"Terryc" wrote in message
...
Geoff & Heather wrote:
George,
What about 19 or 25 mm black poly pipe (depending on diameter of existing
WM hose. 91mm Poly pipe ie standard irrigation pipe is really cheap

Errr, no. AFAIK, that 19mmm cheap stuff is definitely NOT standard
irrigation stuff. It is thin wall stuff for the home market. It is okay
for low flow, low pressure situations, like trickle watering my vege
garden beds from 2m high tanks via a 19mm backbone around the fence

The really good stuff is much thicker, stiffer and expensive.
Unfortunately, I needed to buy it to join my two tanks for storage
balancing (aka the small one collects more water than the large one)

For his application, unless his washing machine feeds into a surge
tank[1], then he definitely needs a pipe FAR bigger than the outlet to the
washing machine. There must be a physical break so that atmosphere comes
in and allows the WM pump to run as designed.

The outlet on our washing machine is actualy 19mm internally, but it would
be unwise just extend the pipe as the extra 20 metres of pipe will
increase the resistance to flow by about 11 times[2], which is something
the washing machine water pump is not designed to handle.


[1]Another idea for a surge tank might be a vertical strip of 90mm
stormwater pipe (an economical buy) against the wall. You would need to
buy an end cap and glue it on, then glue/bolt on a hose socket at the side
on the bottom. Put a brick on the ground and sit the endcap on it. This
takes the weight. Hold in place with a couple of pipe brackets. You could
even paint it to match the wall. It is an effective surge tank and as it
fills up it, increase, the flow through the 19mm pipe or hose to the
garden lawn.

My rough calcs says that a 2m length would hold about 12L (YMMV[3]), which
should AFAIK be adequate for the general domestic washing machine.

[2] Actually,the volume of flow through a 22 metre pipe is 1/11 of the
possible volume through a 2m pipe, all other things being equal.

[3]3.1415x0.045x0.045x2000 = 50.08 L

Terry
Let me get this clear. You are saying that a 20m length of standard size
washing machine outlet pipe (the same diameter as I have on the WM outlet)
is too narrow? I am pumping about 900 mill above the bottom of the WM tub,
out a window and then a 2m fall off to the lawn below which is flat.

Your opinion is that this set up will not work?

If then I plump some form of surge tank (not being too sure what that is yet
but will find out), am I having to rely on gravity (the drop off from the
deck to lawn is about 700mm) to draw water out of the tank and on to the
lawn or will the wm pump continue to do this?

I have collected myself about 20 mm of identical size concertina hosing &
some couplings. I am set to go, apart from the somewhat important matters
like those above.

Thanks
Rob