Boiler Expansion Tank

Greetings all
Towards the tail-end of the heating season (which I'm not entirely convinced is over here in Ohio, based on the cool, grey and rainy weekends recently), I noticed the pressure in my Crown Aruba boiler was reading lower than the normal 15-18 psi, at around 8psi. After I shut the boiler down and allowed the system to cool, I checked the air pressure in the Amtrol (Fill-Trol model 109) expansion tank with a digital pressure gauge and it read only 3.5psi.
Can these things leak?
I replaced it only a coupla years ago, though I never bothered to see if the 'factory fill' of 12psi was actually there. Any reason why I can't 'pump it up' slowly back to 12 psi and see what happens?
Thanks in advance...
Pete in Cleveland OH
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boiler system = not a playground. if you read all the manuals on the collection of all devices which make up your system, it will show the range of capacities and adjustments.but it's best to have an hvac man visit to give you the adjustments and info for your labeling of each pipe and wire and valve and the step-by-step for your annual checklist.
Pete D wrote:

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wrote:

It may not be actually "leaking", but yes, they can slowly lose air. Pump it back to 12 PSI and periodically check it.
Doug
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Expansion tank, that is for water expansion and has air in it, your water pressure is what you are reading off the boiler, should water=air pressure? To me whats important is boiler water pressure, not the tank.
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Sure, unless one has a big leak.
Nick
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snipped-for-privacy@ece.villanova.edu wrote:

Except subtract about 1/2 psi for every vertical foot you go up.
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