Rinnai RXP160IN Sensei RXP 9 GPM 120 Volt Residential Indoor Liquid Propane / Natural Gas Tankless Water Heater with Integrated Recirculation Pump

Much noisier than specified in manual

The manual specifies a noise level of 48 dB. Although the unit is fairly quiet while heating water, once the flow stops, it starts emitting a loud (60+dB) moan that lasts 3 or 4 minutes. Although I haven't tried it in recirculation mode, I imagine most people would find this completely unacceptable as it comes on and off several times an hour. Installation instructions (even online) seem to be out of date in terms of the wireless accessories and how to use their app. Other than that, it seems to do a good job heating water to the desired temperature.