Navien NCB 240 E

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New York
Hi Everyone. First off I appreciate all feed back and thank everyone for being the site. I just bought a home that had a Navien NCB 240E installed.
My home is about 2500 SF. 2 zones with hydronic coils. There is no outdoor reset sensor installed on the boiler. I reset the boiler to factory defaults.
Since there is not outdoor reset control, I am trying to dial in the boiler as best as I can.

I have the heating supply set to 140, and the DHW set to 120. I have not messed with the parameters in the installer setting. Currently in NY Long Island we are at 30 degrees overnight. I do not have night setbacks on my Stats.

Should I be adjusting the F- Capacity below 100% since I am assuming the boiler is over sized or leave the factory defaults as is.

Thanks again.


Well-Known Member
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Peace valley missouri
Return water to get your 95% efficiency has to be under 140°f above drops to 87%. Leave it at 100% it will adjust itself unless you know the capacity of the fan coils. If you get outdoor reset look at b setting. Fan coils usually need at least 160° supply water.
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