How To Reset Rinnai Tankless Water

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Have you ever noticed that sometimes when your Rinnai is acting up it doesn’t want to respond? The Rinnai water heater’s error code function ensures that you are always aware of any internal issues. There could be a number of different reasons for this! You might need to reset or restore the system, below we’ll go over what these error codes mean, and how to reset your Rinnai tankless hot water system.

When it comes to reliability, durability and safety Rinnai water heaters are hard to beat. Yet sometimes no matter how careful we are with our heater there can be times that you will need to reset it. A power outage or a power surge are both common reasons to reset your Rinnai tankless water heater.

Read our review of the best Rinnai Tankless Water Heaters

Other reasons your Rinnai may show an “error” code may be low water flow/pressure levels, air trapped inside the unit itself- which all require specific actions depending on what type of error it was.

Don’t be afraid of doing these things yourself. In most cases you can fix your hot water system without professional help. And if you know learn to do it yourself then save time and money by not calling in professionals who charge ridiculous rates just to flick a switch.

Error codes in Rinnai tankless water heater

Typically, Rinnai shows an error code in the form of digits that ranged between 02 and 79. Plus, error codes also include code FF, code LC-LC 9, and LC.

For factory reset purposes, Rinnai tankless water heater offers a Control-R button. It would help if you pressed this button and until the light blinks white.

