I wanted to use RO water to clean my windows using the pressure washer
as a pump.

It doesn't work with just a length of hose attached to the inlet.

However it does work with a £2.37 non return valve from toolsatan on the
end.

http://www.toolstation.com/shop/Plum.../sd2696/p77952

Fits well using a plastic pipe insert and just screwing up the
compression fitting.

Saves about £25 if you need one.

Be aware that it doesn't have a filter so don't use your water butt
without one.

On Monday, 16 June 2014 12:45:00 UTC+1, dennis@home wrote:
I wanted to use RO water to clean my windows using the pressure washer as a
pump. It doesn't work with just a length of hose attached to the inlet.
However it does work with a �2.37 non return valve from toolsatan on the end.

Any thoughts why? I would've expected anything that might impede the flow, however slight, can only make matters worse.

I would've thought that increasing the height differential between the pressure washer and water supply would be all that's required.

Mathew

On 16/06/2014 16:21, Mathew Newton wrote:
On Monday, 16 June 2014 12:45:00 UTC+1, dennis@home wrote:
I wanted to use RO water to clean my windows using the pressure washer as a
pump. It doesn't work with just a length of hose attached to the inlet.
However it does work with a �2.37 non return valve from toolsatan on the end.

Any thoughts why? I would've expected anything that might impede the flow, however slight, can only make matters worse.

I would've thought that increasing the height differential between the pressure washer and water supply would be all that's required.

Mathew

High pressure pumps work on a short/fast piston stroke; especially the
cheaper DIY machines. They aren't terribly good at self priming, which
needs a slower/longer piston stroke.

Cheaper machines need to be on the same level as the supply or below it,
few will suck more than 1 metre. The non return valve makes it a whole
lot easier.

--
Dave - The Medway Handyman www.medwayhandyman.co.uk

On 16/06/2014 17:59, The Medway Handyman wrote:
On 16/06/2014 16:21, Mathew Newton wrote:
On Monday, 16 June 2014 12:45:00 UTC+1, dennis@home wrote:
I wanted to use RO water to clean my windows using the pressure
washer as a
pump. It doesn't work with just a length of hose attached to the inlet.
However it does work with a �2.37 non return valve from toolsatan on
the end.

Any thoughts why? I would've expected anything that might impede the
flow, however slight, can only make matters worse.

I would've thought that increasing the height differential between the
pressure washer and water supply would be all that's required.

Mathew

High pressure pumps work on a short/fast piston stroke; especially the
cheaper DIY machines. They aren't terribly good at self priming, which
needs a slower/longer piston stroke.

Cheaper machines need to be on the same level as the supply or below it,
few will suck more than 1 metre. The non return valve makes it a whole
lot easier.

Exactly. Once you have pulled a little bit of water through the NRV it's
weight holds it shut against draining. Possibly worth priming the pipe
first. (A very useful tip BTW as I'll be wanting to do something like
this later in the year).

On Thursday, 19 June 2014 12:43:18 UTC+1, newshound wrote:

Exactly. Once you have pulled a little bit of water through the NRV it's
weight holds it shut against draining. Possibly worth priming the pipe first.

I think it's the attachment point/method to the water butt that's causing the issue. Sucking it out vertically will be beyond the ability of most cheap pressure washers and thus a NRV will be of potential benefit. However, attaching directly to the draw off tap will allow the water to be fed using the force of the head of water above it hence no NRV is required (and might even impede flow as mentioned).

Mathew

On 19/06/2014 15:25, Mathew Newton wrote:
On Thursday, 19 June 2014 12:43:18 UTC+1, newshound wrote:

Exactly. Once you have pulled a little bit of water through the NRV
it's weight holds it shut against draining. Possibly worth priming
the pipe first.

I think it's the attachment point/method to the water butt that's
causing the issue. Sucking it out vertically will be beyond the
ability of most cheap pressure washers and thus a NRV will be of
potential benefit.

Karcher state all their pressure washers can suck the stuff up, but only
with their special hose, with a NRV and filter.

However, attaching directly to the draw off tap
will allow the water to be fed using the force of the head of water
above it hence no NRV is required (and might even impede flow as
mentioned).

The flow rate for pressure washers isnt very high, they only use
something like 6-10 litres a minute.