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Old 11-20-2012, 10:59 PM   #1
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When to adjust PSI of expansion tank

I recently installed a pressure reducing valve, and a 4.5 gallon Watts expansion tank. The tank came preset at 20 psi, and I'm confused as to why or if the 20 psi should be increased (the instructions are rather vague). According to the Watts sizing calculator my system needs a tank larger than 3.62 gallons so I would assume that 20 psi is okay? My static pressure is 55 psi, two 50 gallon hot water heaters @ 135*. Any help is greatly appreciated.


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Old 11-21-2012, 11:07 AM   #2
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The pressure should be set two PSI below the expected system pressure, so, 53PSI.

Running with pressure too low overstretches the rubber bladder. It will fail prematurely and then you have a 0.00 gallon expansion tank.


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Old 11-21-2012, 07:48 PM   #3
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set tank pressure to equal incomming pressure....if incomming is 55 set tank to 55..ben sr
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Old 11-22-2012, 08:54 PM   #4
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Thanks! Got it adjusted.
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