Rinnai Water Heater Error Codes

There are a few different types of error codes that can show up when the heating system isn't working properly. This table will help you identify these errors and how they can affect your Rinnai Tankless Water Heater.
02There is no burners when the heater is in freeze protection mode. When there is an error code, it means that the furnace has an over temperature warning.Make sure blockages haven't been missed. Inspect your combustion chamber for obstructions and exhaust piping for clogs to see if you can find out what might be wrong with it!
03Rinnai error code 3 is when the power goes out during your bath fill. It will only happen if you are using the Rinnai continuous flow hot water heater with a wired or wireless temperature controller for filling bathtubs.Rinnai error code 03 can be fixed by turning off all hot water taps and the ON/OFF button twice. This is a simple process that should only take 10 seconds or less
05If your tankless water heater has a code 05, it is a bypass valve error. (On the model RH-180 it is an Air Filter Error)Turn the water heater off. Turn the power back on and start the tankless heater. If you have the code again, you will need to replace your bypass valve.
07The water flow rate is below the minimum required 2.1 GPMFirst, you need to check if the water is on. Then look at the filter. If it is not clogged or blocked then look at the pressure. The pressure should be about 30 psi.
10Fault code 10 is a problem with the air intake or a blocked flue.If you turn on your system off and on again, the fault code 10 might go away. If not, you need to look at what is blocking the vent and stopping airflow.
11A Rinnai fault code 11 means that there is no ignition.Check if the gas is on at the water heater, gas meter, or tank. Make sure that the igniter is working. Make sure that the heat exchanger isn't blocked and that there is enough water flowing into it so it doesn't cause short cycling.
12If you get an error code 12 on a hot water unit, it means that the flame has gone out and the water heater has not detected that there is a fire in the box.Check for incorrect gas pressure supply in your hot water unit.
Check the gas, on the gas meter or in the cylinder.
Check for water or moisture in the heater combustion chamber.
Make sure that there isn't anything blocking the inlet or outlet of the flue.
13Error Code 13 means that there is a Combustion Control Fault. This means that there is not enough, or too much gas for safe combustion.Check for incorrect gas pressure supply in your hot water unit.
Check the gas, on the gas meter or in the cylinder.
14Error 14 means your Rinnai is over heating.The issue could be the safety switch or the thermal fuses. Look for discoloration on the heat exchanger surface.
16Rinnai error code 16 means that your hot water unit has overheated and automatically shut down for safety reasons.Inspect the venting system, if there are any obstructions remove them and clean the vents. Check water flow, If not enough cold water is coming in, the temperature of the heater may be too hot. See if there are any foreign materials in the combustion chamber or if it is dirty. Make sure that the heat exchanger is clean and not broken too.
19Error code 19 is a grounding error, or short circuit in the tankless water heater.It could be in the wiring harness, bypass valve, water flow control or another component within the circuit board. Visually inspect all components, look for exposed wires or damaged electrical components that could be earthing out.
25Error code 25 often means that your condensate pipe is blocked.Turn off your hot water system, Locate your system’s condensate line and visually inspect the pipe for blockages and clear them if needed. Check the condensate trap also. In very cold weather where it could be caused by something as simple as an iced-up pipe.
30 (Also error code FE)Error code 30 means that there are flammable vapors in the air. The vapor sensor may be damaged or have a loose wire, this would also cause an error code 30.Error code 30 is a fire hazard. Turn off the gas supply as you need to be sure no flame is present before you search for the problem. Inspect flammable vapor sensor for damage and loose wiring, if there is no visible damage then it may be time for someone qualified to do some further investigation.
31Error 31 on a Rinnai hot water system means that the burner thermocouple unit is faulty. The thermocouple unit measures the temperature of the water in the hot water system.This isn't an easy fix so we suggest you leave this one to the professionals. But if you want to give it a go, first, check the fire manifold pressure settings to make sure they are set at the right level. Secondly, you need to check that all of the dip switches are set in the correct position on the unit's PC board. And finally, you need to check for a milli-volt reading on your thermocouple to make sure it is in range.
32A number 32 error code on your Rinnai hot water system means that the water temperature sensor is not working. This could be because of faulty wiring or because it has been damaged.Make sure the temperature sensor is clean and in good working condition. Look for any limescale deposits on it. Check its resistance and wiring for visible damage, too. If the problem still exists, replace the sensor!
33When you get error code 33, you may not be able to get hot water out of your faucet. This is because the sensor that controls how much gas should flow through it has malfunctioned. The sensor on the heat exchanger will stop all gas from flowing into your water heater, so it only produces cold water.To fix error code 33, you need to check that the sensor and wire are in working order. Clean any dust or dirt off of it if there is some buildup. Check the resistance of the sensor. If this does not work, replace the sensor with a new one!
