Rainwater Har & cistern valve.

karltimber

Hi,
just completing my rainwater harvesting project.

It is connect to the corner of the house where I can isolate the d/s toilet, wm and 2 outside taps.
Put in toilet connection yesterday, and when flushed the auto-pump beside the tank kicks in and refills the cistern. all good.

but when the cistern has filled, every few seconds a small burst of water comes into the cistern. The pump does not do this, and happens even when pump is turned off.

so I'm guessing the pressure from the water tank (30m up the garden) is just a little too much for the cistern inlet diaphragm. and lets a small amount of water in every few seconds.

so - how to reduce the water pressure in the line or get a stiffer diaphragm for the cistern ??

I understand that turning a ball-valve slightly open is no use as the pressure is still the same.

any ideas

K

corkgsxr

Smaller nozzle for higher pressure.

Or fit likes of fluidmaster valve. There designed for high pressure

karltimber

Thx GSX

The pressure isn't that great but just probably over what the cistern diaphram can hold back.

would something like this work - here.

reduce the inline pressure of the water.

might also try a few manual fixes tomorrow - to try and get a more robust seal on that valve when it closed.

corkgsxr

You can't get a more robust diaphragm. Just different nozzle sizes.

A fluidmaster ballcock is only 20 Euro. Works for all pressures

North West

Hi Karltimber
On the automatic controller on your pump, you should be able to reduce the pressure from there. Does your controller have a flow regulator? Most do, check your manual to see is there a flow regulator on the controller.
NW

karltimber

North West wrote: »

Hi Karltimber
On the automatic controller on your pump, you should be able to reduce the pressure from there. Does your controller have a flow regulator? Most do, check your manual to see is there a flow regulator on the controller.
NW

This push of water happens even when the pump is off. So the seal as such on the cistern cannot hold back the pressure of the tanked unpumped water.
Will take pic of seal.

K

nmacc

Sounds like something other than too much pressure tbh.

Even if the storage tank in the garden were 30m straight up, that would only be 3 Bar and an ordinary ballcock should have no problem with that. Is there a pressure vessel and non-return valve on the pump perhaps?

As corkgsxr points out, a Fluidmaster is a cheap fix, but make sure the water is clean, as the small aperture in the Fluidmaster is easily blocked by sediment, so you might find yourself frequently cleaning the filter that comes with it.

karltimber

This is the type of cistern setup.
Under house water, all works fine.
When the lever is lifted water stops.

But when on unpumped rain water. It keeps flowing from under that Sq cover.
There is a little rectangular rubber seal under that Sq cover that seems to be letting through the rain water. Again unpumped.

But stops the house water, when that's the source.

How does this type of valve work. No real cutoff mechanism inside ?
Thx

nmacc

Ahh!

The type of ballcock you have is operated by the pressure of the incoming water. That is, lifting the float does not, of itself, shut off the supply. A very fine hole allows through a bleed of the incoming water. When the float lifts to the closed position the small bleed of pressurised water is applied to a diaphragm. The relatively large area of the diaphragm acts like a lever and shuts off the water flow.

I don't know exactly what is happening in this case, but I suspect that when fed with mains water the pressure is constant and therefore the valve shuts reliably. It is possible that when fed with rainwater the pressure is either low or inconsistent, which allows the valve to drop open every so often. If the problem is simply low pressure then a Fluidmaster might do the trick as the manufacture claims they operate over a wide pressure range, but I've found them slow to fill at low pressure.

If your pump is pressure driven then the answer might be a pressure vessel on the line between the pump and the ballcock with a decent non-return valve. That way a consistent pressure would be maintained in the line and the ballcock should be held off....... - it says here

karltimber

nmacc wrote: »

Ahh!

The type of ballcock you have is operated by the pressure of the incoming water. That is, lifting the float does not, of itself, shut off the supply. A very fine hole allows through a bleed of the incoming water. When the float lifts to the closed position the small bleed of pressurised water is applied to a diaphragm. The relatively large area of the diaphragm acts like a lever and shuts off the water flow.

sounds like thats the way it operates alright. a small piece of rubber flaps over the inlet. and it takes about 1 second to actually turn off the flow.
Good to know. Ironic that an auld ballcock would probably work better.

Any particular type of Fuildmaster - this ??

A more mechanical system hopefully will stop the flow and not rely on pressure.

corkgsxr

karltimber wrote: »

sounds like thats the way it operates alright. a small piece of rubber flaps over the inlet. and it takes about 1 second to actually turn off the flow.
Good to know. Ironic that an auld ballcock would probably work better.

Any particular type of Fuildmaster - this ??

A more mechanical system hopefully will stop the flow and not rely on pressure.

The type you have is a high pressure valve. Iv found the fluidmaster to be the best of those type.

I think 3 bar is too high a pressure for a regular ballcock

The one is the right type

karltimber

corkgsxr wrote: »

The type you have is a high pressure valve. Iv found the fluidmaster to be the best of those type.

I think 3 bar is too high a pressure for a regular ballcock

The one is the right type

should have believed you from the start

a more mechanical cutoff valve should do the trick.
will report back when installed.

Thx
K

karltimber

Hi folks,

update: that worked a treat.
water stops due the mechanical nature of the cistern valve - ie fluidmaster

Thx