When inspecting a hot water boiler system, always look for backflow protection. The device should be located somewhere between the pressure-reducing valve and the water service connection. When installing a Backflow Preventer with Intermediate Atmospheric Vent, a common mistake is to locate it on the low pressure side of the system. When installed on the low side, the device will typically drip water from the vent as it needs about 25 pounds of pressure to function properly. Because of the drip, the vent gets plugged. Installing the device on the low side of the system and/or plugging the vent can keep the backflow preventer from working properly. Be
sure to recommend further evaluation by a qualified professional if you discover an improperly installed, plugged, dripping or missing backflow preventer on a hot water boiler system.