It's more correct to say that water mixing valves OPEN when the hot or cold solenoiods in them are energized. That's because their default position is closed, so they remain closed unless and until their solenoids are energized, allowing pressure in the water supply hoses to open them.

The water hammer that can happen when a washing machine, dish washer or toilet tank stops filling is due to the fact that the diaphragm in each valve closes very quickly. It's because of this that you typically see surge arrestors on the water supply piping going to washing machines.

Back when they used to sell overhaul kits for washing machine water mixing valves, I overhauled the water mixing valve on my main floor washer. The hot and cold springs that push the plug back into the diaphragm when the coil is de-energized aren't any bigger or stronger than the springs you typically find in an inexpensive ball point pen.

This image explains how the water mixing valve in a washer works fairly well:



Water comes in through the hoses and filtration screens on the right hand side.

The rubber diaphragm rests on a plastic seat. Water flows through that seat to get into the washing machine wash basket.

The water pressure is the same on both sides of the diapragm, but the area occupied by the seat reduces the area over which that pressure is applied on the far side of the diaphragm.

So, as long as the machine is off, the pressure equalizes on both sides of the diaphragm, but since force = pressure X area, there's a net force pushing the diaphragm down tightly onto the seat so that water can't flow into the washer.

When someone starts the washer, the hot, cold or both hot and cold solenoids are energized. This pulls the brass plated iron plug out of the hole in the middle of the rubber diapragm. When that happens, the pressure on the large area side of the diaphragm is released and the city water supply pressure on the small area side of the diaphragm pushes the diaphragm off it's seat. Water then flows under the diaphragm into the washing machine.

When the pressure switch in the washing machine senses that the washer is full, it stops the flow of electrical power to the hot and cold solenoids so that they are no longer pulling the brass coated iron plug in. The spring then pushes the brass coated iron plug out so that it covers the hole in the middle of the rubber diaphragm.

The water pressure then equalizes on both sides of the rubber diaphragm, and because the area of the seat reduces the area exposed to that pressure on one side of the diaphragm, there's a net force pushing the diaphragm down onto the seat so that water flow into the washer stops.

Here's what a water mixing valve for a washing machine typically looks like:



The two supply hoses you connect to your washer actually screw on to the mixing valve itself. Each solenoid is energized depending on whether you set the machine for a hot, cold or warm wash. The water enters at the two male threaded hose connections and leaves via the smaller tube on the opposite side of the valve.

Here's the water valve for a dish washer:



There's only one solenoid because you only supply hot water to your dish washer.

And, a toilet ballcock works exactly the same way, except that it uses the movement of the float to pull the plug out of the rubber diaphragm when you want water to flow into the tank, and push it back into the rubber diaphragm when you want to stop filling the toilet tank.

There you have the dirt on toilet ballcocks.

On Tue, 2 Jul 2013 08:09:40 +0200, nestork
wrote:


micky;3087051 Wrote:

No, I don't believe the city water pressure has anything to do with
closing the valve. It's the water level in the tank, which raises
the float, which is connected to the valve, that closes the valve.


No, it really is the water pressure. Otherwise, why wouldn't your
washing machine start filling up with water the instant you unplugged
it?

Because a washing machine has a solenoid controlled valve - only open
when powered.


Right now I have the water valve just outside one of my toilets closed
almost completely. The water barely dribbles into the tank, and the
tank water level rises so slowly it takes an hour to fill. But when
it is almost full, the float** is high enough to close the valve.

**Not a metal float on an arm but something I bought just 10 years
ago, with a plastic float just above the valve mechnaism.. The very
common brand whose name I forget.


I think you'd get a lot better performance out of that fill valve if you
replaced the rubber diaphragm in it. I have seen toilets do that
before, but that was before I knew anything about plumbing. Still I
would try replacing the diaphragm in that fill valve and see if that
helps.

I don't think you understand. I think he has turned the water control
valve off to PROOVE that the fill valve works even with virtually no
pressure.

If you believe the closure is caused by the water level in the tank
raising the float, then wouldn't it make sense for flush valves to have
a large float at the end of a long float arm to generate the maximum
closure force. Why, for example, would designers make a fill valve with
very short float arms, such as in the fill valve below:


Because they can.. And old (style) ones DID use a long lever - the
new (style) ones are less trouble. (usually)
[image:
http://0.tqn.com/d/homerepair/1/0/R/...-ballcock.jpg]

And, wouldn't it make sense that a fill valve like the one above
wouldn't work nearly as well as something like this:

[image:
http://0.tqn.com/d/homerepair/1/0/o/...k-plastic.jpg]

In fact, you don't need much force to push a plug into or out of a
rubber diaphragm, and so there's no real advantage in having a large
float and a long float arm. If it was the buoyancy force of the float
that shut off the water flow, then EVERY toilet fill valve would have a
float the size of a large pumpkin on the end of a two foot long float
arm because that's what would work best.

