Rinnai SS code: service soon reminder

Unlike most codes, SS is not a fault. It is a reminder the installer set when the heater went in, telling you it is time for routine service.

The meaning and service steps below come from Rinnai's own diagnostic code guide for its tankless water heaters.

Rinnai lists this reminder for SENSEI and SENSEI RX/CX series.

What service it is asking for

Rinnai says SS means the heat exchanger should be flushed to prevent damage from scale, and that hard water must be treated. A flush every year is typical; homes with hard water may need it more often.

How to reset it

On SENSEI models, Rinnai's instruction is to push the On/Off button on the temperature controller five times within five seconds. Reset it after the service is done, not instead of it.

How often it appears

The interval is a setting chosen at installation. Rinnai lists options for off, six months, one year and two years. Your installer can change it to match how hard your water is.

Doing the service

Flushing is a job many handy homeowners do themselves with a small pump, a bucket and white vinegar or a descaling solution. See our guide to descale a tankless water heater, or have a plumber do it during an annual service visit.

Before you call

Have the model and serial number from the rating label ready, along with the exact code and when it appears: at startup, during use, or only at high demand. Mention any recent work on the gas, water or electrical supply and when the heater was last descaled. This helps the technician bring the right parts and often saves a second visit.

See every code on our Rinnai error codes page.