What does error code 70 mean on a Rinnai tankless water heater?

PC board fault. A fault with the main circuit board.

Can I fix Rinnai code 70 myself?

Start with these safe checks: Turn the heater's power off and on once. If 70 returns, call a qualified technician.

When should I call a technician for code 70?

If 70 returns, call a qualified technician. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Rinnai tankless water heater error code

Rinnai tankless water heater code 70: PC board fault

Rinnai tankless water heaters

What 70 means

A fault with the main circuit board.

Likely causes

Board fault

Safe first checks

Turn the heater's power off and on once.

When to stop

If 70 returns, call a qualified technician.

Checked against: Rinnai: Troubleshooting Tankless Water Heater Diagnostic Codes (100000652). Codes can differ by model and year, so confirm with your owner's manual.