Hot Water Heater Expansion Tank Pressure

In the past the expanding water in the tank would simply drain back out into the municipal water supply where it came from.

Hot water heater expansion tank pressure. You install the expansion tank down the line from the inlet valve that sends hot water into your home. Inside the tank has a rubber diaphragm at around the mid point of the tank. When the pressure supplied to your home is at a suitable level between 40 and 80 ps and has a prv or check valve the thermal expansion tank enters. Most expansion tanks come pressurized to 12 40 psi but before you install the tank you have to match the system pressure.

This pressure is adjustable by adding air to the expansion tank up to the maximum rated pressure typically up to 80 psi. It has a diaphragm separating both. Most of the time your tank is half water and half air. If the extra volume has nowhere to go it pushes on the walls of your plumbing.

The way that it works is this. Prevents constant high pressure fluctuations caused by thermal expansion in closed loop systems. Use a tire gauge to check the pressure. When water is heated or a hot water faucet is turned off abruptly pressure builds from expanding water molecules.

When your water thermally expands a water heater expansion tank prevents unwanted increases in pressure. The expansion tank s purpose is to protect your house s hot water system from excessive pressure which can cause damage to fixtures your water heater lines and or fittings. When pressure increases the diaphragm is pushed upward. The calculators provide the minimum size expansion tank expressed in gallons.

Pressurized air goes below the diaphragm in the bottom half of the tank and water flows in and out of the top half of the tank. Use a bicycle pump or compressor to fill the tank to match the system pressure you noted earlier. It is rare that a water heater is completely emptied and has only cold water in it. Today the water main is designed to prevent the backwards release of pressure known as backflow by employing a check valve.

The water heater expansion tank serves as an overflow receptacle by absorbing excess water volume that occurs when water is heated as well as absorbing fluctuations in the incoming water supply pressure. Start by removing the protective cover from the air valve on the tank. This process is called thermal expansion and it can cause strain on your plumbing system. Tank pre pressure is usually factory set at 40 psi.

Water expands by roughly 2 as it heats up from 50 f to 120 f. Because water will expand when heated the excess pressure inside the water heater tank needs to be released. It s estimated for example that the cold water in a standard 50 gallon water heater expands to 52 gallons when heated to 120 degrees fahrenheit.