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Is it necessary to use the Autofeed connection on my Navien combi boiler?

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JohnJr
JohnJr Member Posts: 14
in THE MAIN WALL
Hello, I've got a NCB 210E Navien combi boiler. On the bottom of the boiler is an autofeed connection. Is it absolutely necessary to have this connection used on the boiler? I'd like to hear some positives and negatives about using and not using this connection. Thanks.

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  • Jamie Hall
    Jamie Hall Member Posts: 23,289
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    The positive is real simple: if everything is set up right, you don't have to worry about the boiler running low on water or sucking air at the higher elevations.

    The negative is also simple: you absolutely must keep an eye on the system pressure. Not daily, perhaps, but certainly a time or two a week. Without the autofeed, the system is not a turn it on and forget it system.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Derheatmeister
    Derheatmeister Member Posts: 1,543
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    Ahh the dreaded Auto feed Question...
    Leave it on and you could possibly flood a home..
    Leave it off and you could possibly Dry fire a Boiler, Have a oxygen ingest problem, Ruin circulating pumps, Freeze a home..
    I recommend not connecting to the domestic and using a pressure assits or a feeder such as the Axiom with an Alarm https://www.supplyhouse.com/Axiom-DMF150-DMF150-Digital-PRESSURE-PAL-Hydronic-Mini-System-Feeder-4-6-Gallon
  • Jamie Hall
    Jamie Hall Member Posts: 23,289
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    That gadget will wok, @Derheatmeister -- but I would use it only if, when it fed, it also shut down the system -- since when it feeds it is indicative of a leak. It is good for minor leaks, though -- assuming one remembers to look at the display.

    Truth is, there really isn't a good answer for the dreaded question, and it's implied in that last phrase -- "assuming one remembers to..." pay attention. An autofeeder with no meter? You may not realise you have a leak. An autofeeder and a big leak? Yeah, a real problem (I've seen it). No autofeeder and a leak of any size? If no one's paying attention, no heat and a good chance of freezing the building.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • HVACNUT
    HVACNUT Member Posts: 5,835
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    The Navien has it's own built in pressure reducing valve but you don't need to use it. 
  • Derheatmeister
    Derheatmeister Member Posts: 1,543
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    As mentioned above the Alarm is a big part of this equation..
    Our pressure assist setup can be upgraded with a Low pressure switch which can be intergraded with a notification system such as a Older style Ecobee 2 , BACNET or a regular alarm panel. We have many systems that we monitor this way :)
    The Axiom can also make or Break a contact which can be used for all kinds of things...Strobe lights,Alarm interfaces,Really annoying noise.. :D

    On most systems when the Low pressure Notification comes in we still have plenty time to react towards this situation..
    Just the way we like to do it..

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