I am considered the purchase of a pressure washer. I can't seem to find the
answers to these questions. The specifications usually state a maximum
pressure and flow rate. What if my well pump doesn't provide at least the
stated flow rate? Will the pressure washer fail to operate properly? Also
I assume that the pressure can be dialed back to any number less than the
stated maximum. Is this correct? I'd hate to buy one and wish I'd gotten a
higher pressure unit.
TIA for your help.
I always wondered about the well question. I guess it would depend on how
long you use the machine. Every well has some storage capacity for the times
you need a high draw rate (washing machine filling etc). Eventually you will
run the well out if you draw more than its flow rate. Pressure washers don't
like to run dry and the pumps can be damaged if run dry.
You don't really dial in the pressure. It is controlled by the tip size you
use. Smaller tip greater psi.
Hope this helps
We have a small homelite gas powered pressure washer. We're also on a well
(relatively high flow rate - we use it for an inground irrigation system).
The washer has an inlet pressure sensor to check the water pressure on the
_inlet_ to the pump. If the inlet pressure falls below 25 PSI, the unit
assumes that the water supply cannot keep up, and it shuts off the motor (shorts
out the spark I think) to prevent damage to the pump (high RPM pump needs
water flow for cooling).
When we first obtained the unit I'd hook it up, pull-start the motor and it
would run fine _until_ I pulled the trigger. At which point the inlet
pressure would drop near/below 25PSI, and the motor would quit (or cough a lot
as the pressure oscilated, depending on how hard I pulled on the trigger).
At the best of times if I pulled the trigger "fast", it'd quit and need
restarting. If I pulled it gently, it'd hesitate and then eventually run
I fudged around with the pressure sensors on the well pump to increase the
"engage" pressure higher (it was originally between 25 PSI and 30 PSI).
Now, as long as the hose supplying the pressure washer is relatively short
(and/or the larger 3/4" hose), and don't place other simultaneous demands
on the well pump, it runs perfectly without coughing or hesitation.
I believe the well pump is now set to somewhere around 35 PSI for
"engage". Shut off is around 45-50PSI.
Upon occasion, it still won't cooperate (ie: very long supply hose).
In those cases, I reach inside the unit and disconnect the pressure
sensor wire (spade lug) making sure that the free end won't contact
anything. But this means I have to be _very_ careful that the water
supply is turned full on at all times the pressure pump is running.
Otherwise, the pump will self-destruct fairly quickly.
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
info. on some of your other questions. I have a gas pressure washer
(Karcher) rated for 2700 psi, has a 7 hp rated engine.
I do have a pressure adjuster- by turning this knob it changes the pressure.
It is necessary to dial down to a real low pressure to put on chemicals-
mine has a chemical dispenser for things like siding cleaner, deck cleaners,
car wash suds, etc.....
As mentioned in other responses, changing the tip also changes the
pressure. You can also vary the pressure on the surface you are cleaning by
backing away with the wand. My owners manual strongly recommends a 3/4"
hose to bring water to the unit. Even with city water there are times when
the washer kinda "cuts out" for a second or two, then goes back to full
blast. Maybe has to do with overall water consumption at the house.
Doesn't seem to harm anything, though, since some water is always running
thru the pump.
I try and avoid using the pressure washer when anyone in the house is using
a lot of water, like if the wash machine is being used, or the dishwasher,
or our irrigation system is running, etc.....
I'd think that there would be reasonable safeguards built into the unit to
prevent pump failure in the event the water pressure supplying the washer
drops. After all, even someone on city water can't always be sure that
pressure will always be as needed. Running the pump dry may not be good,
but unless your water supply totall stops, there should be some water
reaching the pump at all times. Then again, maybe that's not the case on
well pumped water. Can you actually outstrip the well pumps supply rate?
Once you make up your mind on what size washer you want, maybe rent one
similar to test it on your water supply.
I have a pressure washer that I bought from Northern about 10 years ago.
It initially performed very poorly because my well couldn't supply
it with sufficient water. After drilling another well with much more
flow it performs admirably. Having to "baby" it so as to not empty the
pressure tank was a real pain.
The pressure can be adjusted. Most pressure washers have a valve that
shunts water from the output of the pump back to the input when the
pressure gets above a selected value. The range of adjustment isn't
from zero to infinity but it will allow you to control the output
pressure by a factor of 2 or 3.
I don't know what your application is but bear in mind that bigger isn't
always better. I rarely run above 1,000 to 1,500 psi. When cleaning
off wood siding or decks more force than that pressure yields will
seriously erode soft woods like cedar. Car washing at 1,500 psi is
fine, but you still need a brush.
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