central heating system. If it is this one that's emptying there may well be a leak in one of your central heating pipes.

[bobplum]

hi
the bit i would worry about is the drain pipe going to the cylinder?
do you mean the overflow/warning pipe which normaly goes to the outside of the house or the cold feed to the hot water cylinder,this would normally terminate at the bottom of the hot water cylinder,this would then replenish the hot water

[staf4d]

[quote="PeteN"]If all your cold is from the mains, my first thought would be you're losing water from a feed to a hot tap somewhere. Are there any hot water pipes (not heating) downstairs that go under the floor or anywhere that you havn't noticed leaking? Or maybe you have thirsty squirrels in your loft![/quote]

Hi Pete

Thanks for your reply. There is a hot water pipe which feeds a tap, that either goes under or is embedded in the concrete floor of the kitchen extension. I will have to see if I can isolate this feed and then report back.

[staf4d]

[quote="nitro23456"]this is a bit of an odd one....

Are you saying your CW tank ONLY feeds your hot water cylinder and no cold taps, showers, toilets etc?

If this IS the case and you dont have any dripping overflows or toilets that are in fact tank fed and overflowing into the pan then you MUST have a leak somewhere, or the water is being used by an appliance such as a dishwasher or dripping hot tap.

You dont have someone living in your loft drinking your water without you knowing do you? I say this as a joke but infact there was a case of someone who lived in someones loft for 4 months undetected!!

I don't see how it can be central heating related as this would be your F&E tank and not your CW tank which I presume you havent got mixed up?

Check the ceilings/floorboards/under the bath for signs of a leak. Is your heating working correctly?[/quote]

Hi Nitro and thanks for your reply.

Yes the CW tank ONLY feeds the hot water cylinder, we do not have a dishwasher and there are no leaks from any of the taps, there is definately no one living in the loft.

I have not got the feed & expansion tank and the cold water tank mixed up, there is no evidence of any leaks anywhere in ceilings or the upstairs floorboards.
The CW tank is very large and any escape of water would be more than noticeable, and the central heating works fine.

[staf4d]

[quote="Dave From Leeds"]Try turning off your water at the mains then open a hot tap until it stops running. If the water tank you are referring to is then empty it confirms that the tank in question is in fact your cold water storage tank and that the water is probably being lost to your hot water system. Are you able to access all the pipes from the hot water cylinder to the hot taps to check for leaks?

If the offending tank is still full after the hot tap stops running then the tank that is emptying is the feed and expansion tank for your central heating system. If it is this one that's emptying there may well be a leak in one of your central heating pipes.[/quote]

Hi Dave and thanks for your reply.

I turned off the cold water at the mains and opened up the hot water taps and the CW tank drained to empty.

The only pipe that I can not trace for leaks is the one that is either under or imbedded in the concrete floor of the kitchen extension, which was built before I moved here.

[staf4d]

[quote="bobplum"]hi
the bit i would worry about is the drain pipe going to the cylinder?
do you mean the overflow/warning pipe which normaly goes to the outside of the house or the cold feed to the hot water cylinder,this would normally terminate at the bottom of the hot water cylinder,this would then replenish the hot water[/quote]

Hi Bobplum. Thanks for your reply.

When I say drain pipe I mean the cold feed that leads from the bottom of the CW tank to the bottom of the HW cylinder.

[nitro23456]

I presume the hot water pipes in the concrete of your extension were lagged properly? If not, my moneys on a corroded copper pipe caused by the concrete poured on top of it.

[nitro23456]

....just to add to that, you could drain the header tank and cylinder... isolate the now empty cylinder from the header tank by the gate/isolation valve on the cold feed from the header tank, fill the header tank and leave it.

If the level stays the same its a leak on your hot water side, probably as my post directly above!

[bobplum]

hi again
dont you just love a mystery
is this cold water tank in an area that is very warm in the day and cold in the night,i appreciate it may be in a loft but if there is a big temperature difference it could be just expansion and contraction
just a thought
bob