Generally, cold water pressure washing combined with the right chemicals will be sufficient and work quite well for most paint professionals in most situations. My company happens to own and operate both hot and cold units, but we use the cold water washers most of the time, only bringing out the heat when necessary.
Hot water IS better and more effective, but in most situations it just isn’t necessary. It would be like bringing a much larger paint sprayer than needed when a small one would do. That said, chemicals do work better at warmer temperatures, and the cleaning process can go twice as fast. Dirt, grease and other contaminants loosen and clean better and deeper with hot water. Think of it like your laundry, dishes, or even your own body. Some cold water and soap will do the job. But hot water is more effective.
Hot water washing can also extend your washing season. There are times when ambient or surface temperatures are too cold for cold water washing, and a hot water unit can be used to offset those conditions. It also can open new opportunities for cleaning things such as graffiti, gas stations, dumpster pads, hood cleaning, etc. Some people use hot water washers to clear ice dams from roofs or gutters if their units can make steam. They can also be used for cleaning tractor trailers, de-icing weigh stations on highways when they get plowed in, or even clean agricultural equipment.
It is a pricier game to get into, though, as an 8 gpm/3,500 psi unit costs about $4K. And adding a hot box or a hot water skid can run another $2-$6K.
So, for my company, we only run the hot water units when necessary. That decision is usually made based on either temperature or the type of stains we are trying to remove. Chemicals don’t work as well under 50 degrees, so that is where we make the call based on temps. It also helps to keep the crew’s hands warm when working in colder temps!
Christian Militello - Militello Painting & Powerwashing - Ambler, PA.