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Pressure Washers Buyer's Guide

Looking for a pressure washer that can handle the jobs you need it to perform, but don't want to overspend for power you may not need? Our Pressure Washer Buyer's Guide can help you find the exact model that best suits your needs. Choose the best pressure washer for you from Industrial-, Heavy- and Medium-duty pressure washers for all types of applications, from stripping paint to washing windows.

Pressure Washers: What to Look For

Personal Use
Pressure washers for home use offer the benefit of cleaning better with less effort and in less time. The right combination of PSI (pounds per square inch), GPM (gallons per minute), nozzles, attachments and chemical cleaners let you wash siding and windows, clean walkways, driveways and patios, bring wood decks and fences back to life, power clean vehicles, boats, lawnmowers, ATVs, even cut back vegetation growing alongside driveways and walkways.

Consider purchasing a light-duty consumer, heavy-duty consumer or, professional model pressure washer for your personal needs.

Business Use
Pressure washers intended for business use will have greater pressure (PSI), water flow (GPM) and horse power (HP). Plus, you get extra features designed for greater performance necessary for heavy-duty cleaning in a shop, at a construction site or on a road crew. Depending on the model, these features could include a longer-lasting pump with adjustable pressure, easy-start engine, larger tank, wheel hose reels, hot water capability, longer hose and industrial-grade gun and wands. Northern understands the needs of the business user, and offers a great selection of professional and industrial pressure washers, in gas-powered or electric, cold or hot water models.

Horsepower (HP)
A higher horsepower engine is needed for higher PSI and higher GPM. The combination of PSI and GPM is what does the cleaning.

Pounds Per Square Inch (PSI)
A pressure washer's PSI rating is the maximum amount of force (pressure) discharged by the pressure washer. The higher the PSI, the more cleaning power available and the more things you will be able to clean. See chart below.

Pressure Washers
Application 1500 PSI 2600 PSI 3000 PSI 4000 PSI
Charcoal Grill x x x x
Bicycle x x x x
Automobile x x x x
Deck x x x
Wood Fence x x x
ATV x x x
Boat x x x
Siding x x x
Driveway x x x
Paint Surface Prep x x x
Semi Trailers x x
Farm Equipment x x
Construction Site x x
Paint Stripping x
Graffiti Removal x

Gallons Per Minute (GPM)
A pressure washer's GPM rating refers to the water flow during one minute of operation. The higher the GPM, the faster you will be able to clean. See chart below.

Cleaning Time* 2 GPM 2.5 GPM 3 GPM 3.5 GPM 4 GPM
20 min
18 min
16 min
14 min x
12 min
10 min x
8 min x
6 min x
4 min x
2 min
*Times shown are for comparison use only. Actual times will depend on operator skills and condition and size of job application.

Gas-Powered vs. Electric
Gas-powered pressure washers offer the portability necessary for outdoor work while providing higher pressures and flows for more industrial applications. However, gas pressure washers can only be used outdoors because the engines generate carbon monoxide.

Electric pressure washers must have safety features necessary when working near water, such as double insulation and a ground-fault circuit interrupter (GFCI). Though limited in overall power, electric pressure washers can be used indoors or outdoors and are quieter than gas-powered washers.

Hot or Cold Water Cleaning
Hot water pressure washers clean faster and more thoroughly than cold water pressure washers. They use less soap to sanitize and degrease, making them ideal for industrial and farm use. Cold water pressure washers are less complicated and are more compact for easy portability.

Pressure Washers: What You Can Clean (And More)

Pressure Washers: Frequently Asked Questions

When do I change the oil and what type of oil do I use?

  • First oil change: 15-20 hours or after 3 months, whichever comes first. Following oil changes should be every 200 hours or at least once a year. The oil should be changed, regardless of time, if it is milky-looking or the level is low. (The sight glass is on the side of the pump.) If the unit is being used frequently or commercially, you will want to change the oil more often. It is imperative that the oil is clean and water-free at all times.
  • Pumps use a 30-weight non-detergent pump oil. The use of motor oil will result in the oil becoming milky white in color. Units with gearboxes on the pump use 80W-90 gear lube oil. Do not confuse the gearbox with the actual pump when refilling or vice-versa.
  • Gasoline-powered pressure washers use an SAE 30W motor oil (10W-30) in the engine. Always consult the engine manual for specific instructions and be careful to put the correct oil in the correct place.

