Hey, all. Was hoping to get some guidance on our new setup. My 18y/o son is in his second summer of pressure washing driveways in our community (Northwest MS). He just upgraded from a Simpson Pro with 200cc Honda/2.5gpm AAA pump to a BE 14hp Kohler Command with General EZ4040G pump rated at 4,400 psi / 4 gpm. We bought it as a lightly used demo from a local BE dealer, and he gave us a good deal on a new BE 20” Whirlaway surface cleaner to go with it.
We cleaned our sidewalk first with the new setup, and got some striping. The BE surface cleaner came with 2502 nozzles. Bought a pressure gauge, and with unloader backed off one full turn from full, was pushing 3,800psi at the pump.
Bought new 25025 tips and installed today. Pressure at the pump dropped to 2,600psi (which I’ve read is more appropriate for residential concrete). But when we let off the trigger, pressure jumps up to around 3,400psi (way more than the 300-500 psi I’ve read it should go up between off and on). We’ve cleaned another section of sidewalk, and no more striping, but I’m concerned about the pressure differential with the new tips.
The external unloader is a VRT3 unit.
I appreciate any guidance, as I don’t want to turn him loose with defective equipment, or worse yet, ruining someone’s property. I’ve watched more YouTube videos on adjusting unloaders than I’d care to admit.
Thanks!
-RB
On residential jobs, 2,500 PSI is more than enough for just about anything he will run into. Setting the unloader to 3,000 PSI gives you some headroom but more importantly it while reduce system stress, wear, and pressure spikes. When you release the trigger, there’s always a split-second delay before the unloader switches to bypass, and during that time, pressure spikes toward the unloader’s set point. The higher that set point, the more potential spike range you create. So if you’re working at 2,500 PSI with the unloader set to 3,800, the system can spike up to 1,300 PSI. If you set the unloader to 3,000, the spike potential drops to just 500 PSI, resulting in a milder, quicker transition and smoother operation overall.
Ok - makes sense. Given the setup we have, is a 600-800 psi pressure spike OK when using the surface cleaner, or are we risking equipment failure?
I haven’t tried the wand with 25* tip yet, but if I leave the unloader untouched, shouldn’t the pressure be higher compared to the surface cleaner with two nozzles?
Thx!
Since it’s adding more undue stress to the unloader every time you let go of the trigger, it will impact the longevity of all parts involved.
I’m assuming when you say 25* you are talking about the degree of fan, what orifice is it? To set your unloader to 3000-3250 psi you would need a 4.5 tip.
Is it normal to have to adjust the unloader when switching between surface cleaner and wand? Due to differing pressure needs.
No, that’s what the nozzles do. Set the unloaded using the correct nozzle to the MAX you want the unloaded to reach and never touch it again… then use nozzle orifice size to adjust the psi lower.
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