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Pressure rise expansion tank?

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RobertHVACPro
RobertHVACPro Member Posts: 3
in Radiant Heating
I was doing a boiler start up and set the system static pressure at 12 psi and the expansion tank pressure at 12 psi. After the system came up to temperature (180°F) the pressure was at 14.5 psi. I checked the sizing of my tank and its sized properly per amtrols sizing chart for a 125k btu CGi-5. Is this normal or is there a problem?

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  • RobertHVACPro
    RobertHVACPro Member Posts: 3
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    Pic of install
  • JUGHNE
    JUGHNE Member Posts: 11,061
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    Are you pumping towards the tank or away from it?
  • hot_rod
    hot_rod Member Posts: 22,132
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    2 psi increase is not an issue.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2RobertHVACPro
  • RobertHVACPro
    RobertHVACPro Member Posts: 3
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    I’m “ pumping away” 😎
    JUGHNE
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,520
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    @RobertHVACPro

    2 psi rise is fine. In fact a lot of systems will go to 20psi or more when hot. It's not an issue unless you get over 24psi or so. 80% of the releif valve set point shouldn't be an issue. The larger the expansion tank the less pressure rise you get.
    RobertHVACPro

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