There are many options to power washing. Its actually very easy to power wash without causing damage with the proper knowledge.
You must consider hot water or cold water, the degree of fan pattern, specialty nozzles, orifice of the tip, PSI, GPM, cleaning chemicals and of course the application of the water to the surface being cleaned. In this article we will be covering all of these topics.
The Details Of Power Washing Safely
What Is The Difference Between PSI and GPM?
PSI is Pressure per Square Inch. GPM is Gallons Per Minute. These two usually run together on the power washers that you will find in most stores. PSI is what blasts the grime off the surface and GPM is what rinses the grime away. Most go by a formula of Cleaning Units = GPM X PSI. My larger cold water unit is a 4.0 GPM at 4000 PSI, That would be 16000 Cleaning Units. This would not be correct when figuring Cleaning Units for a hot water unit. The bottom line of it is that 1500 PSI will clean just about anything except cement, especially with the correct cleaning chemicals. Professionals will usually prefer GPM to be higher because this allows for more Cleaning Units without the PSI that can dig into surfaces and cause irreversible damage. However as I said, power washers usually run hand in hand with PSI and GPM. Read our Post about where we tell you which pump actually put out what they say they do.
Specialty Nozzles For Power Washers
There are a ton of nozzles and gadgets for Power Washers. Floor Cleaners and Power Nozzles work on the same concept of a zero degree tip which focuses all of the PSI on one spot. Some Floor Cleaners have few of these tips that all rotate very fast and the Power Nozzles will only have one nozzle that spins very fast. However we would NEVER suggest the use of these products. They are simply crutches for a system without the necessarily cleaning units. The zero degree tips often can cause damage to many surfaces including cement. It is always better to use a powerful but safe cleaner to speed up the process than a tool that can cause damage.
Tips For Power Washers
Tips come in a few degrees: 0,15,25,40. This is simple.
- Use the Zero to clean only an areas that you can’t reach with a ladder easily (about 15 to 20 feet away from the tip).
- Use the 15 degree to clean cement or other durable surfaces.
- Use the 25 degree to clean wood or other surfaces that can be damaged but still need a good amount of cleaning.
- The 40 degree is only really useful to rinse or to clean your car safely.
Power Washer Tips Have Different Orifice Size.
Less inexpensive pressure washer models have a pressure actuated unloader valve. This mean that you can get a tip with a larger orifice to let more water out and lower the pressure. If you try to get a smaller orifice size to increase the pressure it will actuate the unloader valve and shut down the system and cause extreme wear and tear. That is generally only be possible with a flow actuated unloader valve which is much more expensive and not ever on the lower priced units. Below is a link to a chart that will help.
Power Washing Chemicals
Power Washing Chemicals can be costly. For specialty needs Krud Kutter makes a great line up of cleaners. The other cleaners that and powerful and cheap are bleach and TSP. TSP can be bought at any Menards or even some smaller stores. Never use the phosphate free version. Its like putting a governor on your sports car. TSP is Tri Sodium Phosphate and is VERY effective and cheap. It will clean anything that you will be repainting or is not a painted surface. Bleach can be used to kill mildew and mold. Bleach also will brighten your deck or fence prior to staining. TSP and Bleach can safely be mixed together to make a very effective but yet very inexpensive cleaner. It will also burn the crap out of your eyes so always wear goggles when power washing with TSP and/or Bleach.
Next Please Read Our How To Stain A Fence article for more information on properly power washing.