Troubleshooting Tips for When Your Rinnai Tankless Water Heater’s In Use Light Is Not On

The Rinnai tankless water heater is not in use if the indicator light is off.

Rinnai Tankless Water Heater In Use Light Not On

A Rinnai Tankless Water Heater is a great way to stay warm and comfortable all year round–but if the “In Use” light isn’t on, then you may need to troubleshoot the issue. There could be several possible causes, such as a faulty igniter, air filter blockage, or water leakage. To diagnose and fix the problem, it’s important to inspect the water heater and its components. First, make sure that the pilot light is lit and that the thermostat is set correctly. Next, check for gas or water leaks and ensure that all of the valves are opened fully. Finally, clean any dirt or buildup on your air filter for optimal performance. If all these steps don’t solve the issue, you may need to contact a qualified technician for service.


A Rinnai tankless water heater is a great way to heat up water on demand. It is usually installed in a home or business and can provide hot water for many different purposes. However, if the In Use light on your Rinnai tankless water heater isnt turning on, there are a few different things that you should check before calling a repairman. In this article, we will discuss all of the possible causes and solutions for the Rinnai tankless water heater in use light not turning on.

Check Power Source

The first step to take when troubleshooting the Rinnai tankless water heater in use light not turning on is to make sure that the power source is connected correctly. Check that the unit itself has power by checking that the circuit breaker has not been tripped and that all of the connections from the power source to the unit are secure and intact. If everything looks good, then it could be an issue with either the power switch or some other component.

Check Pilot Light

If your pilot light has gone out, then this could be causing your in use light to not turn on. The pilot light is what ignites your burner assembly when you turn on your hot water tap. To check if your pilot light has gone out, locate it inside of your unit and look for a small blue flame if its not lit, then you will need to relight it following the instructions in your user manual.

Check Igniter

If you have checked both your power source and pilot light, and neither of them appears to be causing the issue, then it could be a problem with either your igniter or burner assembly. The igniter helps spark up combustion when you turn on your hot water tap so if its faulty then this could be preventing your in use light from turning on. To check this, find out where your igniter is located inside of the unit and inspect it for any signs of wear or damage if theres anything wrong with it then you should replace it as soon as possible.

Check Burner Assembly

Your burner assembly is what heats up the air inside of your unit so that hot water can be produced so if theres something wrong with this component then it could prevent your in use light from turning on too. To find out if this is causing an issue, open up your unit and take a look at all of its components if any of them look worn or damaged then they should be replaced as soon as possible.


In conclusion, if you find that your Rinnai tankless water heater in use light isn’t turning on then there are several potential causes that you should investigate before calling a repairman. Start by checking both the power source and pilot light before moving onto other components such as the igniter or burner assembly each of these components can cause issues with how well your unit functions so replacing any faulty parts is essential for ensuring optimal performance from your Rinnai tankless water heater!

Understanding the Problem

It is important to understand why the Rinnai tankless water heater in use light is not on. This could indicate a problem with the unit itself or could be a sign of an underlying issue. If the issue is not addressed, it can cause damage to the unit and possibly lead to water damage in your home.

Checking Connections

The first step in determining why the light is not on should be to check all connections and make sure they are secure. This can include checking that all power cords are securely plugged into their respective outlets. Additionally, make sure that any wiring connections for the unit are properly connected, as this could be causing an interruption of power flow or signal.

Testing the Unit

Once you have confirmed that all connections are secure, you can move on to testing the unit itself. Start by testing each component separately by turning it off and back on again. This will help determine if any part of the unit has a problem that needs to be addressed. If no problems are found with individual components, then it’s time to test the entire system as a whole by turning it on and off again several times.

Resetting Unit

If testing does not reveal any issues with individual components or with the system as a whole, then you may need to reset the unit itself in order to get it working again. To do so, first turn off power at the circuit breaker and wait for at least five minutes before turning it back on again. After doing this, you should reset any settings within the Rinnai tankless water heater control panel by selecting Reset from within its menu options.

Replacing Parts

If none of these steps has worked, then you may need to replace certain parts of your Rinnai tankless water heater in order for it to function properly again. Common parts that may need replacing include filters, hoses, thermocouples and other components related to gas flow or electricity supply. If you’re uncomfortable replacing these parts yourself, then call in a professional HVAC technician who has experience working with Rinnai tankless water heaters so they can help diagnose and repair any issues with your unit quickly and efficiently.

FAQ & Answers

Q: What is a Rinnai Tankless Water Heater?
A: A Rinnai Tankless Water Heater is a type of water heating system that provides hot water on demand. It does not require a storage tank, and instead heats water as it passes through an internal heat exchanger.

Q: What causes the In Use Light to not be on?
A: The In Use Light is typically controlled by the flow sensor, which senses when the flow of water has stopped. If the flow sensor fails, then the In Use Light may not come on. Additionally, if there is a break in the electrical connection between the heater and the light, then it may also not come on.

Q: How can I fix this issue?
A: To fix this issue, you should first check to make sure that there are no breaks in the electrical connection between your heater and the light. If there are no breaks in this connection, then you should try replacing or cleaning out your flow sensor to ensure it is functioning properly.

Q: Are there any other potential issues that could cause this issue?
A: Yes, there are other potential issues that could cause your In Use Light not to come on. These include faulty wiring or connections in your electrical system, an airlock blocking hot water flow, or a faulty thermostat or switch.

Q: Is it safe to use my Rinnai Tankless Water Heater without the In Use Light being on?
A: Yes, you can safely use your Rinnai Tankless Water Heater without having to worry about the In Use Light being on. However, if you notice any other issues with your heater such as low water pressure or an increase in energy bills then you should contact a qualified service technician for assistance.

Based on the information given, it appears that the Rinnai Tankless Water Heater is not working properly. The “in use” light is not on, which means that it is not receiving power and is unable to heat the water. This could be due to a faulty power connection or a faulty component within the heater itself. In either case, it would be advisable to have a qualified technician inspect and repair the unit if necessary.

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