pipe diameter

[ollybolly]

Hi,

The outlet from my washing machine is ~18-20mm diameter. You recommend using 1" (25mm) pipes for the Laundry to Landscape system. Do you think its likely to cause problems if I use 20mm poly pipe for my setup (since 20mm fittings are more readily available)?

Thankyou for the very informative site by the way.

cheers,

Olly

[oasis]

The line from your washer is only 1m long. The L2L distribution line can easily be 30+m long, which is considerably more (30x) drag.

A few thoughts:

1) If your washer is horizontal axis, measure the peak flow; if it is much less than 22 lpm 20mm should be fine.

2) If your line slopes steeply downhill, 20mm is better than 25mm, as the extra drag offsets the pressure increase at the lower levels.

3) You can put a 25mm x 20mm x 20mm bull head tee (available from dripworks) as early as possible in the system, and run TWO 20mm distribution lines, which will put no extra load on the pump relative to a 25mm line.