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Boiler with indirect loop

NEtech
NEtech Member Posts: 17
in Domestic Hot Water

So I am a residential tech I've been to a few calls with newly installed boilers by my company. I have found air locked indirect loops. I observed that there was no purging device on loop but a spirovent on the supply for entire boiler.

How is loop getting air? Can air get past spirovent somehow

Comments

  • mikedo
    mikedo Member Posts: 232

    need piping diagram pic tures. is there a vent on top of indirect ?

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,680

    I am assuming that the DHW has worked in the past.

    If that is case, then the original installer was able to purge the air in some fashion. Some tanks, like the Weil McLain Plus and the older Triangle Tube tanks have a fitting on the top that is supposed to have an automatic air vent, (that ends up leaking water) on the top of the tank. That is where you get that air out.

    If it is a Coil heat exchanger in the tank, then based on the circulator location, sometimes you can loosen a flange bolt to let air out until water leaks out. Another trick is to get the static boiler pressure up to about 25 PSI to compress the air pocket enough for the pump's differential pressure to move that air pocket down the pipe, just enough to start some circulation that will move the air to the Spirovent. Be sure to release that extra pressure after the air is purged.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • GroundUp
    GroundUp Member Posts: 2,167

    Either something is piped wrong and a vent is pulling in air, or the system was not properly purged at commissioning and the air got hung up at the indirect.

  • mattmia2
    mattmia2 Member Posts: 11,116

    If the system is leaking somewhere the fresh water will have air dissolved in it that will come out. Air can move past the air separator, it is more to take some out as it passes through than a dead block of all air and it will get it more or less all out as it circulates over usually a short period of time.

    They likely used valving at the boiler and possibly a hose connected to a drain somewhere to flush water through it to get enough air out for it to circulate.

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