Plumbing problems

Flobberchops

Hi all, here's the situation.

We have a cold water storage tank in the loft. Lately it's been so persistently noisy that it's been keeping us up at night. On investigating, the water level is as low as it possibly can be and the noise is caused by the water cascading down from the inlet (sorry, don't know the terminology). It's exiting the storage tank as fast as it's entering meaning the water level never rises. The tank has three outlets, the upstairs cold supply is one of these three and by plugging each outlet in turn I was able to determine which it is. I don't know what the other two are but I believe our downstairs bathroom is supplied by this loft tank. The kitchen seems to be supplied direct from the mains.

Another issue we've had is that the upstairs cold water supply (I.e. Fed by the storage tank) sometimes dries up, leaving us with just scalding hot water. I have thus far assumed this is air locking and I've been able to fix it by obstructing the bath mixer tap and turning both knobs. Cue lots of gurgling and the cold supply is usually restored.

So far we have assumed the tank-emptying leak is caused by a dodgy stopcock on the downstairs toilet . Even in the up most position the stopcock doesn't stop the flow of water so it's constantly overflowing from the cistern into the bowl. Plumber has been booked for a couple of weeks time (council property).

However, my first question is, could this slow leak in the downstairs toilet really be accounting for the permanently empty loft tank? And if so, is there some way to isolate this? Are there typically valves along the supply line? I would much sooner have one toilet out of action than Niagara Falls above my head while I'm trying to sleep at night.

Second, could this leak have anything to do with my hot water system? I've recently had my gas boiler serviced and it's a bit hyperactive. It was initially really hot, almost boiling the water. I have no idea how this works but I've heard of boilers "dumping" water, could that be happening ? We have an electric immersion heater upstairs, currently not switched on, and a gas boiler in the kitchen.

The gas boiler is operating at normal pressure and there is no overflow from the loft tanks overflow pipe (as previously mentioned the water level is rock bottom, at no risk of overflow).

Any clue how I could fix this? It's driving me nuts. Many thanks in advance.

southcoastrgi

My concern would be where is all this water going ?

EachPenny

Flobberchops wrote: »

However, my first question is, could this slow leak in the downstairs toilet really be accounting for the permanently empty loft tank? And if so, is there some way to isolate this? Are there typically valves along the supply line? I would much sooner have one toilet out of action than Niagara Falls above my head while I'm trying to sleep at night.

It depends what you mean by 'slow'.

But if your mains pressure at the tank in the loft is not great, it is possible that the flow into the tank is less than the rate that a toilet might refill. If the valve in the toilet is allowing full-flow into the cistern and overflowing into the bowl then yes, it is possibly the cause of your ever-emptying tank in the loft.

Have you looked underneath the toilet cistern where the supply pipe goes in? There is usually a valve there - possibly one which you need a screwdriver to turn - which should shut off the supply to the toilet.

Flobberchops wrote: »

Another issue we've had is that the upstairs cold water supply (I.e. Fed by the storage tank) sometimes dries up, leaving us with just scalding hot water. I have thus far assumed this is air locking and I've been able to fix it by obstructing the bath mixer tap and turning both knobs. Cue lots of gurgling and the cold supply is usually restored.

Does the hot water keep flowing for a time, or does it soon run out as well?

If the tank in the loft empties completely then both the cold and the hot should stop running. For safety reasons, the draw-off for the hot water is normally placed a couple of inches higher than the cold draw-off... so the hot water will stop before the cold. If the two have been placed at the same level then it is possible that you'll still get hot running when the cold runs out.

I'm doubtful that an airlock would be the problem - if you have the cold tap turned on there is an outlet for air/water at a lower level that the water in the tank in the loft. In normal circumstances that should be enough to get at least some water flowing out... but by the sound of it your plumbing is far from 'normal'.

Flobberchops

southcoastrgi wrote: »

My concern would be where is all this water going ?

Unless some "dumping" mechanism is at play I'd have to conclude it's being discharged down the toilet overflow at a rate of several gallons a day.

Jonesya

Flobberchops wrote: »

Unless some "dumping" mechanism is at play I'd have to conclude it's being discharged down the toilet overflow at a rate of several gallons a day.

Sounds more like several gallons a minute if the tank is draining quicker than the valve can fill it.

To the Op, if the leak is as bad as it sounds then this isn't something that can wait several weeks, it needs fixing promptly, particularly if you are on a water meter as this could end up costing you quite a bit.

Flobberchops

EachPenny wrote: »

It depends what you mean by 'slow'.

But if your mains pressure at the tank in the loft is not great, it is possible that the flow into the tank is less than the rate that a toilet might refill. If the valve in the toilet is allowing full-flow into the cistern and overflowing into the bowl then yes, it is possibly the cause of your ever-emptying tank in the loft.

Have you looked underneath the toilet cistern where the supply pipe goes in? There is usually a valve there - possibly one which you need a screwdriver to turn - which should shut off the supply to the toilet.

Does the hot water keep flowing for a time, or does it soon run out as well?

If the tank in the loft empties completely then both the cold and the hot should stop running. For safety reasons, the draw-off for the hot water is normally placed a couple of inches higher than the cold draw-off... so the hot water will stop before the cold. If the two have been placed at the same level then it is possible that you'll still get hot running when the cold runs out.

I'm doubtful that an airlock would be the problem - if you have the cold tap turned on there is an outlet for air/water at a lower level that the water in the tank in the loft. In normal circumstances that should be enough to get at least some water flowing out... but by the sound of it your plumbing is far from 'normal'.

On reflection the busted toilet stopcock could account for all the water. It looks visually like "just a trickle" but that, alongside normal household water usage, could possibly explain it.


Yes, there was a screwdriver valve! I was looking for something with an obvious knob or handle, but turning off the toilet supply seems to have done the trick. Good idea, thanks for that.


The hot water *seems* to run indefinitely after the cold stops, but I haven't allowed it to run long enough to test that. It could just be residual water in the system. The three pipes fed by the loft tank are all at the same level - "unusual" seems to be a theme in my house.


Many thanks again for the feedback

Flobberchops

Jonesya wrote: »

Sounds more like several gallons a minute if the tank is draining quicker than the valve can fill it.

To the Op, if the leak is as bad as it sounds then this isn't something that can wait several weeks, it needs fixing promptly, particularly if you are on a water meter as this could end up costing you quite a bit.

I don't know, the rate of flow is quite low in the loft tank. Having plugged the leaky outlet it took several hours to fill to the point the stopcock turned the supply off.


It seems to be resolved for now (in a very stop-gap kind of way), but I dread to think what my next water bill will be like.

Jonesya

Flobberchops wrote: »

I don't know, the rate of flow is quite low in the loft tank. Having plugged the leaky outlet it took several hours to fill to the point the stopcock turned the supply off.


It seems to be resolved for now (in a very stop-gap kind of way), but I dread to think what my next water bill will be like.

Well that also points to another potential fault, that the float valve on the tank may need repairing because it should fill it a lot quicker than that. They have a rubber valve inside which can get stiff with age and not fully open, so it fills with a trickle.

Be worth getting the plumber to check it at the same time.