Mobile Pressure Washing Setup

[Jayhawk_Aviator]

I have a Simpson 3700 psi, 2.5 GPM gas pressure washer. I have a 70 gallon poly water tank (like what you find at Tractor Supply) and I'd like to make a small mobile pressure washing setup. Ive heard some say you can just use gravity from the tank to the washer, but I called Simpson and they advised against it. I asked them the question I have and they were no help.

My question is this. What type of pump would be recommended to boost the outlet from the tank to the inlet of the pressure washer (which is normally a hose)? Ive heard people say to use a submersible pump w/ hose outlet and drop it in the tank, but that runs continuously and it seems like that would burn up the pump if you weren't pulling the trigger on the washer. Quick google search wasn't helpful.

Im sure someone has done this and can offer advice or recommendations on pump or setup in general?

Thanks,
Scott

 

[Youngandfree]

Are you doing mobile car detailing? I would use a 12v demand pump with a gpm higher than the 2.5gpm pressure washer.

You're going to burn up your pressure washer if you aren't pulling the trigger for more than 30-60 seconds.

 

[Jayhawk_Aviator]

Thanks

No detailing, just want to be able to pressure wash where there is no water. I’m looking for a solution that doesn’t burn I up the pump if the trigger isn’t pulled.

 

[no704]

No help on that, but a friend had a similar setup and had a couple softner tanks in the rig.

 

[Jswain]

You could install a Y in the pump outlet, one going to the pressure washer and one returning back to the tank.

May have to add a valve on the one to the tank to pinch it off some unless you use a pump with significant head

 

[Youngandfree]

Thanks

No detailing, just want to be able to pressure wash where there is no water. I’m looking for a solution that doesn’t burn I up the pump if the trigger isn’t pulled.

Then you need a completely different machine that you can setup a bypass on. Water still flows continuously through it, but when not on the trigger, it circulates through the bypass. Your baby homeowner machine isn't made to do that. Even when your machine is connected to a hose bib with pressure, if you stay off the trigger very long, the pump is toast. So having a pump to feed it from a tank is one issue, but that won't allow you to stay off the trigger long.

Nevermind a 70g tank won't last very long if you have no water source.

My brother has a pressure washing biz.

 

[Youngandfree]

You could install a Y in the pump outlet, one going to the pressure washer and one returning back to the tank.

May have to add a valve on the one to the tank to pinch it off some unless you use a pump with significant head

The pump needed to be able to have a bypass built in. Usually opposite side of the pumpbfrom the water inlet us a cap that you remove and install the bypass hose back to the tank.

 

[cliffcharb]

I've never used a pump to feed the inlet in any of my pw setups. Most pumps only require flooded inlet pressure.
I built a couple mobile detail trailers and elevated the tank which allowed the user to use all of the water available in the tank. (plus always kept the inlet line full)

 

[mikegt4]

I use the same setup for my pressure washer at my rural property. For years I had been using an old sump pump to pump water out of the pond and into the PW, it supplied enough water pressure and flow for the PW pump intake. If I was working on something too far away from the pond I would fill 3-4 garbage cans in the bed of my pickup with water then use the sump pump to transfer it to the PW. Between getting tired of that process and the fact that with this summer's low rainfall causing the pond to nearly dry out I picked up a 275 gal. tote to bring water from my daughter's house if I need to use the PW. This week I used the tote for the first time and I parked my pickup truck on ground about 6' higher (plus the height of the truck bed) than where the PW was and it seemed to work fine. If I didn't have a significant height difference available I would have run the tote outlet into a garbage can using it as a surge tank and use the sump pump to transfer water to the PW. My PW is a fairly small unit, 2500 psi/2 gal. minute so it may require less water input than a larger more powerful unit.

A couple of years ago I replaced my PW's pump when it wore out (internal plastic parts crumbled from age) after 25 years of occasional use, IIRC the new pump instructions said that the pump needs something like 7-10 psi minimum input pressure to avoid internal damage.

 

[Jayhawk_Aviator]

Any reason I couldn’t just plumb in a pump at the tank outlet then install a bypass valve https://www.tractorsupply.com/tsc/p...Z3FSTx2-wrpAs0Bx_6bepOAXcs_FGJ3xoCDj4QAvD_BwEto circulate back to the tank if Im not pulling the trigger for long periods and the pressure builds up too much? This is an occasional use thing (1-2 times per year) and it feels likes there should be a simple solution.

 

[Youngandfree]

Any reason I couldn’t just plumb in a pump at the tank outlet then install a bypass valve https://www.tractorsupply.com/tsc/p...Z3FSTx2-wrpAs0Bx_6bepOAXcs_FGJ3xoCDj4QAvD_BwEto circulate back to the tank if Im not pulling the trigger for long periods and the pressure builds up too much? This is an occasional use thing (1-2 times per year) and it feels likes there should be a simple solution.

Nope. Not what that is designed for. Your actual pump on the pressure washer needs to have a built in bypass. Buy a different pressure washer.

 

[Jswain]

Nope. Not what that is designed for. Your actual pump on the pressure washer needs to have a built in bypass. Buy a different pressure washer.

He's worried about the feed pump burning out, not the pressure washer pump.

Clearly it works as is when fed by a garden hose, he is simply trying to feed the pressure washer with a pump instead of the water pump in his home.

There is a very simple solution, buy a pump and make a loop so it circulates the tank & tie into that with a Y or T to feed the pressure washer. Or mount the water tank higher then the pressure washer and gravity feed

The pressure washer doesn't know whether its getting water fed from a garden hose at 40psi (or whatever you get for pressure) or your new water pump

 

[Youngandfree]

He's worried about the feed pump burning out, not the pressure washer pump.

Clearly it works as is when fed by a garden hose, he is simply trying to feed the pressure washer with a pump instead of the water pump in his home.

There is a very simple solution, buy a pump and make a loop so it circulates the tank & tie into that with a Y or T to feed the pressure washer. Or mount the water tank higher then the pressure washer and gravity feed

The pressure washer doesn't know whether its getting water fed from a garden hose at 40psi (or whatever you get for pressure) or your new water pumping k

I know what he's worried about. The problem is he is still going to burn up the pressure washer pump staying off the trigger. Doesn't matter how he is feeding it. Garden hose connected to a hose bib with 100psi and 10gpm, he's still burning up the pressure washer pump staying off the trigger with it running.

 

[Jswain]

I know what he's worried about. The problem is he is still going to burn up the pressure washer pump staying off the trigger. Doesn't matter how he is feeding it. Garden hose connected to a hose bib with 100psi and 10gpm, he's still burning up the pressure washer pump staying off the trigger with it running.

If he uses it the same way as he uses it while it's plugged into a garden hose then the pressure washer pump will last as long as it would either way.

 

[Sumboodie]

70 gals won't last long.

 

[PoorUB]

70 gals won't last long.

28 minutes of continuous use. Probably one hour of real time.

 

[Youngandfree]

If he uses it the same way as he uses it while it's plugged into a garden hose then the pressure washer pump will last as long as it would either way.

Looks like he hasn't been using it much based on his own words.

Thanks

No detailing, just want to be able to pressure wash where there is no water. I’m looking for a solution that doesn’t burn I up the pump if the trigger isn’t pulled.

 

[Jayhawk_Aviator]

Jswain has it right. Pressure washer works just fine when plugged in to the hose at the house. Working just great (and as designed) for 10 or more years. Not sure I follow the comment about burning up the pressure washer pump when connected to the hose bib.

I’m just trying to mimic the output of the house hose in a mobile environment. I use it all the time at the house, but wish to use it 1 or 2 times a year mobile. If I mimic the flow and pressure of the house, the pressure washer doesn’t know the difference where the water is coming from. Can easily mimic the flow and pressure with a pump at the water tank outlet, but don’t know how to do it without burning up said pump.

 

[Bert_]

A submersible pump will stay cool a lot longer than your power washer pump with no flow.

If you leave it running with the trigger off your power washer will burn up long before a submersible pump.

So when you shut your power washer off just shut the submersible pump off at the same time. Keep it simple.

 

[cliffcharb]

Jswain has it right. Pressure washer works just fine when plugged in to the hose at the house. Working just great (and as designed) for 10 or more years. Not sure I follow the comment about burning up the pressure washer pump when connected to the hose bib.

I’m just trying to mimic the output of the house hose in a mobile environment. I use it all the time at the house, but wish to use it 1 or 2 times a year mobile. If I mimic the flow and pressure of the house, the pressure washer doesn’t know the difference where the water is coming from. Can easily mimic the flow and pressure with a pump at the water tank outlet, but don’t know how to do it without burning up said pump.

I think you’re looking for something like this?
We use these for our job site pump setups.
We deliver 275g totes and use a well pump to supply water to job trailers. The tank is simply supplied by flooded water pressure from the tank. This pressure switch will cut off power in case the tank runs out.