34The Rinnai error code 34 means that there is a problem with the combustion air temperature sensor and indicates abnormal combustion is taking place. Your unit will shut down automatically as a safety precaution.The sensor should be checked to see if there is anything that may stop it from working. Check for scale build-up, and loose connections to the sensor. Also, remove any dirt or objects near the vent terminal and unit which might restrict airflow or block airflow entirely. If this fails, then replace the sensor.
35Rinnai error code 35 is when there is a problem with the tank's temperature sensor.Look for any places where the sensor might have a faulty connection. Clean off anything that might have built up and try to test the sensor. If it still doesn't work, replace it.
38Rinnai error code 38 means that there is something wrong with the exhaust thermistor or CO sensor.In addition to checking the sensor, check for loose wires and buildup. If there is any, clean the sensor. When needed, replace the sensor or PC board. Also, make sure that your gas inlet supply is according to specifications and make sure the low and high fire pressure are set up correctly. Check if you have a venting system that has been properly installed.
41Rinnai error code 41 means that there is an issue with protecting your hot water system from freezing. It can cause the pipes to break and fragile metal and plastic parts inside the system to become more brittle.Make sure the sensor is working and plugged in. If it is outside, cover it so that it measures the inside temperature, and not the outside ambient temperature. Replace if faulty.
51If your error code is 51, it means that there is a problem with the system's water inlet sensor. If the sensor isn't working properly, it can affect how hot the water on your hot water heater stays. The unit won't be able to regulate or control the temperature of the water.Check and fix any broken wires. Clear any obstructions, then replace the sensor if there still isn't a reading on it.
52A code 52 means something is wrong with the gas modulating valve.If you have a code 52, make sure that the terminals are not damaged or loose on your wiring harness. You need to measure the resistance and voltage of your valve making sure they're up to manufacturer's specs. If all readings come out good but your code 52 continues to show up then it may be time for a replacement PCB board.
57A Rinnai error code 57 might mean that the burner's bimetal switches is overheated, or that the gas pressure is wrong. Another thing that could make it happen is if the sensor is faulty and needs to be replaced.The Rinnai error code 57 can be caused by a variety of factors. If your gas pressure is too high or the wrong type, you might have an issue causing the heater to burn too hot. Sometimes it happens because of wiring issues so check for obvious damage.
58Error Code 58 on your Rinnai water heater indicates a secondary heat exchanger sensor fault. One of the two bi-metal plates may be open.If your heat exchanger is dirty, or there is a build-up of limescale it could cause this problem. Fix the problem by cleaning and flushing the heat exchanger. It might also be a wiring problem too, so if you know how to check the wires then you can do that yourself. If not, then contact a certified technician for help.
61Error Code 61 means that there is a problem with the combustion fan motor in your Rinnai water heater.Check how freely the fan moves, it should turn without a problem, if it is tight first make sure there isn't anything else in the way of moving the fan. If not you may be able to clean it and get it moving freely again. If it moves freely then check if there are any wires that need to be fixed. Replace the fan if needs be.
63If your Rinnai has an error code 63, it means that the circulation Flow Rate is less than 1.3 GPM.You can use the temperature controller on your Rinnai tankless water heater to check how much water is coming out of it. Press the "UP" button for 3 seconds, then press the "ON/OFF" button.
The number on the screen will tell you how much water is coming out of your tankless water heater. If it does not come out at least 1.3 gallons per minute, (displayed as 13) bleed air from your pump and system tank and clean your inlet filter.
Rinnai hot water heaters require a high input flow rate or they will not work properly so make sure that there are 6 gallons per minute flowing into it.
Make sure that the inlet water pressure to the tankless water heater is 30 to 50 psi.
65The Rinnai fault code 65 error relates to the "bath fill" function and means that there is a water flow control fault. Water may not be stopped correctly during the bath fill function for some reason.You can attempt to clear this error quite simply, The first thing you need to do is turn your hot water tap off, then back on again. Next, turn the control monitor off before turning it back on- this will reset any errors that may have been caused by power interruptions during the fill function. If the fault code still appears, you will need to call in a technician to fix the issue.
FE (Also error code 30)Error code FE means that there are flammable vapors in the air. The vapor sensor may be damaged or have a loose wire, this would also cause an error code FE.Error code FE is a fire hazard. Turn off the gas supply as you need to be sure no flame is present before you search for the problem. Inspect flammable vapor sensor for damage and loose wiring, if there is no visible damage then it may be time for someone qualified to do some further investigation.
FFA code FF, is used to show that maintenance or a repair has been performed.You do not need to do anything if you see this code. It is used for diagnostics and making it easy to find out if an error happened after the service was done. To make use of this code you can do so by pressing the up, down, on, and off buttons simultaneously.
70The Rinnai error code 70 means that you have a problem with the circuit board.You will need to inspect the condition of the PC board switches and connection harnesses. In most cases though, replacing the PC board will be the only solution.

