Navien npe-240a2 mostly only making luke warm water

[ne31097]

Navien npe 249a2 installed in January 2023 and working fine until three weeks ago. Upon request for hot water, flow rate only reads 0.5 gpm even though actual flow is more like 3-4. Hot temp out is only a temp rise of about 5 degrees (75deg f). No error codes. Sometimes upon hot water request it just keeps cycling between startup and post purge. Sometimes it reads 3-4 gpm and actually makes hot water, but this is becoming very rare. Again no error codes ever. I’m doubtful it is the flow sensor (don’t worry, plumber is replacing it when the part comes) because it is a strange failure to read 0.5 gpm. I know the impeller is turning, there is no gunk or scale in the screens or flow sensor. Could it be anything else?

 

[Breplum]

Your Navien is under both parts and labor warranty. Use plumbers listed on Navien's site so they can get paid with ease (though, Navien takes two months to pay us, it is still reliable). The flow sensor is not reading correctly. I have encountered this, even on newish units and replacing flow sensor solves the problem.

 

[Sponsor]

 

[ne31097]

Your Navien is under both parts and labor warranty. Use plumbers listed on Navien's site so they can get paid with ease (though, Navien takes two months to pay us, it is still reliable). The flow sensor is not reading correctly. I have encountered this, even on newish units and replacing flow sensor solves the problem.

I’m working with navien plumber. Just worried flow sensor is not the issue. Good to know it should be fixed when flow sensor arrives.

 

[Breplum]

And lucky for you, the tech call-in line at Navien will help if it still is problematic.

 

[DenverSam]

Are you using the external recirc line feature?

 

[vort1967]

I am having the same issue with only luke warm water most of the time with low flow on the sensor. I replaced the flow sensor and still the same issue. I also descaled the unit and it was clean. I have recirculation turned off.

 

[Machine_Ruse]

I am having the same issue with only luke warm water most of the time with low flow on the sensor. I replaced the flow sensor and still the same issue. I also descaled the unit and it was clean. I have recirculation turned off.

I know it's a month late, but if you haven't fixed the problem you should look at the check valve. A sticking check valve would cause all of the symptoms you describe. It's about $3 and 10 minutes to replace. See here:

Navien 240A not getting generating very hot water

I'm trying to diagnose what is going on with my Navien 240A hot water heater running on natural gas. We've had it for about 6 years, and it's worked fine up until now. It gets descaled each year with vinegar and the filters get cleaned (air and cold water intake). Yesterday my family complained...

terrylove.com