Square-D Pressure Switch 30/50 with Low Pressure Shut-off

The industry standard for controlling electrically driven water pumps. Low Pressure Shut-Off operates at approximately 10 PSIG below cut-in and will turn off the pump. Square-D 30/50 Pressure Switch with Low Pressure Shut-off.

aquascience.net

 

[Youngandfree]

Jswain has it right. Pressure washer works just fine when plugged in to the hose at the house. Working just great (and as designed) for 10 or more years. Not sure I follow the comment about burning up the pressure washer pump when connected to the hose bib.

I’m just trying to mimic the output of the house hose in a mobile environment. I use it all the time at the house, but wish to use it 1 or 2 times a year mobile. If I mimic the flow and pressure of the house, the pressure washer doesn’t know the difference where the water is coming from. Can easily mimic the flow and pressure with a pump at the water tank outlet, but don’t know how to do it without burning up said pump.

Then why did you say this?

Thanks

No detailing, just want to be able to pressure wash where there is no water. I’m looking for a solution that doesn’t burn I up the pump if the trigger isn’t pulled.

That's referring to the pressure washer pump. No matter how you feed the pressure washer, not pulling the trigger for any length of time will burn up the pressure washer pump. nevermind 70 gallons is so little it's not going to clean much.

 

[Dozerhand]

You guys are overthinking this. This is all you need to supply a pressure washer from a tank.

 

[goodwrench]

belt drive and gear drive pumps turn slower and therefore draw water. some direct drive pumps will work with slight positive pressure. as long as the bottom of the tank is level or higher than pump inlet. i have run a small 2.5 gpm comet direct drive pump off a tank. the biggest factor is a big short supply hose from tank to pressure washer with no air leaks. i used a 3/4 id hose with 3/4 cam locks from tank to inlet. try it and see what happens. if it doesnt prime up and work correctly, stop. also start it with no tip and trigger pulled so pump can prime with no resistance. get a short piece of the biggest hose, atleast 3/4 id, stiff enough it won’t collapse, raise the tank up some. also the tank will work differently full vs half vs empty due to gravity and pressure at tank outlet. with the hose hooked to the tank, water should flow freely when held at the height of pressure washer inlet, i believe it is referred to as flooded inlet, the pump can’t **** the water but if it has slight positive pressure it may work . you have the tank and pressure washer won’t take much to try gravity feed and see what might work for you. if one way doesn’t work try something different.

 

[Jayhawk_Aviator]

Dozerhand, that looks like the right solution. On demand pump with a built in pressure switch. Thanks for sharing.

 

[MileHighRover]

Then why did you say this?


That's referring to the pressure washer pump. No matter how you feed the pressure washer, not pulling the trigger for any length of time will burn up the pressure washer pump. nevermind 70 gallons is so little it's not going to clean much.

No, he was referring to the pump he would put in the 70 gallon tank. YOU misunderstood the OP.

99.9% of gas powered homeowner pressure washers come with a bypass and a thermal relief valve. He's not burning up the pump that easy.

 

[Dig Doug]

Raise the tank up off the deck and gravity feed the PW from the bottom or bottom edge of the water source.

this shouldn’t be a problem w/ a 1 inch line to the PW, or do 2 -1 inch lines to the PW - If your worried make it an 1.5 / 2 inch line PVC hard piped to the PW

if you don’t have a bung port, an RV repair shop or a Mobil RV guy can heat a couple bungs in the bottom edge of the tank, That will solve any lift issues with a pump.

also an RV 12 volt water pump would also work - once it reaches pressure it shuts off

just don’t over think the project.

a regular trash can submerged pump would work add a T in the discharge line to the PW and run a line back into the tank just make that line slightly undersized - you’ll need a power source to power the pump. Milwaukee makes a transfer pump that uses M18 batteries

i would go gravity feed very simple less moving parts

 

[Youngandfree]

No, he was referring to the pump he would put in the 70 gallon tank. YOU misunderstood the OP.

99.9% of gas powered homeowner pressure washers come with a bypass and a thermal relief valve. He's not burning up the pump that easy.

Mkay. They are so reliable that's why they sell cheap replacement pumps.

 

[Youngandfree]

Dozerhand, that looks like the right solution. On demand pump with a built in pressure switch. Thanks for sharing.

Funny the very first response said use a 12v demand pump.

