Rinnai Code 10: No Gas Supply or Gas Valve Failure

Quick Answer

Rinnai Code 10 indicates the unit attempted to open the gas valve and begin a heating cycle but could not detect gas flow. The first thing to check is whether other gas appliances in the home are working. If a stove or furnace is also out, the issue is upstream of the water heater and requires the gas utility.

In my experience, Code 10 is usually the result of a simple oversight like a bumped gas valve or an empty propane tank. While it sounds serious, it rarely means the water heater itself is broken. I often see this after a gas meter upgrade or when a service technician forgets to turn the gas back on after a different repair. If your other gas appliances are working, we can narrow it down to the unit's specific supply line or internal solenoids.

RinnaiWaterheaterSeverity: high82% DIY Success

Time to Fix

15–60 min

Difficulty

beginner

Parts Cost

$20 – $280

Tools Needed

Multimeter, Manometer (for gas pressure verification)

What Does the 10 Code Mean?

Think of Code 10 as your Rinnai telling you it is hungry but the kitchen is closed. It is trying to open the internal valves, but there is no pressure behind them. Before you start tearing the unit apart, we need to verify that fuel is actually reaching the cabinet. Nine times out of ten, the solution is outside the water heater rather than inside it.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Gas supply valve to the unit closed or only partially open40%

Gas utility outage or service interruption in the area24%

Gas supply pressure below unit minimum (4 in WC for NG, 8 in WC for LP)14%

Gas meter undersized for the total connected load12%

Gas valve solenoid coil failure inside the unit10%

Symptoms You May Notice

Code 10 on controller display
No ignition attempts heard (clicking) when demand is made
All other gas appliances in home also not working (if utility issue)
Unit acts completely dead when hot water tap is opened
No flame during any startup attempt

Can you reset a Rinnai waterheater to clear the 10 code?

To clear the code, press the Power button on your controller to turn the unit off, then back on. If you just restored gas service, you might have air trapped in the lines. You may need to cycle the power a few times to purge that air before the burner finally catches. Just be patient, as it takes a moment for the gas to reach the ignition point.

Tools Required for Diagnosis

MultimeterManometer (for gas pressure verification)Gas leak detector solution or electronic leak detectorScrewdriver set

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
Gas Valve AssemblyContact Rinnai with model number · $150–$280	Contact Rinnai with model number	$150 – $280
Gas Pressure Regulator (LP installations)Varies by tank size · $20–$60	Varies by tank size	$20 – $60

Frequently Asked Questions

Is Rinnai Code 10 dangerous?

Code 10 is actually a safety feature doing its job. The control board realizes there is no fuel to burn, so it stops the ignition process to prevent any issues. It is not dangerous by itself, but it is a signal that your gas supply is interrupted. The only real danger is if the code was caused by a physical leak, which is why I always recommend a quick sniff test around the unit before you start troubleshooting.

My gas stove works but my Rinnai still shows Code 10. What now?

If the stove has a flame but the Rinnai is throwing Code 10, the problem is between the main gas line and the water heater. It could be a dedicated shut-off valve that was left closed, a kinked flexible gas connector, or a failure of the internal gas valve solenoids. Tankless units are very sensitive to pressure drops, so even if a stove works, the Rinnai might not be getting the volume it needs to fire up safely.

How long does it take for a Rinnai to fire after gas supply is restored?

It depends on how much air got into the lines. If the gas was off for a while, there is a pocket of air that needs to be pushed through the system. You might see Code 11, which is an ignition failure, during this process. Usually, after two or three reset cycles, the air is purged and the gas reaches the burner. Once you hear that steady roar of the flame, you are good to go.

Can Code 10 be caused by a software glitch?

In fifteen years, I have only seen a handful of boards cause a Code 10. It is almost always a mechanical or supply issue. However, if you have perfect gas pressure and the solenoids test perfectly with your multimeter, the circuit board might not be sending the signal to open the valves. At that point, you are looking at a control board replacement, but make sure a pro confirms that first before spending the money.

What gas pressure does a Rinnai water heater require?

Rinnai units are picky about pressure. Natural gas needs to stay between 4 and 10.5 inches of water column. For propane, you need 8 to 14 inches. The trick is measuring it while the unit is under load. If the pressure is 7 inches at rest but falls to 3 inches when it tries to spark, the unit will trip a Code 10 every single time because the gas line is likely too small for the unit's high BTU demand.

Related Rinnai Waterheater Error Codes

Code: HUBRinnai Tankless Water Heater Error Codes: Complete Guide Code: 11Rinnai Code 11: No Ignition Fix for RU and V Series Tankless Heaters Code: 12Rinnai Code 12: Flame Failure During Operation Code: RESETHow to Reset a Rinnai Tankless Water Heater: All Models Guide

Same Fix on Other Brands

Navien waterheaterE003: Navien E003 Error Code: Ignition Failure Fix for NPE and NCB Series

Models Known to Experience 10 Errors

This repair applies to most Rinnai waterheaters with this error code. Common model numbers include:

RUR98iN, RU199iN, RU98eN, V65iN, RL75iN, RU160iP

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 14, 2026