Navien cr240r burner starts then shuts off over and over again.

[Twowaxhack]

When you replace a brain board in a Rinnai the brain board itself must be programmed for high and low fire.

I’m not sure how Navien does their brain board swaps, if it requires programming.

 

[Clark]

I spoke with a technician and they thought gas air mix is the culprit. Abit above my pay grade. But I got it tweaked so it seems to be consistently producing hot water again!