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Gary I beg to differ. 4gpm would be the max size when relying on house output. This is what we use and sometimes its a problem. Especially in older homes that may have older galvanized pipes which tend to swell closed and restrict water flow from the house. Its not too much for watering plants AS LONG AS your using at least a #10 tip (1510). It actually breaks the water up better to give an even hydro blast. Sometimes we'll even downstream a little Miracle Grow for good measure.

$500.00 is fair as long as its in decent shape.

We'll get close to 7-9 in the mountains cuz they crank it up in those parts. In the older areas it can be quite weak. If your getting that high gpm's consider yourself lucky.

Def. get the 4 GPM, if you wind up using it with a surface cleaner ever, the extra flow will make all the difference in the world!

Roof Cleaning Grand Rapids Michigan 616-914-9064 wrote:

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Looking to buy a pressure washer just to have on the trailer for those houses that have terrible water pressue for watering plants. I found one in my area, it's built by H&R industries, 13hp honda, comet pump, 4 gpm, 3500psi. Low hours. He is asking 500.  It is on a stainless cart.  No hoses, wands or tips.  Good price, yes or no ?

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 Yes if it is a commercial grade Honda engine - norm $800 engine alone.  If houses in your area put out at least 5gpm the pump will not cavitate.

 

Municipal water pressure can fluctuate given the time of day. It’s most noticeable on weekends.

I have a 50gal tank that I just throw on the truck with a cold water machine when I need to do a job that doesn’t require heat. It’s a great buffer tank. I made a whip that connects to a standard male hose fitting and QC’s to the inlet side of my portable water filter. This probably goes without saying, but you’d be amazed at garbage the filter pulls out of the water.

Baltimore MD Roof Cleaning 410-482-4367 wrote:

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We let the pumps cavitate on the small units, with well water all around us it's almost unavoidable. We only run the 4gpm if the 8.5gpm is already in use and we want a second washer on site. The 50gal tank is a good idea. We have 2-electric pumps on board and can run the second one for rinse water if need be with our large enough 90hr battery. We are rinsing more and more houses with our 8.5gpm unit and it's almost as amazing as when we started cleaning roofs with SH. So fast we added 300-400 per day in the same hours.

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 More water flow is the way to go.  I carry a 200 gallon water tank on my trailer for that purpose.  A house faucet can not support a 8.5 gpm pump let alone 2 of them at the same time.  More water flow allows the house wash to be applied and rinsed faster and more thorough.  We always turn the hose water off before we are finished so we do not have to carry any water in the tank when we travel.

What is the horsepower of the engines for your pressure washers?

Most people use 13HP engines.  I see that yours only puts out 3200 PSI so 9 if it is less than 1300 HP you would have to upgrade the engine to a 13HP.

So assuming that I would take the 13HP engine and attach a hard gear drive box.  To that I would attach a GP (or your favorite) 8.5 gpm bump.  With a small diameter tip it can put out 3600 PSI.  If you use it with a surface cleaner for cleaning concrete you will no longer have to worry about leaving the surface cleaner in one spot for to long on fresh concrete (under 4 years).  That can leave circles in the concrete if you use a 13HP 4000PSI/4GPM pressure washer.