Noise from Rinnai R53

[Dwight Reed]

We bought a 10 yo house about 3 years ago. It has a Rinnai R53 tankless natural gas water heater with a recirc system with a 6 gal electric buffer tank. When we draw hot water from the system we can hear the hear the R53 all through the house. During the day it's not a problem but the system seems to cycle periodically throughout the night (even when we are not drawing water). My main question is, is this normal or should we be looking for a leak? We have a guest bedroom adjacent to the furnace/water heater room and the noise is quite loud in there. I'm thinking if the cycling is normal, I may have to turn the R53 off at night but leave the 6 gal tank on. That way we should still have some hot water at night but not have to listen to the R53. Any opinions or advise?

Thanks,

Dewey

 

[Fitter30]

Have you done the yearly maintenance cleaning the heat exchanger with vinegar or commercial for cleaner?