Pressure Washer, advice needed!

Phantom

Phantom

Phantom

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Joined
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Southampton, Hampshire
Having had the unfortunate pleasure of washing my car on the weekend due to the serious lack of water pressure of the hose ive decided to invest in a pressure washer.

"aaaah you'll strip the paint off the car!!1" i hear you cry but as long as its set to a low bar it should be safe... plus its a new car and there arent any rust spots to flake off anyway!

right, from all my searching and knowledge gathering ive decided to go for a low power, induction motor (it'll be quiet too, so no need for ear protectors!) and one that can pump out enough water to do a cleaning job justice.

something i dont understand is how is a pressure washer able to generate the pressure if there is low pressure in the first place? incoming is slower than the outgoing therefore wouldnt it just run out of water to pump though? im guessing there has to be some sort of large resevoir in order to compensate?

the one i have my eye on is the Karcher 499M. Does anyone own one of these? Opinions? :)
 
that one should be fine as long as you dont use the dirtblaster attachment

my dad has the K399 and it was so good my m8 bought one :D really is a quality peice of kit and does a great job mixing the water and cleaner together especially with the spinny brush bit

i would imagine the washer would just suck the water from the hose, its only hydrostatic pressure that makes the water come out of the hose normally anyway
 
Phantom said:
something i dont understand is how is a pressure washer able to generate the pressure if there is low pressure in the first place? incoming is slower than the outgoing therefore wouldnt it just run out of water to pump though? im guessing there has to be some sort of large resevoir in order to compensate?
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Flow rate and pressure are different (but connected) things.

For a given (volume) flow rate through a nozzle you can increase pressure by reducing the nozzle size - or in simple terms, squashing the end of a hosepipe makes the water come out faster.
 
kaiowas said:
Flow rate and pressure are different (but connected) things.

For a given (volume) flow rate through a nozzle you can increase pressure by reducing the nozzle size - or in simple terms, squashing the end of a hosepipe makes the water come out faster.
Click to expand...


yes but... when the flow rate is a trickle, theres only so much pressure you can generate from it, before closing off the end (i.e. becomes too small) right?
 
For car washing, you want a higher flow rate over bigger peak pressure as you want to get lots of water onto the car.

Karcher washers are about the best you can buy for domestic use. Shop around though because the prices vary dramatically - I bought a K6.85M a couple of months back and got it for £230 from the jungle place that sells books and electrical goods. Lots of places were asking £300+.
 
i'll never forget the time when i used a pressure washer on the 205gti, i went over a small stone chip and ripped a piece of paint off about the size of a 1p coin LOL

just be VERY carefull with them :D
 
the cheapest ive found the K499 M above is £129.97... i dont really want to pay a lot as the most it'll be used for is washing cars and maybe the patio. can they be used with say a sand blaster attachment?
 
chopchop said:
just be VERY carefull with them :D
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A good few yeas ago, I used to fix pressure washers. We had one machine that was rated at 200+bar and ran off a 3 phase motor (415V) and was the most powerful pump we had.

We were testing it and hadn't bothered to fit an unloader valve (valve that either cuts the motor or allows the water to circulate in the pump head) My boss was on the gun and another guy had is head over the pump.

The boss forgot about the valve, let go of the gun and the brass pump caps fired past the guys head actually catching his hair, went through the skylight in the ceiling and we eventually found 2 of the caps in the car park!

Impact would have probably have killed him - So yes, be careful :)
 
Phantom said:
yes but... when the flow rate is a trickle, theres only so much pressure you can generate from it, before closing off the end (i.e. becomes too small) right?
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But a pressure washer dosn't increase pressure just by having a small nozzle, if that were the case it wouldn't need a motor. The pump inside is what make it capable of generating higher pressure than the hose pipe that feeds it, the actual flow rate of water into and out of the pressure washer is exactly the same unless it has a leak.

The the source of the water is so restricted that it cannot supply the demands of the pressure washer, then obviously it won't work.
 
Just after christmas I managed to pick up a Halfords HP200 at half price - bloody bargain tbh and when the soap mixing thing working too it cleans very well :>

Back up to full price right now though so maybe look lower down the range? :)
 
I'm tempted to pick up one of the lower spec Karchers from Macro - £39.99 + VAT. Should do the job and i'd rather have a bottom of the range Karcher as opposed to a mid range cheepie brand.
 
panthro said:
do pressure washers actually damage the car paint?
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IMHO, I would say its simply a matter of how close in inches you want to play russian roulette with the nozzle.

And I'm speaking from recent experience... I took a slice out my cars paint not two weeks ago... just getting the nozzle that 'little' bit closer to get that 'little' bit of dirt off :o

In future I'm going to draw a 2 foot chalk circle around the car and not let the nozzle anywhere inside it!

(It's great for the alloys though...)
 
About 10 years ago I had a Karcher which got heavy use (until I lent it to a mate and never saw it again). Last year I thought I'd get a new one and while wandering around B&Q I saw one of their own brand ones for £30, bagain I thought!.

I got it home, cleaned my driveway with it and put it away. That was the only time it ever worked. The stupid thing just conked out and never worked again.

Then a few months ago I got another Karcher. Moral of the story is if you buy cheap you'll probably buy again. Definitely get a good brand like the Karcher if you can.
 
We use a Lavor petrol powered one, £100 from Makro.

The pump went on the first one, but they replaced it, and in all honesty we've never ever had a pressure washer that didn't give up the ghost, we use them a lot what with the bikes and so on.

It's nice though not having an extra cable to fanny around with!
 
be very careful as regards the water pressure. when i closed my unit i bought my clarke hot/cold p/w back to use at home. it has a water tank fitted so i figured it would be ok on our low pressure.not a chance...oncethe tank is empty,it actually starts to stall and spit. and if the wife turns a tap on ..forget it. :eek:
 
1. if the paint is ood a pressure washer is fine, if their are nicks or sticker edges stay clear with the pressure washer..

2. If the hose flow is a trickle, the pressure waher will run dry every few seconds and kill the pump by running it dry...

pressure washers need a good supply or they die quite quickly...

:(
 
I got a nice karcher for XMas.

I have used it with just water so far and it works well. I have to go and buy some cleaning fluid ideally.

I have found I still need to sponge the car down though as it doesnt remove dirt as such.

It is the best thing in the world for cleaning alloys though.

When I did my Dad's A6 alloys we couldnt believe how good they came up!
 
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