This Old House – September 2019

(sharon) #1

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4 > Pressure- Reducing Valve


“This device goes on the water main coming into a


building in areas where the municipal water is supplied


at a pressure that is too high, anything over 75 psi. Its


spring-loaded core acts like a shock absorber, sending


water at just the right amount of pressure—we look for


45 to 50 psi—into the house.”


5 > Standard Stop-and- Waste Valve


“The most common plumbing valves all stop and


regulate the fl ow of water, but their design has evolved


over the years. The standard stop-and-waste valve,


which is still used for branch lines in houses, relies on a


rubber washer that will wear out eventually. A better


option is the gate valve, which has a guillotine bronze


wedge driven down into a gate to close off water; it has


long been used on water mains. But it has its


limitations, too; over time electrolysis can rot the


threads into a closed position.”


6 > Gas-Fired Tank-Type


Water Heater


“No cutaway has given us more mileage than Old


Rusty Water Heater. It’s the only way you can see


the important components inside—the dip tube, the


anode rod, and the steel tank construction—and


get a sense of why every water heater has a limited


life span due to corrosion.”


7 > Ball Valve


“The invention of the ball valve was revolutionary. It


has a stainless-steel ball inserted next to a special


material that will never wear out. It is clearly the valve


of choice. Many plumbers now use ball valves


everywhere for their long service life.”


8 > Temperature and Pressure


Relief Valve


“This is absolutely one of the most important safety


devices in a house, designed to relieve pressure if a


water heater ever gets to an unsafe pressure. We don’t


want water heaters ever going airborne again.”


9 > Water-Hammer Arrester


“So many plumbing complaints begin with, ‘It makes a


noise like this...’ and that’s generally because too much


water is moving through a pipe and then stopping


suddenly. That’s where the ‘water hammer’ reference


comes in. An arrester is basically a chamber that sits


inside the plumbing system with a neoprene gasket


inside and air pressure on one side and water on the


other. Oncoming water hits the equivalent of a


trampoline—the gasket, which acts like a shock


absorber, then lets water pass through.”

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