Pressure Washing Frequently Asked Questions


FAQ's (Frequently Asked Questions) will help you understand some of the basic concepts of pressure washing systems. This list will help both new users as well as those that need to brush up on their current knowledge about pressure washers.

What is power washing?
Power washing, or pressure washing, is the growing application of high pressure water spray. Produced by specially designed pumps, this spray is a hundred times more powerful than the typical garden hose. On concrete it is used to remove unsightly mold, bubble gum, and other dirt stains. Wooden decks are returned to the look of new wood, void of graying and fatigued finishes. And on houses, the appearance of siding (namely aluminum and vinyl) is greatly improved by removing pollution, mildew, and other signs of neglect.

Nozzle Usage:

0º - red nozzle: Narrow and powerful stream of water. Used for very difficult to remove stains, caked mud, tough dirt.
15º – yellow nozzle: Uses a small angle of spray for focused cleaning. Good for somewhat difficult to remove dirt.
25º – green nozzle: Uses a medium angle of spray for washing sensitive and soft surfaces (deck, fence, aluminum etc.)
40º – white nozzle: Largest angle of spray used for cleaning surfaces quickly and for rinsing.
65º – soap (black) nozzle: Soap tip is used in conjunction with the cleaning fluid. This is the only nozzle that can be used with cleaning solutions.

Choose the correct size spray nozzle.

What chemicals can be used?
Use only cleaning solutions that are power washer approved. On our pressure-washer-chemicals page you will find sufficient solutions that are safe for your machine, plus they are biodegradable and environmentally friendly.

Why can't chemical injection be used under high pressure?
Applying chemicals in low pressure has two advantages. First, if the chemicals were applied in high pressure, they will splash off, resulting in wasted solution. Secondly, because chemical injection only works in low pressure, you can change from low pressure to high pressure at the wand, instead of going back to the unit to engage chemical injection.

What is the chemical injection to water ratio?
The ratio that the chemical is diluted varies slightly from unit to unit. The most common ratios fall between 12:1 and 18:1.

frequently asked questions

Can I use bleach in my pressure washer?
NO! You must NOT use any household bleach with your machine. By using them you will damage the seals and o-rings in the gun, wand, hoses and pumps.

Can I use hot water with my pressure washer?
NO! Hot water can cause damage to the o-rings and pump. Once water reaches 145°F, the thermal relief will activate. Note: some of our units have 160º F and 180º F max temperature pumps (see our Hot Water Pressure Washers).

Can I use water from a lake?
NO! Water that is drawn from a lake may contain debris that will cause the pump not to perform correctly. Also, it will shorten the life of the pump since they are not designed to draw water from a stationary source.

What kind of oil should I add to the pump?
See your owner's manual for the exact type of oil.

What if my engine doesn't start?
Check out our list of Troubleshooting Tips or refer to your Manual.

How long can hoses be extended?
The recommended length is 100 feet. The unit will operate at lengths beyond this, but performance will somewhat decrease, and chemical injection may not operate satisfactorily. Go to our hose extension pressure loss page to find out the exact amount of pressure being lost with hose extension.

Why should I keep my nozzles clean?
Clogged nozzles can increase pump pressure and possibly damage the pump. Immediate attention is required.

How do I clean clogged nozzles?
1. Always disconnect your spray wand from the gun before cleaning your nozzles!
2. Clear the nozzle with a small rigid piece of wire such as a paper clip.
3. Flush the nozzle backwards with water.
4. Reconnect the wand to the gun
5. Restart the pressure washer and depress the trigger on the spray gun.
If the nozzle is still plugged or partially plugged, repeat number 1-4.

If the previous procedure does not clear the nozzle, replace with a new nozzle.

When should I drain the gasoline from the engine?
You should always remove the gasoline from the engine if you plan to store the unit in your basement or transport it in a vehicle. You should never store combustible materials in your home.

How do I add the anti-freeze and water solution?
If you must store your pressure washer in a location where the temperature is below 32°F, you can minimize the chance of damage to your machine by utilizing the following procedure:

1. Shut off the water supply and relieve pressure in the spray gun by depressing the trigger.
2. Disconnect the garden hose from the pressure washer, but the leave the high-pressure hose connected.
3. Tip the unit on its side with the inlet connection pointing up.
4. Insert a small funnel (to prevent spilling) into the inlet and pour in a 50/50 solution of antifreeze* and water.
5. Disconnect spark plug wire.
6. Without connecting the garden hose, pull the recoil several times to circulate the antifreeze in the pump system.
7. Continue to add antifreeze and pull the recoil until the antifreeze is expelled when the trigger is pulled.
8. Turn the unit upright.

Where is the best place to store my pressure washer?
Store your pressure washer in a clean, dry place that is well ventilated away from open flames or sparks. If you plan to store your pressure washer in a shed or unheated garage, be sure to winterize before the first frost. If you plan to store it in a basement, you should remove all gasoline from the engine.

Why does water come out of my pump?
If you run your engine for several minutes without spraying the wand, the pump will automatically purge water to protect it from overheating.
This is called the automatic cool-down or thermal relief system.

Is pounds per square inch (PSI) or gallons per minute (GPM) more important?
Both. The PSI delivers the "punch" to a washing application, or in other words, forces the contaminant off the surface. The GPM will flush the contaminants. Most homeowners and pressure washer contractors will opt for more PSI while the farmer and agriculture needs the flow to push contaminants to the final destination.

Can I get a 2000-PSI or larger pressure washer that operates on 110-120 volts?
Power requirements (voltage and amperage) are determined by motor size. The highest rating that can be operated on normal 110-120 volt electrical circuits is 2 GPM/1400 PSI which uses a 2 HP motor.

I do not understand the electrical power supply requirements on your different models. Please explain.
Each model has a "standard" voltage and phase listed in the specifications for that model. However, other power ratings are optionally available on all models. The standard electrical ratings are:

110 – 120 volts
208 volts/1 phase
230 volts/1 phase
230 volts/3 phase
460 volts/3 phase
Contact Ultimate Washer Application Department at 866.858.4982 for information concerning non-standard power ratings.

If this frequently asked questions list did not completely answer your questions, please refer to some of the other help pages.

Airplane Washing | Boat Washing | House Washing | Industrial-Agricultural  | Garage Washing
Gas Station Washing
| Gutter Washing | Fence Pressure washing | Deck Pressure washing | Roof Power washing