Rinnai's old models used error code 70 to show that the ON/OFF switch was faulty. Some of these switches were repaired, but in most cases it had to be replaced entirely.
71An error code 71 means that one of the 4 solenoid valves has failed.Often, Rinnai error code 71 means that you need to change the PC board. However, occasionally the error can be caused by moisture inside the gas valve. If this is the case, you may need to replace it. Inspect the voltage reading and the resistance of the solenoid valves and make sure that there are no bad readings or moisture build up. Replacing anything with a fault.
72Rinnai error code 72 means that there is a problem with your flame sensor. When the sensor sees that the flame is not working, it will turn off the gas to your hot water heater to keep you safe.Sometimes the Rinnai error code 72 happens when there is something blocking the flame rod and a build-up on it. You need to check if the wiring is set up right and it is a good idea to check the microamp output of the rod if you have the tools to do so.

Sometimes something inside the burner can make it short circuit. This error code happens when that happens.

If the flame rod is broken, you will need to replace it. If the flame rod gasket is broken, you will need to replace that too. You might also need to replace the PC board.
73The Rinnai error code 73 indicates a problem with the burner thermocouple in the hot water unit.Make sure that the thermocouple is in good condition and not loose. The dip switch should also be set up correctly. If these steps don't seem to fix it, try replacing the thermocouple or PC board for a new one!
79Error code 79 means that the sensor has detected a water leak.A leak sensor is like a detective in the water heater. If there is any water leakage, it will tell you. Make sure that the sensor and piping are in good condition and not damaged or loose, then dry off any water inside the unit and restart it. If there are no signs of leakage but the code displays again, try disconnecting the leak sensors to see if your water heater will work without them. Monitor closely for any sign of leakage with or without a sensor connected to make sure it works correctly either way before replacing anything.
LC, LC0 - LC9These errors show when there is a build-up of scale in the heat exchanger. The heat exchanger needs to be flushed so that damage does not occur.If your tankless water heater displays an LC code, it will most likely not be stop working. But, the controller will beep at you and you should flush the tankless as soon as possible to prevent damage. Refer to your manual for directions on how to do this.

How To Reset Rinnai Tankless Water 

How To Reset Rinnai Tankless Water

Resetting of Rinnai can be done in more than one way. We would let you know a quick and detailed procedure for this purpose. Let us begin to explore it.

Quick Rinnai Tankless Water Heater Reset Procedure

  • Drain the tankless water heater heat exchanger.
  • Switch off the warm water tap.
  • Push the off and on buttons two times.
  • Switch on the hot water tap and check its flow. If the tap gives you warm water, you have successfully reset your tankless water heater.
  • If it did not work the first time then you need to follow this process a few times.
  • After repeating this procedure, the problem should be fixed.
  • If the tankless water heater is still not working then you will ned to do some further investigation into the error code and what is causing it.

Fixing with reset buttons

Sometimes a simple reset does not bring the desired results. Thankfully, Rinnai tankless heaters have built-in error code buttons for specific problems.

Error code 63 fixing

  • Check the flow of water with the help of a temperature controller.
  • Long press the “UP” button.
  • In the very next step, push the “ON/OFF” button.
  • For the flow rate of fewer than 1.3 gallons per minute, there is a need to expel the air from its system and pump.
  • Detach the inlet filter and clean it perfectly.

Error code 10 fixing

  • To fix error code 10, a good practice is to check the venting material. If Rinnai does not approve the material, immediately replace it with a good alternative. You can get the favor of an expert if you have zero knowledge about replacement.
  • In the very next step, check the exhaust and inlet of fuel.
  • Check all the venting connections. If they are not properly connected, make them perfect.
  • Check the correct installation of the condensation controller. It should be properly installed and not loose.
  • Now, check the working of a fan, but it should be accurate.
  • The dip switch should be in good condition.
  • After checking all these parts, you may get the services of an expert if code 10 persists.

Leakage issue

Rinnai tankless water heaters produce a sound to warn you about internal leakage. In addition to water leakage, it lets you know about gas leakage and less fuel.

Maintenance of Rinnai heater

Typically, a gas water heater requires very little maintenance, but if you give it a quick service two times a year it will last you a long time without giving you any problems. Gas heaters like Rinnai need more regular servicing than electric heaters as they rely on a clean ignition and burn to work effectively.

Advantages of Rinnai Tankless Water Heater

Like other models of heaters, Rinnai comes with multiple advantages. Some common highlights are as follows

  • Rinnai comes with an error code feature for good control over the system
  • It is integrated with multiple safety features that give you peace of mind.
  • It uses natural gas or propane as fuel which is far more efficient and cheaper than an electric water heater.
  • The excellent control panel makes it super easy to set your hot water temperature according to your requirements.
  • Rinnai instant tankless water heaters give you excellent flow rate that is better than multiple other brands, making them ideal for large families.
  • It can work equally well in a place with low groundwater temperature.

Disadvantages of a Rinnai Tankless Water Heater

  • Every technology comes with some limitations. In the case of Rinnai, the most common cons are as follows;
  • The size is very large, and the weight is heavy, which makes it less portable.
  • All units of Rinnai are built either for indoor or outdoor installation. No unit comes with technology for both types of installation.
  • Rinnai heaters are a premium product so some people cannot afford them, even thought they are cheaper in the long run.
  • You can’t use Rinnai for RV water heaters.
  • You need a wider place for its installation.
  • Rinnai requires professional installation to avoid voiding the warranty adding to the initial cost.
Frequently Asked Questions ( FAQs )

1. How to maintain a Rinnai tankless water heater

Over time, a tankless water heater may accumulate mineral build-up which can erode the walls inside your tank’s heating chamber. To properly maintain and clean your tankless water heater, it’s important to flush those mineral deposits at least once a year. Follow this simple process to ensure optimal tankless water heater performance and efficiency.

