Dribbling ball valve

[MikeH]

The ball valve in my heating system F&E tank only allows a trickle of water to flow. This is fine for normal use, but it's a pain when flushing and re-filling the system because it takes so long to fill. The valve is the same as the type that I've seen used in toilet cisterns. The float-arm pushes a plastic plunger that in turn presses a rubber washer against the narrow end of a cone-shaped bit of plastic through which the water flows. The rubber washer is quite stiff and the hole through the cone-shaped plastic is narrow. This combination of the stiff washer and the narrow hole results in a very slow rate of fill.

Can anyone point me to a different design of ball-valve that allows a higher flow rate (without being so high as to overwhelm the capabilities of the overflow pipework).

Thanks,

Mike

[Dave Baker]

The plastic mechanism valves usually come with two alternative cones for high and low pressure systems. Maybe yours has the wrong one fitted. You could probably drill the hole out a bit bigger to cure the problem if that's what it is. I also vaguely recall some sort of adjustment with a plastic screw and nut under the arm from when I fitted mine many years ago but that may have just been for the shutoff position. Worth a look though.

Also are you sure the supply to the ball valve isn't restricted in some way by a stop c*ck somewhere that perhaps hasn't been opened fully?

Anyhoo, those plastic valves work fine if they're fitted right so no need to search out a better type. Just find out what's wrong with your one.

-- Dave Baker Puma Race Engines

Camp American engineer minces about for high performance specialist (4,4,7)

[MikeH]

There's no problem with the supply to the tank. Without the valve in place the flow is 'normal' for a mains tap.

I've had problems with these valves before, but never been able to see why the flow is so low, other than to attribute it to the design of the unit. I suspected that the rubber diaphragm might have hardened, but it's only 5 years old, so that doesn't seem likely. As yoy say, the adjustment feature sometimes found at the valve end of the arm is to control the shut-off point. Mine doesn't have one anyway because the arm is cranked so that the 'depth' of the ball with respect to the arm can be adjusted to achieve the right cut-off level.

Short of drilling out the cone or fitting one for a low pressure supply, I'm not sure what else I can do to the darn thing.

What counts as 'low' pressure. As far as I can remember the static pressure measured on the ground floor cold mains tap (many years ago) was about 40psi (1.25 bar?). Maybe I shoud try changing the cone for a low pressure version, but I'd prefer to change the valve for a different design if such a thing exists.

Mike

[TheTaffia]

I've seen the problem of poor flow through (what should be) fully open ball valves twice before, once in a ball valve in the header tank in the attic and once in a ball valve in a tradional (i.e. non button-type) toilet cistern. Both times the poor flow problem was caused by a blockage in the valve itself which is normally pretty easily pulled apart. It was a little stone jammed into the narrow part of the valve, only letting a small flow through.

It was getting really annoying waiting for the toilet to fill in the event of a two-flusher sitation occurring, IYSWIM!

HTH

Ross.

[MikeH]

Heck - I can't imagine how bad it would be if it were blocked as well :-)

I've already had it to bits (several times) and there are no foreign bodies, C/H crud, sludge, scale, etc, blocking it.

Any other ideas, anyone?

Mike