Hot water pressure washers are a wonderful source of hot, convenient, inexpensive hot water and pressure. Turn on the unit; hit the burner switch, and SHAZAAM! In just the time it takes to run the cold water out of the hose assembly, you have instant hot water available for cleaning your equipment, floors, or fleets. The advantages of the hot water pressure washer make it a common tool for many facilities. It becomes an integral part of your operation and everyone depends on its reliability to be ready to operate at a moment’s notice.
How many times have you turned on the unit, fired it up and either experience loss of pressure or no heat. It affects your operation and generally involves expensive repairs. That is the bad news. The good news is you can train your people to properly use the pressure washer and dramatically reduce the need for costly downtime and repairs.
Heat is your friend and heat is your enemy! The hot water produces much quicker cleaning results and is a must when dealing with oils and greases. The heat left unchecked can also destroy the very equipment you rely on. Here is how you can prevent unnecessary downtime and repairs.
RULE #1- NEVER USE A SUPPLY SOURCE OF WATER IN EXCESS OF 120° F TO YOUR PRESSURE WASHER.-THIS TEMPERATURE WILL DESTROY THE SEALS AND CHECK VALVES
All hot water pressure washers regardless of brand or model pressurize the water before sending it to the burner for heating. All pressure washer pumps are designed to pump cold or slightly heated incoming water. The pump seals have very strict limitations of heat. Typical pump manufacturer’s ratings of internal pump parts are a maximum temperature of 140° Fahrenheit. Some manufacturer’s prodice a high temperature seal set that is rated to 170° F.
RULE #2-NEVER ALLOW A PRESSURE WASHER TO RUN FOR MORE THAN TWO MINUTES WITH THE TRIGGER GUN CLOSED. THIS WILL OVERHEAT PUMP RESULTING IN EXPENSIVE PUMP REPAIR OR PUMP FAILURE
The second source of heat is in the pump itself. All pressure washer pumps are designed to produce a rated pressure (PSI or Barr) and a rated flow (GPM). This is a constant unadjustable flow and pressure. When the trigger gun is closed to stop the flow, the pump is still attempting to produce the rated flow and pressure. The mechanism for relieving that pressure is a pressure relief valve commonly known as an unloader. The unloader is factory set to open a bypass line once the pressure in the pump elevates by about 10-15%. This triggers opening of a bypass in the unloader and the pressurized water is redirected to the low pressure side of the pump. This allows the pump to continue to operate at rated flow and pressure until the trigger gun is opened. The unloader valve is closed with a set spring force to return water to the trigger gun. Here is the problem; the total volume of water being recirculated is less than a half gallon. As that water bypasses from high pressure to low pressure it creates frictional heat. It is meant to be only a temporary closure of the trigger gun. If the unit is left in bypass for an extended period of time, that bypass water can reach levels in excess of boiling point. At that point the pump seals and oils seals are destroyed, the check valves are destroyed, the ceramic piston sleeves are in danger of cracking, and chances are the bypass hose will fail as well as it is subjected to heat well beyond its rating. It is vital that your unit not be allowed to run in bypass for periods longer than 2-3 minutes. You can protect against this failure by training employees to shut down the unit immediately upon completion of the work. You can add a time delay shut down to shut if off after a timed sequence of a closed trigger gun, or you can direct the bypass to a drain or tank. Don’t run to the lunch truck until you have properly shut down the unit.
RULE #3-NEVER SHUT DOWN HOT WATER PRESSURE WASHER WITHOUT PROPERLY COOLING DOWN THE HEATING COIL. THIS WILL OVERHEAT AND DAMAGE PUMP COMPONENTS, HOSES, AND O-RINGS
The third form of heat comes from the burner itself. Pressurized water is sent from the pump to the heating coil. Water travels through a coiled steel pipe as the burner is producing heat and sending heat through the center of the coil. As the water exits the heating coil, a thermostat monitors the outgoing temperature and cycles the burner as required to maintain the set temperature. Typically heated water will reach a maximum temperature of 160 to 190° F. This constant temperature will be maintained based on the consistent flow of water from the pump. Once the burner is shut off, the flow of cold water to the heating coil serves to cool down the coil to ambient temperature. It will generally take 2-3 minutes of running the unit to cool down the coil. A good rule of thumb is to run the unit with burner off until the wand is cool to touch. This insures the coil is cool before the unit is shut down.
A common theme with high failure rate pressure washers is the operators are shutting down the unit without proper cooling. The potential for failure is very high. Remember, the coil is red hot during burn conditions. If allowed to shut down without cooling, you have the heat of the coil itself heating the water remaining in the coil. This water can easily reach temperatures exceeding 200° F. As this water heats, it is thermally transferred through the water directly to the pump. This elevated temperature in the pump will lead to damaged seals, leaking seals, and eventually loss of pressure and leaking pump. If the oil seals are impacted, water can enter the crankcase and lead to catastrophic pump failure. In addition, hot water left in the high pressure hose, bypass hose, and trigger gun can lead to softening of the hoses and o-rings and will dramatically reduce the life of the hoses, quick connects, and trigger guns. Insuring longevity and reliability of your hot water pressure washer is as easy as cooling down the unit before shutting it off. Every time!!!
Following these three simple steps will add thousands of hours of use to your investment. It will potentially eliminate thousands in avoided repairs. Most importantly, it will reduce downtime associated with improper use of your equipment. Keep your equipment ready for use with these simple practices.