what water pump do I need for my electric 1800psi 1.6gpm PW?

[sahrcar]

I am starting up a mobile auto detailing business and am trying to figure out how to constantly get enough water pressure into my pressure washer to use properly. My current setup is a 125 gal tank inside a minivan. The tank has a lid on top which can be screwed on or off and also down at the base there is a regular faucet type attachment I added on as well. My pressure washer is a Briggs and Stratton 1800psi with 1.6GPM. I went to Lowes and Northern Tool and ended up buying a Wayne pc2 115v 2 amp transfer pump which claims it can pump out 340 gal/hr. It worked for the first car wash I did but now that Ive let it sit for 1.5 months with little use its not working at all for me and is just producing a light mist out of the pw. I called the stores and then the manufacturer. There is a more powerful unit available thats $90 more than the one I originally got and it puts out 1450 gal/hr but the guy from Wayne said that that wouldnt work for me either. He said once I stopped squeezing the pw wand the water would just stop and then the pump would stop as well..? I thought the water pump would just keep pumping water into the pressure washer continuosly?



So before I go out and waste my money by buying a more powerful water pump what kind of pump do I really need to get the water out of my water tank and into my pressure washer? Gravity feed isnt working and my pw is light enough that I take it out of the vehicle and place it onto the ground each time. Water tank is about 3-3.5ft tall and is level on the van floor. I can feed from the top or feed from the faucet near bottom. Thanks for any advice and suggestions yall can provide me!

[neighborsenvy]

I may be wrong, but what I have read you need more gpm`s. Ive used an electric before and it was only somewhat decent for wheels. It was way underrated for anything else.

[sahrcar]

It works fine when I can connect directly to a faucet attached to a house. I dont have the money right now to purchase a more powerful gas pressure washer. I guess I`ll have to stop advertising my washes as luxury foam bathes and instead just say delicate paint cleansings so that way I can do an ONR wash when I cant hookup to a water source directly.

[sahrcar]

Just spoke with the pw manufacturer. They said they can`t reccomend hooking up an electric pw of any kind up to a water tank since there might not be enough psi coming into the pw and water might run out. they said I need at least 20 psi constantly to operate. The more powerful pump I`m looking at puts out 50psi. Its constantly pumping so that should allow me to wash a car on the go right? Or should I just save my $180 and try to find a used bulky gas pw ?

[the other pc]

First off, if your pressure washer flows 1.6 gpm (which is 96 gph) and the mfg says you need at least 20 psi, you`d theoretically need a pump that produces at least that.



But since you said the Wayne PC2 worked fine the first time you tried it, it seems that the pressure washer doesn’t really need 20 psi. (But that might be marginal so don`t bet the farm on it.)



Wayne`s spec sheet (http://waynepumps.com/index.cfm/product/12_4/pc2.cfm) shows that at 100 gph the PC2 is good for less than 30 ft of head (that`s pump speak for 13 psi).



The Wayne guy was right when told you the pump wouldn’t work because the water stopped flowing when you release the wand trigger. You don’t see any water coming out anywhere do you? That means it ain’t flowin’, at least not from the input to the output and certainly not through the transfer pump.



Water pumps like the one you have aren’t designed to pump into a blocked line (called “dead head” operation). They normally pump from an open container to another open container.



Dead heading a positive displacement pump like a piston, lobe, screw or gear pump will severely stress it. You probably broke the pump, or at least blew out a seal.



Pressure washer pumps have pressure relief valves that allow the pump to keep operating into a shut off line. The relief valve circulates water from the output back to the input of the pump so it never sees a dead head.



You could do the same for your transfer pump by adding a relief valve and a line running back to the reservoir.



Let’s say your pressure washer really does need 20 psi at 96 gph. And let’s you have a pump that’s happy to put out 20 psi at 96 gph and 30 psi at 50 gph.



So, with a relief valve set at 30 psi and a line running back to the reservoir, when you pull the trigger in the wand you get 96 gph of water at 20 psi to the pressure washer. And when you release the trigger, flow to the washer stops, pressure shoots up, the relief valve opens at 30 psi and 50 gph of water flows back to the reservoir.



If your transfer pump has enough excess capacity, you won’t even need a relief valve. You can do it with just a constriction in the return line.



Let’s say your transfer pump puts out 106 gph at 20 psi and 20 gph at 50 psi. With the wand on you get 20 psi with 96 gph to the washer and 10 gph to the return line.



With the wand off you get 50 psi, 0 gph to the washer and 20 gph to the return line.



The constriction can be as simple as a narrow tube or a plug with a hole drilled through it but it’s easiest to set up if you use an adjustable valve. Whatever you do, never turn it off. You’ll just break another pump.





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