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New optimal fill system location? (The Youngster)

Brad White
Brad White Member Posts: 2,398
allowing the boiler to take that raw oxygenated water and getting it to critical (air release) temperature upstream of the air separator. That makes sense to me, rather than introducing the air-laden water to go around and around at least in theory.

I am getting away from using fixed (hard-connected) fill points and opting instead for Axiom or other automatic feeders with limited volume, or just filling the system and letting it be (with proper LWCO protection of course).

Personally, once you get the air out (heated and "boiled off" after initial purging especially), I cannot see a need for a hard fixed connection unless code requires.

(On commercial/institutional work, we specify a flow switch to alarm any unattended water flow for over 30 seconds. That would signify a leak somewhere in the system and send an alarm via the ATC system.)

For years the connection has been at a point between the expansion tank and the air separator without a problem.

But the "initial heating" rationale I could justify.

My $0.02

"If you do not know the answer, say, "I do not know the answer", and you will be correct!"

-Ernie White, my Dad


  • Josh_10
    Josh_10 Member Posts: 787

    I just got around to reading the July 2007 journal for Idonics by Caleffi. I noticed that they claim the optimal position in the system for the fill system is in the return of the boiler, with the micro-absorber on the supply.

    I understand the micro bubble air absorbers work best where the solubility of absorbed gases in the water are at their lowest (hottest point).

    But why the fill system location on the return? I also noticed Siggy doing this and asked him at the last seminar I attended. He told me about micro absorption but not the fill location.

    So why is it optimal in the return? Why not connected with the absorber upstream of the circ? Pumping away from the PONPC?

    Are we in a new generation now, where micro absorbers don't need to be located at the PONPC?
  • Josh_10
    Josh_10 Member Posts: 787

    I had the same thoughts Brad. I didn't know for sure though, hence the questioning.

    In fact you bring up an interesting topic in and of itself regarding whether you should have automatic make-up. I think for now it should be mandatory unless the user understands how to monitor their hydronic system.

    I have a couple reservations before changing though. I would like to see the make up water take a pass through the dirt separator before entering the boiler. Especially mod/con boilers with tight heat exchangers.

    It would be fun to debate the issue with some air separation and dirt removal guru's.

  • It's funny you say that Josh, when I would say I wish that automatic fill were NOT ALLOWED unless the user knows how to operate and check their system.

    I've seen too many systems eat themselves alive due to a small drip drip somewhere unnoticed, fill valve did its job, and the boiler just rusted out, clogging the rest of the system while it died.

    Personally, I'm right there with Brad. But, we haven't made the transition ourselves just yet...
  • Josh_10
    Josh_10 Member Posts: 787

    Well I definitely don't disagree. I too have seen a few go south from mineral deposits. But until we change as an industry I can't really change as a contractor. As much as I would like make the change myself.

This discussion has been closed.