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Answer: A bypass wand means it has a ball valve mounted next to the trigger valve on the cleaning tool that allows the operator to crack open the water flow into the vacuum hose. This is used to keep the water in motion to allow for more accurate water temperature sensing and to keep the water temperature from spiking too high. You have to remember that engine exhaust can get as high as 1200 degrees F. and if you receive a phone call or your customer interrupts your cleaning and you quit using water, the water in the heat exchanger could spike to 500 degrees F. The disadvantaged to bypass wands, is they use more water and you are allowing some of the BTU's of heat to leave the machine and never hit the carpet. If a truck-mounted carpet cleaning machine does need bypass tools, then it has some type of either exhaust diverter system in place or build in water motion system that takes a small percent of this hot water and sprays it back into the fresh water tank. The fresh water tank or pump will have a pump safety sensor on it to take super heated fresh water to the waste tank only if the fresh water tank is getting over 145 degrees F.
