Watch for other Navien issues
We have a Navien CR-240 A LNG installed and we a very unhappy. Within two years we have had the water flow sensor replaced, then the circuit board replaced (which they were very slow to decide to send and from investigation this is a major issue with the units, as is the water flow sensor) and now we have had a minor flood as a result of a cracked Adapter A 90 degree fitting in the unit. They keep sending parts but don't seem to think that there is any need to replace the unit. So far we have spent a lot of $ on plumbers and contractor time. I guess they do replace under warranty one piece at a time.