Why Tankless Hot Water Heater Stopped Making Hot Water

Published On: May 22, 20230 Comments on Why Tankless Hot Water Heater Stopped Making Hot WaterTags: Last Updated: January 24, 20243.8 min read

While Rinnai tankless hot water heaters are generally reliable, there is one problem many homeowners face with them – they stop making hot water! This can be incredibly frustrating, especially if you’re used to having an endless supply of hot water at all times.

tankless water heater

There can be several reasons why your Rinnai tankless hot water heater is not making hot water, but we’ll cover the most common ones in this article so you can troubleshoot the issue and hopefully fix it yourself!

5 Possible Reasons for No Hot Water

1. Gas Supply Issue

One possible reason why is due to a gas supply issue. This can be caused by a malfunctioning gas valve or a disruption in the gas supply line. Check that your gas supply valve is turned on and that other gas appliances in your home are functioning properly. If they are

2. Ignition Failure

Another potential cause for no hot water from your Rinnai Tankless Hot Water Heater could be an ignition failure. If this is your issue your Rinnai will be displaying Error Code 11.

3. Blocked Venting System

A blocked venting system can also cause issues with your Rinnai Tankless Hot Water Heater. This occurs when there is an obstruction in the vent pipe or air intake pipe which prevents proper air flow through the system. In order to fix this issue, you will need to clear any blockages from these pipes or consider hiring a professional who can clean them out for you.

4. Dirty Air Filter

If you have not cleaned or replaced your air filter recently, this could also result in no hot water from your Rinnai Tankless Hot Water Heater. A dirty air filter restricts airflow through the system which then puts strain on its components and leads to malfunctions like no hot water output. Check your owner’s manual for instructions on how to clean or replace your unit’s air filter.

Scale Buildup in the Heat Exchanger

Scale buildup in the heat exchanger is a common issue that can prevent your Rinnai Tankless Hot Water Heater from producing hot water. This occurs when minerals in the water supply accumulate within the heat exchanger and restrict proper water flow. It is pretty easy to do yourself and this article explains it well: How to flush a rinnai tankless water heater.

flushing tankless water heater

Maintenance Tips to Prevent Future Issues

Regularly clean air filter and flush out scale buildup

To prevent your Rinnai Tankless Hot Water Heater from having future issues, it is crucial to maintain it properly. One of the things you can do yourself is regularly clean the air filter. The air filter protects the system’s components from dust and debris that can harm the unit’s efficiency. A clogged air filter will restrict airflow, which will cause your heater to work harder than it should and decrease its lifespan. Cleaning or replacing the air filter at least once every six months will go a long way in ensuring your heater works efficiently.

Another important maintenance tip is flushing out any accumulated scale buildup in the heat exchanger. The heat exchanger transfers heat from one medium to another, making it a crucial component of your tankless water heater. Hard water can cause minerals such as calcium and magnesium to build-up inside, reducing its efficiency over time. Flushing out scale buildup ensures that your unit operates at maximum efficiency.

Recap of Possible Reasons for No Hot Water and Troubleshooting Steps to Fix It

If you have the problem of a Rinnai Tankless Water Heater no hot water, there could be various reasons behind it. One of the most common reasons is a gas supply issue, followed by ignition failure and blocked venting systems. Dirty air filters and scale buildup in the heat exchanger are also possible culprits. To troubleshoot the problem, you can check the gas supply and pressure, reset the heater by turning it off and on again, clean or replace the air filter, or flush out any scale buildup in the heat exchanger.

If you’ve tried all these steps but still have no hot water, it’s best to call a professional for help. They can diagnose and fix any underlying issues that might require more technical knowledge or experience. Remember to maintain your Rinnai tankless hot water heater regularly to prevent future issues from occurring. Cleaning the air filter and flushing out any scale buildup can be done on your own.

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