I'm not getting any pressure. What do I need to check?

  • Generally, all pressure washers 1,500 PSI or less use a push/pull type nozzle adjustment. Turning the nozzle sleeve adjusts the spray fan pattern. If the sleeve is pulled back, the unit is in low pressure. If the sleeve is pushed forward, the unit is in high pressure. A quick check of the nozzle holder to make sure the nozzle is in place will help as well. The nozzle looks like an Allen screw with a hole in the middle of it.
  • For 2000 PSI units and above, use quick-couple nozzles that can be exchanged with each other depending on the application. These nozzles are color-coded for easy use. Black - low pressure and soap injection. Red - 0 degree fan pattern (high pressure). Yellow - 15 degree (high pressure). Green - 25 degree (high pressure). White - 40 degree (high pressure).
  • The engine must be running at full speed for the pump to operate properly. If the engine is not running at full throttle, the pump will not be able to produce the proper flow of water to give the pump full pressure.
  • Sometimes the keyway may slip out from the engine shaft and pump sleeve. To check the keyway, remove the four bolts that hold the pump to the engine and slide the pump off. A quick visual inspection will verify if the key is in place.
  • After a certain amount of use and time the water seals may begin to leak. This is a normal occurrence as the seals are considered a wear item. A seal leak can be confirmed by looking between the pump and the manifold to see if water is dripping down. If so, it is time to replace the seals.

What size spray nozzle fits my pressure washer?

  • As a rule of thumb, the smaller the orifice size, the greater the restriction of water flowing through the machine causing the pressure to increase. Why is the proper nozzle size important? Nozzles too small can damage your equipment as water flow is limited potentially creating excessive load on the machine. Nozzles too large reduces operating pressure which reduces cleaning capability. Properly sized nozzles deliver maximum cleaning performance all the time. Use the chart below to select the properly sized nozzle for your pressure washer. Match your pressure washer's PSI rating (operating pressure) on the top to the GPM (gallons per minute) down the column to determine the proper orifice size on the left. If desired GPM falls between GPM listings, select the lesser GPM. Note, nozzle spray pattern size does not affect nozzle size selection.
    Step 1. Determine Your Preferred Broadcast Spray Pattern.

    Select your cleaning spray pattern from 0°, 15°, 25°, 40° or chemical. The size of orifice is stamped onto the connector nipple of the nozzle.

    Step 2. Match Your Pressure Washer's GPM + PSI to the Chart.

    Match your pressure washer's GPM (Gallons Per Minute—GPM) and PSI to the chart to determine the appropriate size. For example, the figures highlighted in red below reveal that in order to get 3.5 GPM @ 3000 psi, a 4.0 nozzle is required. If your desired GPM falls between GPM listings, select the lesser GPM.

    Orfice Size 1000 psi 1500 psi 2000 psi 2500 psi 3000 psi 3500 psi 4000 psi 4500 psi 5000 psi
    2.0 1.0 GPM 1.2 GPM 1.4 GPM 1.6 GPM 1.7 GPM 1.9 GPM 2.0 GPM 2.1 GPM 2.2 GPM
    2.5 1.3 GPM 1.6 GPM 1.8 GPM 2.0 GPM 2.2 GPM 2.3 GPM 2.5 GPM 2.7 GPM 2.8 GPM
    3.0 1.5 GPM 1.8 GPM 2.1 GPM 2.4 GPM 2.6 GPM 2.8 GPM 3.0 GPM 3.2 GPM 3.4 GPM
    3.5 1.8 GPM 2.2 GPM 2.5 GPM 2.8 GPM 3.1 GPM 3.3 GPM 3.5 GPM 3.7 GPM 3.9 GPM
    4.0 2.0 GPM 2.5 GPM 2.8 GPM 3.2 GPM 3.5 GPM* 3.7 GPM 4.0 GPM 4.2 GPM 4.5 GPM
    4.5 2.3 GPM 2.8 GPM 3.2 GPM 3.6 GPM 3.9 GPM 4.2 GPM 4.5 GPM 4.8 GPM 5.0 GPM
    5.0 2.5 GPM 3.1 GPM 3.5 GPM 4.0 GPM 4.3 GPM 4.7 GPM 5.0 GPM 5.3 GPM 5.6 GPM
    5.5 2.8 GPM 3.4 GPM 3.9 GPM 4.3 GPM 4.8 GPM 5.1 GPM 5.5 GPM 5.8 GPM 6.2 GPM
    6.0 3.0 GPM 3.7 GPM 4.2 GPM 4.7 GPM 5.2 GPM 5.6 GPM 6.0 GPM 6.4 GPM 6.7 GPM
    6.5 3.3 GPM 4.0 GPM 4.6 GPM 5.1 GPM 5.6 GPM 6.1 GPM 6.5 GPM 6.9 GPM 7.3 GPM
    7.0 3.5 GPM 4.3 GPM 4.9 GPM 5.6 GPM 6.1 GPM 6.5 GPM 7.0 GPM 7.4 GPM 7.8 GPM
    7.5 3.7 GPM 4.6 GPM 5.3 GPM 5.9 GPM 6.5 GPM 7.0 GPM 7.5 GPM 7.9 GPM 8.4 GPM

My engine will not start. What do I do?

  • Pumps without a pressure release need to have the trigger pulled while starting the engine. Make sure the throttle, gas and choke are all on. If all this checks out, inspect the air filter. If this is soaked with oil, replace the filter along with the spark plug. The last thing to check is the oil level. If the engine has a low-oil alert, just add more oil and the engine should start up. If all the above checks out and the engine will not start, contact a local service center.

I cannot get any soap injection. What should I do?

  1. Make sure the nozzle is correctly adjusted for low pressure. (Push/pull type or black quick-couple nozzle.)
  2. Make sure the soap injector metering valve is turned on.
  3. Make sure that the soap solution is the consistency of water.
  4. Make sure that the low-pressure tip is not clogged.

If the above steps are followed to no avail, remove the high-pressure hose and run the pump/engine with the soap injector turned on to see if it works without the hose. If it does, replace the hose, gun, wand, nozzle and tip, in that order, to determine which item is defective.

It is starting to get cold. How do I winterize my pressure washer?
Prepare the pressure washer for storage by running RV anti-freeze into the unit. This will keep the internal parts lubricated, protected from rust, and prevents the pump from freezing. Please use environmentally friendly RV anti-freeze whenever possible using the following procedure:

  1. Connect a short piece of garden hose (2-3 feet long) to the water inlet fitting of the pump. Use a funnel to pour the RV anti-freeze solution down the hose.
  2. Disconnect the high-pressure hose from the pump, if it is still on the pump. Drain it and store it in a warm, safe place.
  3. Pour the RV anti-freeze solution down the funnel and into the short hose. Start the machine and let it draw the solution through the pump. This can take up to 2 minutes. Shut the pressure washer down when the solution begins to spray from the pump outlet.
  4. The machine is now ready for storage. Simply flush it out with clean water when you are ready to begin using it in the spring.

Note: This procedure works best if you have someone to help with the hose and funnel.

Or you can purchase environmentally-friendly Northstar Pressure Washer Pump Freeze Guard, 12 oz bottle specially formulated to protect your pressure washer from freezing & corrosion. Easy to use 12 oz bottle screws onto the pressure washer, while contents gets sucked into the pump.

My unloader is stuck open. How do I clean it out?

  1. Unscrew the large red cap above the manifold.
  2. Remove the spring and washer that were under the cap.
  3. Unscrew the large brass bolt from the manifold and pull it out.
  4. Clean out the unloader valve in warm, soapy water and inspect for any debris or metal burrs. Remove any foreign materials.
  5. Flush out the cavity the unloader was in by running garden hose water through the pump. Use a flashlight to inspect the cavity for any debris and clean it out.
  6. Reassemble the unloader, taking care not to strip the brass threads. Make sure the red knob is screwed down tightly (hand-tightened).

Still need help?
Email our product experts, or Call 1-800-221-0516 our 24-hour sales line.