I have a water expansion tank (5 gallons) installed on a new water heater (40 gallons) and my houses PSI is at 70-80.

The tank came precharged at 25psi.

I know that I am supposed to match my home water pressure and that of the tanks but I wonder if this does not have to happen immediately.

If I had to do it immediately, do I have to shut down the main and can I pump using an electric pump or do I have to disconnect the plumbing and remove the tank altogether before I can pump it?

  • Didn't instructions come with the expansion tank? If you decide to increase the pressure in the bladder in the tank, you would not have to turn anything off. I would turn on a cold water faucet on low and use a bicycle pump with pressure gauge to add air. – Jim Stewart Feb 11 at 15:29

If it is a "bladder tank" that is, it has a balloon inside to contain the air needed for pressure, do not add any more air to it. when the tank fills with water, the balloon will reduce in size since it is not at the same pressure as the water entering the tank. After the same amount of air is compressed in the balloon/bladder, the pressure will increase to match the incoming pressure. This aids in the cycling of the water pump. Either too much or too little air will increase the amount of times the pump runs to maintain pressure, making the system work harder.

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