Actually, water volume is as important as psi in determining the cleaning power of a pressure washer. Cold--water units will generally require more water and pressure to achieve the same results as a hot-water machine.
More to maintain
Cold-water pressure washers are fairly simple; an engine powers a pump which propels presssurized water through a small opening. Hot-water units are a bit more complex. “Water enters a pressure washer from a spigot or tank via a garden hose. It first passes through a high-pressure pump, which speeds water on its way through a heating coil, consisting of up to 200 feet of half-inch, schedule 80, steel pipe or tubing,” explains Price. “The helical or circular winding configuration allows the water to get maximum exposure to the flame (fueled by diesel oil or natural gas/propane) as it roars through the center of the coil. By the time the water rushes out of the coil and through the wand and nozzle, it will have reached temperatures of up to 200F degrees.”
Lembezeder suggests, “Depending on your water source, it is recommended that you delime your coil on a regular basis. When winterizing your hot-water washer, it is important to protect your unit by either running compressed air into the system to remove all of the water or running a mixture of antifreeze solution through the system.”
He notes that with hot--water units, it’s also necessary to winterize the coil using one of the above procedures.
“Other maintenance issues with a hot--water washer such as burner air adjustment, testing water and fuel pressure, testing water temperature, inspecting burner fuel pump internal filter and replacing the fuel nozzle should be done by an authorized technician,” Lembezeder says.
According to Joyce Lequesne, service manager at Ben’s Rent-All in Las Vegas, hot-water pressure washers might require more maintenance than a cold-water unit, but they still aren’t what she would consider “high-maintenance” rental items. In fact, Ben’s Rent-All stocks an equal amount of hot- and cold-water machines. The hot-water units come in especially handy with the amount of restaurant business in the Las Vegas area.
“Hot-water pressure washers are one of our better rentals,” she says.
Additional controls and features found on hot-water units do add to the maintenance concerns, however, says Price. “Major manufacturers now offer field and factory training schools to rental operators who want to have their mechanics up to date on both hot- and cold-water washers. This is growing in popularity because many rental centers are actively marketing new equipment, as the profit margins are excellent at the retail level. The aftermarket for repair parts, accessories and detergents is very good.”
In the end, the decision of whether or not to add hot-water pressure washers to your fleet is one dependent upon your customers’ needs and your ability to justify the expense and additional maintenance. There is no doubt about their effectiveness and versatility in the war against dirt.
Hot water--Dirt’s #1 enemy
According to information supplied by Shark Pressure Washers, there are three key elements in the successful removal of dirt and grime - heat, agitation and soap.
Heat-Creates a high-speed molecular action that causes the cleaning agent to be more active and reduces water’s surface tension so it can effectively penetrate grime at the molecular level.
Agitation- Describes the impact that comes from the water volume and water pressure hitting the surface, similar to the action of your hand scrubbing a dinner plate in your kitchen sink.
Soap- Chemically breaks the bond between dirt and surface. Detergents use softening agents, technically referred to as surfactants (an abbreviation for “surface reactive reagents”) to emulsify the oil and grease. Once the oil and water are able to mix, forming an emulsion, the dirt--still clinging to the oil and grease-- can be carried away in the wash water.
“If you’re cleaning engines, automotive parts, or anything with oil and grease, you’ll need hot water,” says Keith Price, vice president of sales for Shark Pressure Washers. “Like the dishes in your sink, hot water melts away grease and grime; cold water only pushes it around.