Failed regulators are usually not discovered until someone notices a leaky relief valve on the water heater or a supply hose bursts. ![]() In our hard water area (Northern California), regulators last roughly five to 10 years. There's an advantage to using both an expansion tank and a relief valve in homes using a pressure regulator. It's best to keep pressure as steady as can be and as low as possible (but still maintain good flow), particularly if water hammer is a concern. With the other methods, the pressure must go up 15 to 30 psi to operate the relief or fill valve. Pressure will fluctuate very little with a correctly sized and inflated expansion tank. The expansion tank offers a benefit the others cannot. When is an Expansion Tank the Best Choice? It has the advantage of being able to be used in any climate, not just where freezing isn't a worry. This is a toilet fill valve that is designed to relieve any pressure over 80 psi. Perhaps a better alternative is the Watts Governor 80. However, relief valves used this way are made to operate so often they can fail quickly and leak all the time. Often it was installed on outdoor plumbing and placed to drip on a flowerbed it was put close to the front door so the owner would notice if it dripped too much. For folks who have to deal with periodic water rationing, high water pressure causes not only higher water bills, but threatening letters from the water company and perhaps even a flow restrictor at the meter.īefore expansion tanks were common, plumbers used to put an adjustable pressure relief valve in the system, anywhere downstream of the regulator. High pressure caused by thermal expansion produces uneven water flow, and it magnifies water hammer. Sink and washing machine hoses are more likely to burst. ![]() High pressure causes faucet washers and automatic valves to wear out faster. Water heaters suffer when high pressure cracks the glass lining, and you may even hear them groan as the metal flexes. High-pressure makes relief valves leak, hiking the bill even higher. High water pressure will add roughly 30 percent to the water bill just because more water flows out the tap every time it's used. In either case, the plumbing is being subjected to high pressure and to large pressure fluctuations multiple times daily, and something is going to wear out. So with those older ones and with backflow preventers, the expanding water will simply build up pressure until the relief valve on the water heater drips (lucky) or something in the plumbing system pops (unlucky). (Note that in hard water areas, the check valve in the regulator tends to get stuck and so should not be depended on for protection.) Older regulators usually don't have that check valve. Assuming the water heater's relief valve kicks in as it should, this backflow will happen only if the line pressure is less than 150 psi. With a newer one in place, expanding water will pressurize the system up to line pressure, then flow into the main line through a check valve built into the regulator. Newer pressure regulators operate differently from most older ones. Building codes now require pressure regulators when pressure exceeds 80 psi, and backflow preventers are sometimes required to prevent cross-contamination. As increased population has led to increased water demand, public water pressure has been more difficult to control. ![]() But thermal expansion is becoming more of a problem now because backflow preventers and pressure regulators are being used more frequently. In most cases, expanding water simply flows back into the main supply to the house. The main reason to have an expansion tank in a domestic water system is to prevent the damage from high water pressure, defined as anything over 80 psi. Though usually not a problem, thermal expansion can lead to high water pressure and cause expensive problems. This thermal expansion occurs in all residential and commercial plumbing systems that have tank-type water heaters. When cold water is heated, the water expands. You want to have a good understanding of expansion tanks so you can recognize and solve thermal expansion problems for your clients.
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