Rinnai V65i Tankless unit shuts off during shower.

JohnRB

I have a newly installed Rinnai V65i natural gas water heater the shuts down after 2 to 5 minutes of use when either of the two showers in the house are running. Only seems to be s problem with the showers\baths, not faucets. It flashes a error code 10 air flow error. It only seems to happen when the unit has not been on for a while.

Now after this shut down and code, if you wait a minute and turn the shower back on, it will run and heat the water fine without any problems. We ran for about 15 minutes before we shut it off. So the problem only seems to occur when the unit has been sitting idle for awhile.

All vent looks clear and and obstructed. Thank you and I appreciate any comments, john.

GGross

I would start by taking apart the vent and verifying that the internal pipe (which should be your flue) is correctly sealed and not leaking back into the outer pipe (which should be the intake) the first pic kind of looks like the internal pipe terminates before the termination fitting, but it is hard to tell. After that it looks like the condensate drain does not have a trap which could have a negative impact on the equipment, there is no dirt leg on your gas line, the bend in the flex is a bit much for my liking but i get it... and I normally would like to see copper on your relief valve as it is possible if we are getting blow off that it could be too hot for the pex

JohnRB

Thank you for the reply. Exhaust does not terminate before end cap, must be the photo. We will definitely disassemble vent flue and confirm no cross contamination.