Black magic, I always think. Most of the DIY books have an explanation.
Ours did the same last week. It was a tiny bit of grit in the needle- sized hole in the outer cap - the hole that gets covered by the small circular rubber pad on the float arm attachment. I used a needle and air to clear it...at 12.30 a.m.!
It's what's called an equilibrium valve. The basic principle is that water pressure bears on both sides of the rubber diaphragm but there's more surface area exposed to the water on the side that presses the diaphragm against the inlet shutting off the water flow. But on that side there's a tiny hole - the one you see which gets covered by the tiny rubber bung attached to the float arm. When the float drops and uncovers the hole it takes away the pressure holding the valve shut and water runs through the valve, filling the cistern until the float rises and closes the hole whereupon the pressure on that side closes the valve again.
Until the hole gets blocked...they are very prone to dirt, etc. When they've been repairing water mains nearby, or when they suddenly decided to fit an external stoptap without telling us, dirt got in and buggered it up...!
They work on the same principal as the air valves in an aircraft's equipment cooling and air conditioning system. I had to go on a weeks course to learn how it worked, but the most eye opening thing was how the cockpit cooling was done, just using engine bleed air to cool the crew down.
It works on the same principle as a fridge or air con unit by compressing the coolant (air) to make it warm and then letting it expand, so cooling it and dumping the heat. There were no motors involved, it was all done by air driven devices.
On Sun, 24 Jan 2010 20:33:05 +0000, "Peter Crosland" wibbled:
Thank you all. I'll be plumbing my new bog soon. It came with a Torbeck valve. It looks very fliddy. After reading this, I'm off to look for a better valve/float assembly.
Croydon valves (the sliding plunger) did, I suppose, keep a lot of handymen employed (hmmm....) but they were rubbish at gradually leaking. Torbecks, IMHE, have been utterly reliable, fast-filling and quiet. OTOH, I haven't lived anywhere with hard water in years.
At present I've inherited some crappy American thing (dark grey, float wraps the upstand pipe) and it just doesn't get on with a UK syphon. It starts to refill instantly, so that if you let it fill at anything more than a trickle it doesn't let the syphon break and so it's continually semi-flushing indefinitely. Trying to throttle it with the service ballvalve makes it noisy, slow and requires fiddling from time to time. I have no intention of fitting the matching US-style flapper valve, lest the unquiet spirit of Thomas Crapper return and haunt me when that starts wasting water..
Agreed. Because the float only has a very short arm, it's only in the water for the last little bit of fill - so you get full flow until the cistern is virtually full, whereas a conventional float valve starts to shut off much earlier.
Torbecks have a spiral thingy to reduce the flow (a fine thread one for HP in and a coarse thread one for LP) that pushes into the inlet pipe. Very effective and quiet, and can be cut down if flow is too low.
I fitted one in a moment of madness, only lasted two years before it leaked. When the replacement leaks (when, not if!) it will be replaced with a syphon.
Same here nor problems at all fast fill and quiet. I wouldn't put one on a loft tank without first checking the over flow can handle the flow rate, as per the instructions...
The one I've now just replaced (wasn't worth fiddling with IMO) had quite likely been there since the bathroom was installed - 20 years? The one I fitted in my old house new cistern worked fine for about 5 years before I moved here.
Anyway, I'm not sure an alternative valve would fit. It is a shallow depth , built in cistern so there isn't much space in there.
Anyway, thanks folks i understand how they work now.
I'm with you about liking my Torbeck, the water either runs full rate or not at all, rather than a ball balve progressively reducing the rate to a dribble before the level is high enough to prime the siphon.
The same toilet has got a "Pacific" siphon with a wrinkled rubber seal and I can't get a replacement.That can be a nuisance, good job I'm not on a meter.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.