Any plumbers here?
 

I have an "old" cold water system with a storage tank in the loft. The overflow started dribbling a good while ago so I replaced the diaphragm in the float valve and it has been fine for a couple of years but its not shutting off fully again. Replaced the diaphragm but it made no difference :shrug: I was going to replace the float valve itself but its located at the rear of the tank and the inlet pipe to valve connection is all but inaccessible.

Any suggestions why a new diaphragm hasn't cured it?

You may have increased pressure from the mains. You could try bending the float arm down a bit too but a new ball c*ck sounds to be the most likely cure. (Hope that gets through the naughty filter!)

Pressure hasn't changed, not noticeably. The arm is bent anyway, dumb set up, the valve is above the level of the overflow. I suspect I'm going to have to find some way of getting access to the rear of the tank and replace the whole valve, its at a low section of the roof, no "flooring", need to crawl into position then try to balance myself crouched down on the rafters! Recipe for disaster!

We once had a loft tank with a ball valve and there came a time when changing the rubber washer did not fix the problem entirely because the seat of the valve it sealed against deteriorated with age too. We changed the valve and all was well but we eventually opted to replace the system with a new one and a combi boiler. Given what you have said about access and maybe your health and age previously Steve it might be worth considering getting someone in to do the job for you. I find myself doing this more often as time goes by because where the mind is still willing the body often protests quite strongly - and for quite a while after when I get it wrong. :getmecoat:

If you can see the rafters (do you really mean ceiling joists?) you have not got enough insulation!!

Its a slightly weird, hybrid, system. Mains water feeds a combi boiler, kitchen etc, the tank seems to only feed the cold tap on the bathroom sink and toilet, maybe the shower as well :shrug: I object to getting someone in for what is a simple job, its just getting at the bl00dy thing, dumb idea to put it at the back of the tank! The valve is entitled to be tired, it probably dates from when the cottages were originally renovated about 50 years ago.

No, I can't see the joists but I know there's no flooring in that area. When we inherited the place from my parents there was only a small floored area in the middle of the loft but I increased the size for more storage space.

Buy a new valve and split it at the large nut so the tail and body separate. Do the same with the existing one.You will need to hold against the body while undoing the large nut.Introduce the new valve body to the existing tail and tighten.Job done,no need to undo water connection.Just take care you don't loose the aperture and piston from the new valve while apart.:}

[QUOTE=stevestrat;2773608]Its a slightly weird, hybrid, system. Mains water feeds a combi boiler, kitchen etc, the tank seems to only feed the cold tap on the bathroom sink and toilet, maybe the shower as well :shrug: I object to getting someone in for what is a simple job, its just getting at the bl00dy thing, dumb idea to put it at the back of the tank! The valve is entitled to be tired, it probably dates from when the cottages were originally renovated about 50 years ago.

From your description it would seem that your bathroom's cold plumbing is piped up as a low pressure system, ( tank fed ). This was sometimes done so that early mixer shower valves and bath mixer taps were operating on equal pressures when being used.
I assume that when the combi boiler was fitted the existing shower valve was not compatible to the new boiler, and therefore left to run on the low pressure set up.

A solution to your problem may be to change the shower valve to a combi compliant model, then reconnect your low pressure cold supply to the toilet, basin and bath back onto the cold main. You would then be able to terminate the use of the tank.

It sounds slot of work, but to connect the low pressure cold could easily be done in the roof space by redirecting the cold mains supply to the tank to connect onto the low pressure cold pipe from the tank.

Hope this makes sense.

Bite the bullet, get somebody in.--If, as you say, it's a simple job the cost will be low.

Don't injure yourself, it's just not worth it.--:D

I agree with Colvert, get a plumber in!