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Thermal Expansion and How It Effects You
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Plumbing 01/21/11

Thermal Expansion and How It Effects You

Most homeowners are not aware that when your water heater is heating up water it causes the molecules to expand, thus causing excessive pressure on your San Diego plumbing water supply. High water pressure is bad for your plumbing system in the same way that high blood pressure is bad for your health. High water pressure can cause old pipes or hoses to burst and cause excessive stress on your faucets, washing machine solenoids, and water heaters. Additionally, most manufacturers will void their warranties if the cause of the problem is due to high water pressure in your home or business.

How Thermal Expansion Works

Simply put: when water is heated, it expands. If a 40 gallon water heater rises in temperature 50 degrees, it can cause that water to increase. In some cases that water will be dispersed back into the city pipes. There are a few things that can make Thermal Expansion a potential problem in your home. For instance, if you have a backflow preventer, Thermal Expansion will not allow the excess water pressure to be dispersed past that point back into the city. The same goes for any one-way valve or check valve between your water meter and the water heater.

If your city supplies your home with high water pressure, you probably have a pressure reducing valve on your main water service to lower the pressure. Most pressure regulators are supplied with a bypass function which allows high water pressure to dissipate back into the city once your house water pressure reaches the same pressure or higher, depending on your incoming water pressure. For example, if the city supplies water pressure of 120 PSI, your home’s water pressure can reach 120 PSI before it bypasses into the city and will stay at that pressure until it is relieved. Most homes have a water pressure of 65 PSI. The plumbing code and manufacturers’ recommendation is your water pressure is not more than 80 PSI.

The bypass mechanism of older pressure regulators tend to become clogged with sediment and calcium buildup, causing the regulator to fail. In most cases, you will have a pressure relief valve on your water heater or on your plumbing system which will relieve the pressure at 150 PSI if it is properly maintained and not stuck in the closed position. If you open a faucet, the pressure will be equalized to your normal working pressure.

How to Resolve Thermal Expansion Issues

Every home with a water heater experiences Thermal Expansion, the problem starts when the excess water has nowhere to go – which isn’t common, but does happen. There are a few solutions to Thermal Expansion, the best solution is a Thermal Expansion Tank. The way this works is based on the theory that you cannot compress water, but you can compress air. So, if you have this tank installed on your system, it has an air bladder that can be compressed. If it’s sized properly to your water heater, you will be allowed to heat up an entire tank of cold water without increasing your home’s water pressure.

Call your 1-800-BILL-HOWE today to test your water system for Thermal Expansion.



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