On Tue, 2 Jul 2013 09:05:26 -0400, "Stormin Mormon"
wrote:

Washing machine valve is closed, unless the
power activates the solenoid which pulls the
valve open. I've never tried a washing machine
valve with low pressure cistern water. Would be
a fun test for someone to do and let us know
what was learned.
.
Christopher A. Young
Learn more about Jesus
www.lds.org
.


Depends what you call "low pressure cistern water" If it has a pump
it works fine.
.
"nestork" wrote in message ...

No, it really is the water pressure. Otherwise,
why wouldn't your washing machine start filling
up with water the instant you unplugged it?

On Tue, 2 Jul 2013 23:29:18 +0200, nestork
wrote:


micky;3087254 Wrote:

No, washing machine valves close when there is no power applied to
them. They have a spring, and it's probably pretty strong given the
thud that can sound through all the (cold water?) pipes in the house
when the valve closes suddenly.

Washing machine valve is closed, unless the
power activates the solenoid which pulls the
valve open.


It's more correct to say that water mixing valves OPEN when the hot or
cold solenoiods in them are energized.

Back when they used to sell overhaul kits for washing machine water
mixing valves, I overhauled the water mixing valve on my main floor
washer. The hot and cold springs that push the plug back into the
diaphragm when the coil is de-energized aren't any bigger or stronger
than the springs you find in a typical ball point pen.

This image explains how the water mixing valve in a washer works fairly
well:

[image:
http://static.howstuffworks.com/gif/...machine-2.jpg]

Water comes in through the hoses and filtration screens on the right
hand side.

The rubber diaphragm rests on a plastic seat. Water flows through that
seat to get into the washing machine wash basket.

The water pressure is the same on both sides of the diapragm, but the
area occupied by the seat reduces the area over which that pressure is
applied on the far side of the diaphragm.

So, as long as the machine is off, the pressure equalizes on both sides
of the diaphragm, but since force = pressure X area, there's a net force
pushing the diaphragm down tightly onto the seat so that water can't
flow into the washer.

When someone starts the washer, the hot, cold or both hot and cold
solenoids are energized. This pulls the brass plated iron plug out of
the hole in the middle of the rubber diapragm. When that happens, the
pressure on the large area side of the diaphragm is released and the
city water supply pressure on the small area side of the diaphragm
pushes the diaphragm off it's seat. Water then flows under the
diaphragm into the washing machine.

When the pressure switch in the washing machine senses that the washer
is full, it stops the flow of electrical power to the hot and cold
solenoids so that they are no longer pulling the brass coated iron plug
in. The spring then pushes the brass coated iron plug out so that it
covers the hole in the middle of the rubber diaphragm.

The water pressure then equalizes on both sides of the rubber diaphragm,
and because the area of the seat reduces the area exposed to that
pressure on one side of the diaphragm, there's a net force pushing the
diaphragm down onto the seat so that water flow into the washer stops.

Here's what a water mixing valve for a washing machine typically looks
like:

[image: https://www.midwestapplianceparts.co.../22003384.jpg]

The two supply hoses you connect to your washer actually screw on to the
mixing valve itself. Each solenoid is energized depending on whether
you set the machine for a hot, cold or warm wash. The water enters at
the two male threaded hose connections and leaves via the smaller tube
on the opposite side of the valve.

Here's the water valve for a dish washer:

[image:
http://b2bimg.bridgat.com/files/sole...g_machine.jpg]

There's only one solenoid because you only supply hot water to your dish
washer.

And, a toilet ballcock works exactly the same way, except that it uses
the movement of the float to pull the plug out of the rubber diaphragm
when you want water to flow into the tank, and push it back into the
rubber diaphragm when you want to stop filling the toilet tank.

There you have it. The ugly truth about toilet ballcocks.
You are describing a piloted valve - which is quite common, but is
NOT the only kind of water shutoff valve.

I googled "Piloted Valve" and here's what Wikipedia had to say about it:
Pilot valve:
From Wikipedia, the free encyclopedia

A pilot valve is a small valve that controls a limited-flow control feed to a separate piloted valve. Typically, this valve controls a high pressure or high flow feed. Pilot valves are useful because they allow a small and easily operated feed to control a much higher pressure or higher flow feed, which would otherwise require a much larger force to operate; indeed, this is even useful when a solenoid is used to operate the valve.

Pilot valves are often used in critical applications (i.e., emergency and safety controls) and are human-operated. They can be set up as a push-to-activate or dead man's switch.

Apart from the fact that the word "solenoid" appears in both my post and the Wikipedia excerpt, I see absolutely no connection between what I was describing in my post and what Wikipedia is talking about. We don't have TWO vavles here with the flow through one controlling the flow through the other, which is apparantly a prerequisite to having a "piloted" valve.

On Tue, 2 Jul 2013 23:29:18 +0200, nestork
wrote:


And, a toilet ballcock works exactly the same way, except that it uses
the movement of the float to pull the plug out of the rubber diaphragm
when you want water to flow into the tank, and push it back into the
rubber diaphragm when you want to stop filling the toilet tank.

