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Fill, vent air, purge, 3/8" PEX, 25ft elevation change

GIJoe Member Posts: 1
I have a Caleffi heating hot/cold manifolds with air vent, fill, isolation, and flow control.

<a href="http://www.supplyhouse.com/Caleffi-6686E5S1A-1-TwistFlow-Manifold-5-Outlets">http://www.supplyhouse.com/Caleffi-6686E5S1A-1-TwistFlow-Manifold-5-Outlets</a>

There is about 25ft elevation to small section of heating loops, between manifold and peak 3/8" PEX tube height on third story. Loop is less than 200ft total length with two 90 degree bend fittings.

Do you think I need to install a additional vent?

Or would a high flow rate (>2fps) and a good air vent at lower location get rid of air?

A good water flow rate can usually purge a hose of air.

Before I get started with the modifications, it would be great not to have to install a additional vent in weird location.



  • hot_rod
    hot_rod Member Posts: 16,300
    should be fine

    is it a radiant loop? There may not be a good method to add a high point vent.

    You would want a good air vent and hydroscopic cap for extra protection, if it is a panel radiator, for example..

    What is the total elevation from equipment room, expansion tank location, to thr highest point in that upper loop?

    Adjust the system fill pressure to assure the highest point in the piping has 5 psi. That will help assure air free operation.

    For example, 3 stories, maybe 27' from mech room to upper level 27 X.433= 11.6 , add 5 psi for a 16.6psi. call it 17 psi fill pressure.

    The expansion tank needs to be sized for the system capacity, plus the operating pressure of 17psi

    The expansion tank pre-charge would need to be adjusted to match the fill pressure you decide on. Here is a link to a expansion tank sizer.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream