Gas water heaters · USA, Australia & worldwide

Rinnai tankless water heater error 10

Your Rinnai tankless water heater flashes or beeps "10" and hot water stopped. Rinnai lists this as an air supply or exhaust blockage.

Short answer

Air supply or exhaust blockage: the heater cannot breathe in or vent out properly.

What 10 means on Rinnai

On Rinnai tankless (continuous-flow) gas water heaters, code 10 means air supply or exhaust blockage. The unit shut down because it could not get enough combustion air or push exhaust out, which is a safety lock-out.

Safety first. If you smell gas, do not touch switches: leave, then call your gas emergency number from outside. Only a licensed gas fitter/plumber may open the unit, change venting or adjust gas pressure. Owners may check that outside vents are clear and reset the unit. More safety notes

Step-by-step fix

  1. Look at the outside vent

    From outside, check the vent and intake terminals for leaves, snow, ice, nests or anything leaning against them. Clear what you can reach safely by hand.

  2. Clean the air filter (indoor units)

    Many indoor Rinnai models have a small air filter on the unit. Your manual shows where; clean it if dusty.

  3. Reset the unit

    Turn the heater off at the controller or power, wait a minute and turn it on again. Run hot water to test.

  4. Call a Rinnai-trained technicianCall a pro

    If 10 returns, a licensed technician should check vent length and materials, connections, the fan and check valve, and the altitude/DIP settings. Do not alter venting yourself.

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Common causes

  • Outdoor vent or air intake blocked (leaves, snow, nests, debris)
  • Internal air filter dirty (indoor models)
  • Vent run too long, wrong materials or loose joints
  • Fan wheel or check valve dirty or sticking
  • High-altitude or DIP-switch settings wrong for the installation

How to prevent it

  • Keep outdoor vents and intakes clear of plants, snow and stored items
  • Have the unit serviced by a licensed technician

Tools & parts you may need

  • Torch, gloves, soft brush for the outside terminal

FAQ

Is Rinnai code 10 dangerous?

The heater shuts down to protect you. Blocked venting can push exhaust gases back, so do not keep resetting it if 10 returns: call a licensed technician.

Why did code 10 appear after snow or wind?

Snow drifts, ice and wind-blown leaves are common causes. Clearing the vent and resetting often fixes it.

Sources

Checked on 26 October 2026. Codes can differ between model generations: your own manual always wins. Spotted an error? See About & corrections.

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