This description has been bothering me for a day or so. Rather
than the plug going in and out of the diaphragm, I think the plug is
firmly fixed in the diaphragm, and the whole thing, the plug and the
middle portion** of the diaphragm move back and forth as one unit when
the water goes on and off. The valve itself is very close, on the
wet side of the diaphragm. The plug goes out of and in the rest of
the valve, depending on whether the water is flowing or not, and a
flexible diaphragm is needed so that water won't come out of the top
of the valve, like it would if there were just a hard piece with a
hole just big enough for the plug. That would still leak but a
diaphragm that hasn't ripped or cracked yet won't.

**The circumference of the diaphragm is immobile, in between the two
pieces of the case, usually with screws every 30 or maybe 120 degrees
around the circumference, holding the top, the diaphragm, and the
bottom together.

I used a lot of words because I havent' found an adequate picture.

There you have it. The ugly truth about toilet ballcocks.

New guy here.

I read through this entire thread, since I am interested in the same as as the OP.

I note that some suggested a pump. In my situation for example, at a camp there is no electric except for occasional run of a generator. Solar power is available but very limited as well, only run a few LED lights.

The fundamental problem is filling a toilet with gravity at very low head, 3 foot above the tank top. I have tried ballcock as well as the newer short arm fill valves. Neither will shut off.

Using electric for pumping or valve control is out of the question. Current method is to turn on the manual valve to the toilet when posterior is on the seat, tank will mostly fill while on the throne. Flush. While washing hands leave manual valve on. When handwash is done turn off manual valve.

Rinse repeat.

So where does one find a fill valve which will function on a very low head water system?

On Sunday, June 30, 2013 7:49:42 PM UTC-4, wrote:
Hi,

I've installed a large tank in the yard, above the height of my toilet water closet. I'm filling the large tank with water from a sump pump.

Problem is this:

The gravity feed is very low pressure, so the regulator in the toilet water closet doesn't function using the gravity feed supply. However the regulator works fine when using the city supply for water.

Is there anyway to adjust the regulator in the toilet water closet to work with very low pressure water supply?

I'm back, just read most of the replies.

What I ended up doing is taking the shut off valve a part (it was easy) and removing the large rubber rings that are used to quiet the water flow. I think that's what they're in there for. I left only the small one that actually shuts off the water when the ball arm is lifted to the top of the tank by the water height.
So the low water pressure works now and I've been using the system all month.
It takes about six minutes for the toilet tank to fill enough for another flush.
With the large rings removed I can hear the water trickling into the tank, but I don't mind as it lets me know its working okay.
Thanks for all the input.

Great to have the final feedback

Ahh, finally.

I finally found the proof needed to show that toilet ballcocks (or at least the FluidMaster A400) work the way I described earlier in this thread. That is, by using the water pressure in the supply line acting on different areas on each side of a rubber diaphragm to allow or prevent flow of water into the toilet tank. Contrary to popular belief, the A400 does NOT use the buoyancy force of the float to stop the water flow, and so far as I know, no ballcock does. That was a contentious issue in this thread.

Readers are referred to Fluidmaster's own tech support page at this URL:

http://support.fluidmaster.com/reald...alve_works.pdf

The above PDF file explains how the diaphragm (which they call the "seal") is pushed up and down by water supply pressure acting on each side of it. And, most importantly, that the buoyancy force of the float is used only to raise and lower the "control stem" (which I called a "plug"), and whose movement effectively plugs and unplugs a hole in the diaphragm to release the pressure on the large area side of the diaphragm.

It's good to know how this kind of water closure system works because you find it all over the place in different products. Since the last time I posted, it's also come to my attention that Ondine bathtub diverter spouts also use a similar closure system to stop water flow out the tub spout, thereby forcing the water to go out the shower head.

Erness:
In the above PDF, you'll see that the rubber diaphragm is flexing in image #2. What I was trying to explain to you in an earlier post was that perhaps the reason why your ballcock wasn't closing was because the water pressure wasn't sufficient to cause the diaphragm to flex. That is, the rubber diaphragm is resilient and it takes a small but finite amount of force to cause it to flex. I was thinking you simply didn't have enough water presssure available to you to cause that rubber to flex. And, without the diaphragm flexing (as the result of movement) then the ballcock can't work properly. I expect what's happening is that the resilience of the rubber is causing the diaphragm to stay in the closed position, but not with sufficient force to close tightly so as to prevent water flow. So, what's probably happening is that water is merely "leaking" under the diaphragm into your tank because the force pushing down on the diaphragm to stop the flow isn't sufficient to overcome the force needed to flex the rubber.

If you ever need to replace the ballcock, try the kind I suggested earlier in this thread. I expect it'll work much better for you because it uses the hydrostatic pressure of the water in the tank to open and close the ballcock, not the water supply pressure. Your existing ballcock uses the water supply pressure, and that's problematic if you have almost none.

Clare_Snyder: The water valves in clothes and dish washers work much the same way, only they use a solenoid to pull a plug out of the diaphragm and a spring to push it back in.

This is a really old thread but in case someone else views it, Jobe makes a flow valve that works with any water pressure above zero. It is sold on Amazon. I use it for gravity fed water troughs for my goats but it would work great inside a gravity fed toilet.