Attic cold water tank always taking water in

[richardb70]

Hi all experts, hoping you can help...

I've had the attic hatch opened up for the past month or so. The ballcock valve and float had to be replaced on the cold water tank as it was leaking all down the side (but that's another story). I was at work so a plumber did the necessary. I was up there every so often making sure the floor was drying OK, and saw that the F&E tank was now half-full so off to B&Q for replacement float valves etc. All good now (old systems!).

Anyway, while I've been coming and going, I've noticed that there's a steady drip from the brand new float intake into the cold water tank, every 7 seconds or so. The level is not going up as far as I can tell - and is certainly nowhere near the overflow even after a weekend away. I've been all over the house looking for leaks (taps, toilets, under carpets etc), but no luck. Anything obvious I might be missing?

 

[seco services]

operate it by hand maybe just abit of muck stopping it shutting fully.

 

[JohnD]

yes, it could be grit.

or it could be that (if you dissembled it to change HP restrictor) you cross-threaded a nut and it is not tight. this easily happens if it is plastic (but not easy if it is brass)

Or you might have a leak somewhere which is drawing a little water, and the valve is topping it up. You will spot this if you press on the float to increase the water level by an inch or so, and the drip stops.

 

[IainWatson]

sounds like a small problem inside the valve, like the replies above hint.

Also, if you have a white plastic 90degree spout on the outlet from the valve - if that spout is cross threaded or not done up tightly enough (finger tight is fine) then a drip may come from within it's threaded housing and migrate to the end.

sounds more like the diaphragm/washer inside the valve aren't seated properly, perhaps faulked by swarf or grit.

good luck

 

[richardb70]

yes, it could be grit.

or it could be that (if you dissembled it to change HP restrictor) you cross-threaded a nut and it is not tight. this easily happens if it is plastic (but not easy if it is brass)

Or you might have a leak somewhere which is drawing a little water, and the valve is topping it up. You will spot this if you press on the float to increase the water level by an inch or so, and the drip stops.

Thanks guys, much appreciated. I don't think the water level's been rising at all (checked it last thing at night yesterday and first thing this morning) but I could be wrong. I'll have a play around with the valve tonight and see if there's an obstruction. Otherwise (gulp), I imagine the leak could be anywhere and I'd rather not have the house collapse on me.

 

[richardb70]

Hi everyone,

Well, I fiddled around with the float valve and eventually replaced it with a new brass one from B&Q to see if that made any difference. Unfortunately, not. It still drips every 6 seconds or so. Hold the float down to let water in, and the drip stops (as it does when I lift up the float).

So I'm thinking I have a slow leak somewhere (or some kind of really fast evaporation). Not being an expert myself, I'm pretty sure the cold tank only feeds the upstairs washbasin (no mixer), the shower unit (mixer), the bath (no mixer), the toilet and the hot water tank. No visible leaks in or on any of the above, or around the pipes I can see. Apart from digging up floorboards, am I missing anything/anywhere obvious?

It goes without saying that I haven't noticed any stains or bulging ceilings - yet!

Thanks in advance.

 

[Goldspoon]

Sometimes the valve takes a while to shut because the tank water level is not quite high enough to raise the float. So you get drip, drip, drip for a while...