Close (turn off) the three water valves attached to your tankless water heater. This prevents cold water from flowing into the water heater and hot water from coming out during the cleaning process.

The water valves consist of a cold water valve (colored blue), a hot water valve (colored red) and a main valve that runs the water into your home. Remove the purge port valve caps slowly from the purge valves located on each of the cold and hot water valves.

This procedure is done to relieve any pressure that has built inside the valves and will prevent excess hot water from shooting out during the cleaning process. There may be pressure when removing the purge port valve caps, so it’s vital to confirm the hot water valve is completely shut off for your safety.

If the supplier of your Rinnai tankless water heater did not provide hosing lines, they are available at any home repair store that sells water heaters. Consult the manual provided by Rinnai or contact the manufacturer directly for exact instructions regarding this procedure. In some cases, this procedure may require you to use a sump pump and connect hoses to discharge and flush water from the tankless water heater cold and hot water valves.

The best way to maintain a Rinnai tankless water heater is to fill a large bucket with 4 gallons of undiluted white vinegar. Use a recirculating pump to flush the vinegar through the system every 6 months. This solution will help remove scale and grime that may have built up in the system. Do this if you want the unit to work more efficiently and longer. Since your home’s drinking and bathing water mostly likely flows through your tankless water heater, using chemical cleaning solutions could be extremely harmful to your health, so only use white cleaning vinegar.

Once the flushing process is complete, close the purge port valves by twisting the T-shaped handles. Refer to the manufacturer’s manual for exact instructions on how to safely restart your water heater. This may require you to rotate and open the cold and hot water valves so they are parallel to the position of the main valve.

This method of flushing the unit is simple and should take around 45 minutes to completely clean and flush your Rinnai Tankless Water Heater.

2. What does the priority button light show in Rinnai?

Typically, the temperature controller comes with a priority button is Rinnai. The Greenlight is a clear indication that temperature is being monitored. When the system shows this color, it means that hot water is available to use.

Plus, the absence of green color tells no hot water is present.

3. What does code 12 mean in Rinnai?

Code 12 in troubleshooting shows that Rinnai is suffering from the low gas flow. Moreover, it is also an indication of flame failure issues. To fix this issue, You are needed to check the meter of gas. Make sure to clear this area if obstructed.

4. What does code 11 indicate in the Rinnai tankless water heater?

Error code 11 in Rinnai shows that the system lacks ignition. Plus, it may show that your heater is receiving zero gas supply. To fix this issue, check if your system has some damage. The gas supply should be switched on for successful troubleshooting.

5. What are the advantages of a tankless water heater?

Tankless Water Heater comes with multiple advantages over a storage hot water system. The most main advantages are that Tankless Water Heaters provide ample hot water in less time, hence why they are often referred to as “instant Hot water systems”.

You do not need to wait for long to use warm water due to its advanced technology. Its size is compact and portable that allows easy installation. It is an energy-efficient product. This type of heater only starts to heat water when you turn the faucet on. In this way, no loss of energy occurs. It comes with an LED screen that gives good control over temperature.


If you already own a Rinnai, then it is likely that you have relied on the quality of these appliances for years. But being one of the top brands does not mean that there will never be any problems with your tankless heater.

If you are diligent about servicing and following error code guides to fix issues, you will have many years of quality instant hot water enjoyment! After all error fixes or maintenance work has been completed just remember, follow our instructions on How to reset Rinnai tankless water afterward.

Moreover, all these steps are simple to follow but need good insight. So, whether you are a beginner or expert, you can give resetting your Rinnai water heater a go, and it might just save you quite a bit of money.

Every tankless water heater may suffer from small issues during routine use. But don’t worry, I am sure that you are smart enough to deal with all these issues yourself now.