Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

System pressure loss

solradman Member Posts: 58
Replaced a boiler for a fin tube baseboard system which had non-barrier tubing supply the baseboards. System has a flat plate heat exchanger, a separate pressure tank, air vent, VS stainless steel pump and 4 port manifold with actuators for zoning. Flushed each loop before start up and set system pressure per gauge at around 12 PSI. System loses pressure and needs to be refilled every couple of days by adding more water. Have checked as much of the lines as possible and have not found any sign of leakage at any fitting or the the baseboards. Any ideas will be helpful.


  • GroundUp
    GroundUp Member Posts: 1,957
    Probably just working air out of each loop as it heats and expands. Was the system holding pressure prior to you working on it?
  • HomerJSmith
    HomerJSmith Member Posts: 2,511
    edited April 2020
    Is your pressure tank a bladder tank and pressurized (inflated) to 12 psi? How did you set the pressure per gauge to 12 psi? Why do you manually have to add water and why isn't it done automatically?

    Why do you think you have non barrier pex? Does your manifold have air vents on it and did you open them to bleed the air out of the zones? Does the manifold have flow controls for each zone on it?