Expansion Tank Pressure Test

Most expansion tanks come pressurized to 12 40 psi but before you install the tank you have to match the system pressure.

Expansion tank pressure test. Start by removing the protective cover from the air valve on the tank. These tanks are usually 2 to 3 in height. It may have caused a dangerous build up of overpressure causing bursts or cracks which ultimately lead to. When the pre charge was not to factory specifications when the air pre charge pressure needs to be increased to.

With the water pressure relieved you can now get an accurate reading from your tank. Bleed air pressure out of the water tank or add air pressure into the water tank until the tank pressure is at the desired set pressure. A properly sized and charged tank is designed to keep the system pressure about 5 0 psi lower than the pressure relief while the system is at maximum operating temperature. The test is also designed to be used on a typically sized pressure tank not on an oversized tank.

Check pressure in the tank with your pressure gauge. Expose the schrader valve same valve you d find on a bike or car tire on the bottom of the expansion tank you may have to unscrew a plastic cap and firmly press your tire pressure gauge against the valve to get a reading. If the pressure setting reads less than 12 psi it probably will since you drained water from the tank attach an air compressor or hand air. For example if you have a pressure switch setting of 30 50 psi you pressure measured at the top of the tank should read 28 psi.

But there are some circumstances in which an adjustment to the pre charge may be needed. Use a bicycle pump or compressor to fill the tank to match the system pressure you noted earlier. If the pressure is less than 12 psi you will need to add some air s add air. Pressure test the cap with a professional pressure testing device follow manufacturer s instruction.

Use a tire gauge to check the pressure. Heating boiler bladder type expansion tank compression tank pressure adjustment. Release or add air as necessary to make the pressure 2 psi below the pressure switch pump cut in setting. Check your manual for the precise rating for your expansion tank.

It is used to absorb excess water pressure. For example if your well pump pressure control switch is set to cut in start pumping water from the well at 30 psi then set the pressure tank to 30 2 28 psi. Determining the air side charge of an expansion tank in a hydronic heating system is a relatively easy task. For most installations the factory set air pre charge in an expansion tank is correct and should be left alone.

Most home pressure tanks have on average about a 5 gallon draw down or supply of water. The hot water expansion tank is a two gallon tank that hangs off of your hot water system or your boiler. Most expansion tanks require a psi reading of about 12 psi. If the cap fails to hold the rated pressure replace the cap.