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Hydronic Spirovent

If a spirovent cant be placed with the expansion tank where should it go. The tank is is teed right off the supply and before the pump, is it better to be placed after the circulator where its hottest? Or at the lowest pressure point of the system which would be right before the boiler on the return side. Thanks

(Baseboard pumping away for 3 zones. 2 story home)


  • unclejohn
    unclejohn Member Posts: 1,833
    Install the Spirovent
    for Optimum Performance
    Ideal placement of the Spirovent Junior is based on microbubble
    separation and Henry’s Law*. Simply put, Henry’s Law states that air
    is released from water as the temperature increases or the pressure
    decreases. In hydronic heating systems, the Spirovent should be
    installed in the boiler supply line where the temperature is highest.
    Should the circulator be located on the supply line as well, the Spirovent
    should be installed between the boiler and the circulator where pressure
    is also the lowest.
  • JOutterbridge
    JOutterbridge Member Posts: 15
    I completely understand that and get the concept. What i'm asking is what is the best location if it CANNOT fit before the pump on the supply side of the boiler. Which is more efficient, the lowest pressure possible? Or the highest temperature possible, which would have the spirovent placed directly AFTER the pump.
    Also the system flow is pretty low if that matters. Very little head.


    Jon O.
  • hot_rod
    hot_rod Member Posts: 22,261
    either location for the Spiro, as close to the hottest point in the piping, ideally. I've seen then on return piping also and they work fine. Just as long as all the flow makes it to the device it will grab big and small air.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JOutterbridge
    JOutterbridge Member Posts: 15
    Thanks Hot Rod. I'll do the hottest and highest spot then vs the lower temp and lower pressure return. All the system flow will be going through it, very basic setup.
  • JOutterbridge
    JOutterbridge Member Posts: 15
    Air seems to be almost non existent in the baseboard now in all zones. System is running quieter than ever with the tank before the pump of course but the spirovent after it on the supply. Will monitor the next few weeks. 2 days and still no noises or cavitation on the speed settings used