 

[Dmm698]

Run box store Ryobi I think its 2.5 GPM or something and 3k PSI at the motocross track all the time just gravity fed off a 55 gallon plastic drum. Not a problem. Stick your thumb over the pressure washer side of the hose and dunk the other end of the hose down into the bottom of the tank , remove thumb, connect to washer. Or you can just dump the barrel on its side and allow gravity to force water out down the hose.

My expensive Mi-T-M 2GPM 1800 PSI or so Hot power washer actually is a gravity feed by design. Its got a hopper box with a float, and this is a commercial unit.

The only time i've ever used a transfer pump for something like this is to move water from a drum into my camper. I wouldnt reccommend it for a pressure washer because its going to be basically dead headed when you arent on the trigger on the wand.

 

[metlmunchr]

Use a centrifugal pump rather than a positive displacement one and you'd have no need for any bypass or recirculating loop. For example, this 12V pump from HF https://www.harborfreight.com/12v-dc-transfer-pump-290-gph-63324.html at zero flow will produce 17 psi and it would just sit there and run holding that pressure if the flow is blocked. Not only will the pump or its motor not burn up, but the motor load will actually be less than it is at zero back pressure and the full 290 gph flow rate. That's the nature of centrifugal pumps and how they operate.

 

[Galaxywide]

Use a centrifugal pump rather than a positive displacement one and you'd have no need for any bypass or recirculating loop. For example, this 12V pump from HF https://www.harborfreight.com/12v-dc-transfer-pump-290-gph-63324.html at zero flow will produce 17 psi and it would just sit there and run holding that pressure if the flow is blocked. Not only will the pump or its motor not burn up, but the motor load will actually be less than it is at zero back pressure and the full 290 gph flow rate. That's the nature of centrifugal pumps and how they operate.

That HF pump is not a centrifugal pump, it uses a positive displacement rubber impeller (that seems prone to failure, according to reviews). The dead giveaways are self priming and the shape of the pump housing - neither are features of most (all?) centrifugal pumps.

 

[metlmunchr]

That HF pump is not a centrifugal pump, it uses a positive displacement rubber impeller (that seems prone to failure, according to reviews. The dead giveaways are self priming and the shape of the pump housing - neither are features of most (all?) centrifugal pumps.

You're correct. I only looked at the pumping characteristics which are similar to a centrifugal pump in that the design of the impeller limits the maximum head. I'd call it a semi positive displacement as opposed to a true positive displacement such as a gerotor pump or piston pump which either moves liquid or locks up when the pressure exceeds the available horsepower.

That said, a pump of this design should do what the OP wants without the need for any bypass circuit or valving. As far as the durability of the impeller is concerned, I suspect more than a few users with problems have run the pump dry. The water pump on an outboard motor is of the same design and will run fine for a hundred hours or more pumping water, or it will run dry for about 30 seconds before the impeller dies. I look at HF reviews and figure if there's 15% or less of one and two star reviews then the product is likely pretty good if used properly, because a general cross section of HF customers includes way more than 15% who never read directions, abuse most everything they touch, and expect anything they buy to be indestructable. Not saying they don't put out some defective products, because they do. But they also have more than their share of defective customers in my estimation.

 

[Ing3018]

I have a Simpson 3700 psi, 2.5 GPM gas pressure washer. I have a 70 gallon poly water tank (like what you find at Tractor Supply) and I'd like to make a small mobile pressure washing setup.....

I gravity fed my pressure washer pump when I washed my mother-in-law's house siding a few months ago. I didn't trust her hose bib to deliver consistent flow so I made a buffer tank from a Rubbermaid garbage can. I used a 1" bulkhead fitting through the wall at the bottom of my "tank" and left the tank in my trailer so it was elevated a bit. The pressure washer was stationed nearby on the ground. I made a short hose (8') from the bulkhead to the inlet of my pressure washer and fed the pressure washer inlet through an inline screen filter. The short hose is clear and I watched to verify that it did not collapse or cavitate in the pump.
I free-flowed a garden hose into the top of the tank through a float valve that was designed for filling livestock water troughs. This shut the flow off from the hose when the tank filled. It actually worked really well. If I was continuously on the pressure washer trigger (4 gpm Cat pump), the draw of water from the tank would slightly outpace the flow from the hose / valve. I think the fill valve is a bit restrictive.
I am aware of being "on the trigger" frequently to minimize risk of overheating the water in the little bypass loop at the pump unloader. I would rig up a bypass to the buffer tank if this was something I planned to do more often.
I did this to protect my pump from starvation rather than wanting to be mobile with my water supply, but the basic idea is the same as what you want to do, I think.