Walking through the power washer section of a big box store is a lesson in things that don't matter. All of the products are listed by PSI, while PSI is a factor in cleaning ability it is far from the main criteria. 

Generally power washers are listed by two criteria, PSI and GPM. PSI stands for pounds per square inch and GPM stands for gallons per minute.

Gallons per minute is higher on this list than PSI, the volume of water that is used to clean will allow you to clean much more surface. PSI will only allow you to clean that small amount of surface really deep. 

So you are probalby asking what the key is to high speed, high quality cleaning.

Heat. 

Think about it, when you wash dishes you don't use cold water? You scrub the grime and grease off of that pan with a stream of hot water to help. Concrete works the same way. Contaminants that are stuck to the surface have bonds that need to be broken, the best way to break these bonds is heat.

The ideal system for you depends on how much concrete you are planning to clean. PSI never needs to exceed 4000psi for any type of concrete cleaning. GPM should be above 3 for decent work speed. Now for the defining factor...heat.

Some manufactures claim that their machines can generate 230-240 degree water. Sorry, water outside of a pressure vessel can't go over 212 degres. Otherwise it will flash to steam and reduce your cleaning ability. We use a water temp of about 200 degrees, we have found it is able to break the bonds on the surface but does not flash to steam. 

If you have any questions about pressure cleaning I would be more than happy to help you. Also if you feel your job is too big to tackle yourself we would be happy to come out and help. You might find our prices can beat your cost of doing in-house cleaning! 

www.devilwash.com

-Zach