Karcher suction hose.

[dennis]

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.

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.

[Mathew Newton]

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 pres sure washer and water supply would be all that's required.

Mathew

[The Medway Handyman]

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.

[newshound]

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).

[Mathew Newton]

I think it's the attachment point/method to the water butt that's causing t he issue. Sucking it out vertically will be beyond the ability of most chea p pressure washers and thus a NRV will be of potential benefit. However, at taching directly to the draw off tap will allow the water to be fed using t he force of the head of water above it hence no NRV is required (and might even impede flow as mentioned).

Mathew

[dennis]

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

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