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Paul SPaul S Member Posts: 1,219
Hey everyone I got a service call for a Navien combi boiler...the problem the customer was having was no hot water at all....when I got to call I immemediatsky called Navien tech support...they told me that the flow sensor in the domestic hot water inlet was not sensing they told me to remove the sensor and check to see if it was dirty?....the sensor look like a tiny pump impeller....I checked sensor all looked good...the Navien does work when I hook a hose to the domestic hot water does not work when I open any faucet or even the tub spout....I believe the unit turns on once it senses 0.5 GPM flowing through the DHW side....I tried getting Navien to send me a New sensor but they said it works?? Ours under warranty....had anyone experienced these type of issues with this boiler? Thanks Paul S
ASM Mechanical Company
Located in Staten Island NY
Servicing all 5 boroughs of NYC.
[email protected]


  • Jamie HallJamie Hall Member Posts: 6,653

    Disclaimer: I know practically nothing about Naviens!  However, this is one of those rare occasions when I would try parts swapping as a diagnostic effort.  If the thing works with a hose (up towards 5 gpm) but not with any of the other faucets etc. singly (I presume) it suggests to me that a) the sensor works but b) not at a low enough flow -- which, for all practical purposes, means it doesn't work.  It could be sticky.  It could have an internal short reducing its output at low flow...

    Just meandering thoughts.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
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