Mating two pressure washers.

[PLD 14]

For those who have wondered what would happen if you plumbed two pressure washers together... It works fine. At least with two pressure unloaders. I plumbed together a 4gpm and a 5.5gpm machine into 1 bad a** machine putting out ~8gpm. Total cost, 88c for a 3/8" tee and three QC's I had laying around. The results:

- Need two hands to hold the gun.

- Rinses concrete like a firehose.

- No increase in distance with a #9 & #13 xjet, but creates ALOT larger mist/fog cone.

[Atlantic Power Washing 14]

Make sure you are using at least a number 10 nozzle. If you're using the number 4's, then one of the unlouders might not come out of bypass. One thing I would suggest; buy you an unlouder like the 2140 green spring, they have two inlets and are rated at 21 gpm, and tie both machines into that one unlouder....

[Larry B 55]

Do you have pic of the setup? Are they just plumbed together after the unloaders? I thought about doing this for concrete work.

[VanDiesel99 14]

They both have to be rated for the same PSI right?

[PLD 14]

Yes, they are just plumbed together after the unloaders. Actually, "plumbed" is a little more permanent that what I did. I took a 3/8" galv T and put in to female and one male 3/8 QC's. A whip from each unloader feeds the union, and the union feeds the hose.

I have presssure unloaders, so this info may not apply to a flow type unloader. When not in use, the pressure rises above 3500psi and both unloaders bypass. When using a tip that is too small, the pressure rises above 3500psi and the unloaders unload some of the volume until the line pressure matches the set spring rate. This is exactly what happens when you use a proper size tip and use the knob on your unloader to lower the pressure.

As for being rated the same, it is a good idea that they be really close. I you mate a 2500 and a 3500, the smaller pump will likely be in bypass constantly (yielding no volume gain). Also, the smaller pumps internal check valves will be holding back 3500psi which may be beyond their design spec. You could use a gauge and dial down the larger unit to the smaller units psi specs. Then, the "big" unloader would bypass any water above 2500psi. You wouldn't get full volume, but you would get more than each seperately.

As for Tom's thoughts about a #4 tip, it is partially correct. In an incompressible system, line pressure is line pressure is line pressure. Each unloader will open or close, relative to it's own threshold pressure. If the line pressure is greater than the unloader's pressure, it will open. A #4 tip would result in both unloaders being partially open.

[PLD 14]

One important note: When doing this, the unloaders may be in various states of bypass during normal water flow. Because of this, it is imperiative that your unloader bypass into a tank of sufficient capacity or spoil the water to the ground. DO NOT plumb two pressure washers together if your unloader bypass is plumbed back into the pumps H2O inlet port or the bypass line inaccessible like the combo unloaders/pump head found on consumer pressure washers. If you do, you will likely cook your pump seals and never know why.

[Econoclean 14]

What about linking them together on the opposite side of the unloader valve, or before the unloaders. Then Bolck the outlet of one machine and connect the wand to the other machine. So the unloader with the lower settings will automatically do the Job. Of course you must make sure the unloader that is set on the lower pressure can handle the flow. There would be no need for adjusting the Unloader valves. You would only need to change the nozzle. If the unloader set to the lower pressure can not handle all the flow you would have to adjust both Unloaders to the same pressure and then this whole setup would not have much benefit. What do you think about this Idea?