Newby PW build

Hi guys, I’m completely new to this trade and am really struggling to figure out a few things so please be patient and expect dumb questions.

I’ve currently got a 450cc 14hp Hyundai engine sitting in its box and am about to order a 20lpm 3600psi interpump but I’m a little concerned/confused about the pressure it will be producing. Firstly, will the 3600psi generally be enough for most typical jobs? Or would I be better off finding something with a bit more mmph behind it? I’ve always thought the PSI depends on the tip you use given that you have enough flow? Also would you guys recommend using a 16” surface cleaner or higher?

I apologise for these very basic questions and fully understand you must get these on the daily but I’m really struggling to find any information / opinions on anything. Local firms around my area (Kent, UK) tend to be too defensive about helping out.

Kind regards,


Generally speaking you will never need more than 2500psi at the nozzle for washing houses or concrete. Gallons (liters) per minute is much more important.

A 16" surface cleaner is a good size for a ~5gpm pump you have.

Make sure whatever unloader you get is ‘fully plumbed’ so you can use a small buffer tank instead of hooking directly up to a ‘hose pipe’ as they call it there.

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Thank you for the reply dcbrock, would it be man enough to to fully function a 16” surface cleaner. The work I’m doing will be predominantly ground work

2500 psi/5.5gpm pump will work fine for ground work. 2500/8gpm is a lot better but you’d need a bigger motor.

Mildly curious, aren’t they severely restricting water use in the UK? I keep getting news articles about ‘hose pipe’ restrictions.

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So you’re saying get a higher GPM pump than the one I’m looking at? Does pump in question not cut the mustard im a little lost here

Thanks for the replies, just seen the full messages you were sending they weren’t fully showing for some reason. Seem to be getting heatwave after heatwave here so unfortunately do have hosepipe bans at the moment. Luckily the rig won’t be ready until next month but I can imagine how frustrating it is for others

It’ll do ok, 5.2gpm here in the US is considered a ‘transitional’ pump size until we get an 8gpm. I honestly don’t know how things work in the UK so the other guys can comment better than myself.

You’ll be fine with 14hp and 20lpm getting started. 16 inch surface cleaner will work. Don’t lose too much sleep over it, some on here are using dewalts and make it work.

Newbie here also - I’m using 15lpm as my starter and it works well - I’ve had no issues doing straightforward flat work, plus I like that it’s a simple, portable setup where I don’t have to attach a buffer tank whilst I’m learning my work flow.

I’m sure once I step up to 30lpm (8gpm) it will make a huge difference to the speed and also expand the type of jobs I can do.

The way I see it at the moment I’m still learning and my inefficiencies are not at my machine.