GPM psi opinions please

So before I buy a pump what's your thoughts?
Starting with cold water only. Residential stucco, roof tile, pool cages and flat work will be my target work until I can buy and add heater .
I believe pool cages will be plentyful so a 200ft hose and a extra 100 ft will be needed.

Now would you go with 3500psi 8gpm or 3000psi 10 GPM?
Second question will running roof wash chemical through my high pressure hose destroy it for softwash applications, before I add a clear braid hose?

dont use washer hose for roofs.

8 or 10 GPM? Do you have any experience at all?

Like buying a hyabusa for a first motorcycle.

Experienced in pressure washing yes but not as a business. Never owned more than a 4 GPM PW.

My first bike was a fzr 600 but an h2 hummer killed my zx10r in 2005 and almost me. Getting run over jokes are funny.

flanbo said:

Experienced in pressure washing yes but not as a business. Never owned more than a 4 GPM PW.

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IMO I think 8 or 10 is a bit over kill for you. But either way, if your business fails you won't have any trouble selling either one of them here

Nobody wants to buy used 4 or 5 GPM machines that much.

The expenses for a unit with less capabilities price point is pretty close. I'd hate to turn down flat work because I couldn't compete. If I had to choose between residential vs commercial, commercial would be my preferred choice. Also I'm more of a night person and finding a partime employee to work 2-3 nights will be cost effective especially during the hot rainy summers.
Before moving to Florida I did work for collages, schools, water treatment and utility companies installing security gates, fencing, smaller concrete pads. Before 2003 mostly residential remodeling so I'm a carpenter at heart and by trade.
I prefer working and selling to property managers than home owners. Fuel stations, restaurants, store fronts I will market to mostly.
On the other hand some cheaper marketing and leg work around town may be great and pay the bills for 2 years. 2 years is my goal for a second 2 man crew truck, trailer and revolving service contracts.

So what's everyone thinking or opinions about GPM psi delema I'm having? 3500psi 8gpm or 3000psi 10gpm???
What really has me is there a big difference in cleaning power in hose length say 150 ft to 300 ft?

If i remember correctly, maybe someone will chime in if I'm incorrect, 8 GPM is the max that you can get out of 3/8 hose, anything over requires 1/2". Friction loss will reduce the PSI at the nozzle.

8 GPM running through 3/8" hose will loose about 300 PSI for every 100 ft. So 3500 PSI, 8 GPM running through 300 feet of 3/8 hose would give you appx. 2600 PSI @ 8 GPM = 20800 Cleaning Units

8 GPM running through 1/2" hose will loose about 80 PSI for every 100 ft. Again 3500 PSI, 8 GPM using 300 feet of 1/2 hose would give you appx. 3260 PSI @ 8 GPM = 26080 Cleaning Units

10 GPM through 1/2 hose will loose about 120 PSI for every 100 ft. So 3000 PSI, 10 GPM using 300 feet of 1/2" hose would give you appx. 2640 PSI @ 10 GPM = 26400 Cleaning Units

It really depends on what size of hose you want to work with and how much pressure you need at the end of the hose to get the job done. Of coarse there are other variables that factor in with how well the system will perform.


Edit: Now that I think about it, volume would probably be reduced at lengths over 100 ft or so, especially if you were at the max flow rate of the hose size already. And the numbers I used above assume the entire 300 ft length was unreeled and laid out straight. Friction loss would be much higher if only 50 ft of hose was unreeled, for example.

If you're planning on doing commercial and gas stations you should add hot water into the mix. The minimum Should be 5.5 @ 3500. 8 gpm @3500 would be a whole lot better.

Perfect.
Any thoughts about liquid cooled engines? Found a 28hp Kawasaki at a great price.
Great information, exactly the help I needed. Thank you so much.

I would take volume over pressure. I think air cooled is better in these small engines. Landscapers love those kawasakis, I think that is a good engine.

Once you get past 25 hp I would feel liquid cooled would start being a better choice then air cooled. I have a 35 hp air cooled briggs that has been wonderful for me, but if I did it again I would go liquid. Liquid takes more room, and has more parts that can go wrong. They do run cooler, makes a bigger difference in warm climates as well.

My vote is 8 at 3600 especially if you are doing concrete because if you use longer runs of hose the psi will drop a little an once you pretreat the concrete you still need some psi with that volume to take care of it.Also if the concrete has low areas that extra water will be a pain to deal with.

Think im going to jump on the liquid cooled Kawasaki 28 hp kawasaki . It stays about 92 degrees everyday June to mid September and humid as hell 80% I'd think..the LqC Maybe General has a pump to split the difference 9gpm @ 3350 psi.
I'm from nj, every negotiation ends with Well I got " CASH " now you split the difference..
Was telling the roof wash guys I got my first the second estimate while at the barber today. 1 from the barber and another guy getting his hair cut.. Think it was a lucky day but my barber up north referred me to quite a few small jobs. Tip your barber good guys.

Thanks everyone for taking the time to help out. Joe

LOL have not seen a barber in 20 years. As far as the " cash " I do not discount myself or my company, we accept cash checks or major credit cards. I do know some lower there price for cash but is that an over bid or a cut to yourself.

I here you on the cash discount. It happened all the time in Jersey. Always happened on the final payment. Guys always pulled out a 2 inch knot of cash, then the " I Got Cash " quote . , " How Much For Cashshsh? You always want to say sure dash is great and add 10% since your ur doing so well. And through in that gold chain also. Now tuck in your chest hair it looks like an ascot.