Navien NR240A Recirc Issue

[Mroll]

Hi All,
After a few weeks of going through the forums and trying the cheaper and easier solutions I’m now at a loss. moved into a new home with this tankless system and a dedicated recirc line. with the heater in external recirc (or internal for that matter) the burner will not activate to keep the recirculating water hot. I’ve replaced the flow sensor and the check valve As well as flushed the system extensively. the check valve was clearly faulty as the water now stays warmer, but not hot. As soon as a tap opens, burner activates and hot water is made. The pump is circulating as I can eventually feel warm water come through the return line, but not sure if it’s recirculating enough Since the burner won’t turn on. i did take the pump apart and the impeller seems to be in good shape. It does make some noise though, almost like a clicking. the unit will throw the 038E code on startup after being drained out but a quick pull of the relief valve solves that and it never returns, not sure if that is related.
not sure where to go from here, any help is appreciated!

 

[Breplum]

The process of diagnosing problems can be pretty challenging. That's why Navien tech support rarely if ever talks to not pros.
There is a service manual that Navien gave out to some of us plumbers, but, even then, it is best to talk through with tech support.
I'm afraid my recommendation is to have a listed NSS plumbing contractor come out.

 

[Sponsor]

 

[Fitter30]

Why isn't the plumber involved? How long is the recir pipe, type of pipe and number of fittings? Is there a flow read out?

 

[Mroll]

Ok thanks guys, was hoping someone may have experienced this before and could point me in the right direction but perhaps it’s unique! Will call a plumber this week.

 

[Breplum]

Look for the NSS listed providers on Navien's website. They will have some modicum of training (though, a qualifier could send out a rookie

 

[Mroll]

Update:
Plumber came out and agreed with my assessment that the pump was on its last legs. For those that want to see what your pump is flowing there are two white buttons towards the middle left of the control board. Push them simultaneously and then push the left button (hold for a second) and your flow rate will be displayed on the readout on the board. My “failed” pump was moving 0.35ish. Now that I’ve installed a new pump it’s moving 1.60-1.70.
This info would have saved me a visit from the plumber so hopefully it helps someone else out down the line. Could also be used to diagnose a failed flow sensor assuming that’s where the readout is getting it’s data.

 

[seatan]

Hi @Mroll this is quite relevant to a problem I'm trying to solve in diagnosing potential pump issues. Are you talking about the two buttons here?