Float valves which are OK if submerged

[tin...@isbd.co.uk]

I'm after a float valve of some sort which will not get damaged if it
is completely submerged. I want to have a tank which is mostly filled
from local sources of water but, if the local sources dry up, then the
float valve will maintain a foot or so of water in the bottom of the
tank from the mains. (I guess there will have to be strict non-return
precautions to conform to water byelaws too)

So, I need a float valve that won't mind being underwater, I suspect
that the 'standard' sort of cold water tank valve with a big spherical
float won't survive being under water.

Would a Torbeck valve be OK, or do they include the flushing mechanism
which I don't need?

--
Chris Green

[Andrew Mawson]

<tin...@isbd.co.uk> wrote in message
news:qvrpc7-...@chris.isbd.net...

You could used the low pressure diaphragm switches (*) used to set the
levels in washing machines, and have them controlling solenoid
valves - again from washing machines - so not only is the switch not
submerged, but the two sources of water can be totally isolated.

AWEM

(*)They use a column of air trapped in a tube, as the level rises so
does the pressure in the tube and the switch triggers - usually have
two independant set points that are tweakable with a little screw

[Dave Osborne]

As Andrew said, I would be inclined to use an electrical solution.

A float switch like this:

http://www.maplin.co.uk/Module.aspx?ModuleNo=12167

And a solenoid valve from a washing machine.

Oh, just found this: - perfect

http://www.halstedrain.com/Mains%20Water%20Top%20Up%20Valves.pdf

Seems to use a washing machine solenoid valve and a tundish for
non-return isolation.

[Dave Osborne]

Doh, just noticed page 2 of the pdf where there is a non-electrical
solution as well. Mechanical float valve on a piece of string. Clever!

[tin...@isbd.co.uk]

I'd rather not have a power (electrical) operated valve if I can avoid
it. I could do something similar to what you have described with a
float switch which is definitely OK submerged.

--
Chris Green

[tin...@isbd.co.uk]

That's exactly what I want, maybe I can simply add a bit of string to
a 'conventional' float valve of some sort. It does look as if the
valve they're using is quite like some of those available from BES.

I just get this nasty feeling that Halsted Rain charge a silly amount
for the device.

--
Chris Green

[tin...@isbd.co.uk]

I had a set-up which did *exactly* this, my design was amazingly like
what's described in the above link to a PDF, down to using a similar
plastic box to put it in.

However they don't survive all that long in an outdoor environment,
even in a shed (which is where mine was). The combination of
occasional freezing and our very high mains water pressure soon breaks
something.

(I guess I may have the same freezing problem with any sort of float
valve but at least they're cheaper)

The www.halstedrain.com site is a bit worrying, no indication of
prices anywhere that I can see.

--
Chris Green

[Tim Watts]

On 24/05/10 14:22, tin...@isbd.co.uk wrote:

>
> That's exactly what I want, maybe I can simply add a bit of string to
> a 'conventional' float valve of some sort. It does look as if the
> valve they're using is quite like some of those available from BES.
>
> I just get this nasty feeling that Halsted Rain charge a silly amount
> for the device.
>

Alternative simple idea: Brass cistern valve and extend the arm
downwards? Could be done with the vertical extension being a bit of

a) 15mm copper pipe, hole drilled in one side near the end;

b) Cut off float and 2" of brass arm;

c) Insert remaining arm from valve into side of copper tube and solder;

d) flatten other end of copper tube round the bit of arm that takes the
float and solder there.

Then you have:

====
=====-------------||-
==== ||
||
||
||
||
||
||
||
||
||
||
||
||
||
||
||
||
|
O
O O
O O
O

If the valve and arm are brass, I don't see why this shouldn't work. The
turning moment on the valve will only be a little worse than a normal
mode ball valve where the float becomes fully submersed (as could happen
in a CH expansion+fill tank)

And brass valves are highly maintainable. If the vetical drop is long,
it might be necessary to put a side baffle in to constrain the float to
vertical movemnet to reduce twist stress on the valve arm hinge.

--
Tim Watts

Hung parliament? Rather have a hanged parliament.