why is tankless water heater beeping

8 Reasons Why Your Water Heater is Beeping & How to Fix it!

Is your water heater beeping? Whether it’s a tank or tankless, the beeping issue is pretty common but frustrating as well, especially when you don’t know the cause. Wondering why it’s doing that? Let’s find out and fix it for good.

The most common reasons for the water heater to beep include scale buildup, water or gas leakage, component failure, blocked air filter or vent, and many more. 

It doesn’t matter whether it’s gas or electric, Rheem, AO Smith, Rinnai, or else. All have this beeping mechanism – they call it an alert system to make the homeowner aware that there’s something wrong with the appliance. Usually, it can be not so big of an issue or even a fails alert but sometimes it can also be a serious matter like a gas leak. Fortunately, they also mostly show error codes that can be interpreted with the help of the owner’s manual. 

In this today’s guide below, we are going to discuss what are the most common issues that can cause your water heater to make that beeping noise and how to fix it. So let’s get straight into it.

The 8 possible reasons your tank or tankless water heater is beeping and how to stop it

1. Your water heater needs descaling

Water is always stored or passed through (in the case of tankless) the water heater. This very water contains elements like calcium and magnesium which are damaging to the metal components like the heat exchangers. 

If the water coming to your home is hard ( meaning the presence of a high percentage of the mentioned elements) then over time, these particles start to stack up and degrade water heating efficiency.

The most common error code the water heater shows, in this case, is “LC” but it can vary based on brand. In this case, the unit requires flushing and descaling of the sediments. You can either use this guide over here to flush the water heater yourself or call a plumber to do it for you. 

2. Leakage: Either water, gas or it’s just a faulty sensor


Another common cause for a water heater to beep is leakage. It can be either water or gas leakage. A modern water heater comes with a leakage sensor to protect your property from water damage. 

If you see water puddling near or under your tank or tankless water heater or inside the casing of the tankless unit then you have found the culprit. Now based on the source of leakage, you will have to come up with a fix. But dry the unit first and see if it stops the beep for good. You will want to contact your manufacturer if your model is under warranty. Here’s what to do when the water heater leaks.

For gas-fired models, if you are sensing the rotten eggs smell then there is a gas leak. Shut off the gas supply and call the gas company immediately. If your tankless water heater is leaking from the bottom then refer to this detailed guide.

3. It’s also possible that the air intake or vent channel is blocked

When this happens, the tankless water heater beeps code 10 but again it can vary based on the heater make. 

A gas-fired water heater requires a fresh oxygen supply for combustion. When this air intake filter or combustion fan is choked or blocked due to a variety of reasons, the burner suffocates and can’t ignite. Similarly, if the vent is blocked then flue gas can’t get out of the system thus triggering that “beeping”. Check and clean the filter or vent.

4. Overheating warning

overheating warning

Sometimes what can go wrong is the heating elements. A malfunctioning heating element or temperature sensor can overheat the water. Scalding hot water can burn your skin. Fortunately, most of the time your tank or tankless water heater will show up with the error code along with a beep. 

Different brands have different codes. I advise you to refer to your owner’s manual or check the manufacturer’s website for code and contact a professional to fix it. 

5. System overload in case of tankless water heater

System overload in case of tankless water heater

Tankless water heaters have limitations to how much hot water they can supply per minute. That’s why sizing properly is important and I have written a complete guide on that here

If you cross this limit by opening multiple hot water fixtures then usually either water temperature or flow drops. But some models can even make a beeping sound. 

Close all taps and see if the beep stops. 

6. Low inlet supply or clogged inlet or aerator

Remember that scale build-up we talked about in point one? That scale can block and clog your incoming line which can reduce cold water flow to the tankless water heater and when there’s not enough hot water coming to the heat exchanger then there’s a chance of water overheating. And so the water heater alerts with a beep. 

But how do you know that’s the case? Have you noticed a low amount of water coming out from your fixtures or perhaps hotter than set water is coming? You have got a blockage. 

7. Maybe your water heater is low on fuel

This case only applies to propane-fired tankless water heaters. Some make of propane heaters give out a beeping alert when fuel is about to run out as the fuel pressure drops. 

8. Excessive water pressure

There come some times when the pressure of water coming to your home suddenly shoots up. There’s a limit to how much maximum pressure a tankless water heater can operate at. 

High pressure can be damaging to water heaters. So when such an incident occurs most tankless water heater gives out a beeping alert.

Fixing Rinnai tankless water heater beeping code 79

fixing water heater beeping

The error code 79 on the Rinnai tankless water heater refers to the internal leakage. Check for any water spill on the floor. If it’s dry then open the front panel of the tankless water heater. Make sure to shut off the supply before that. 

See if there’s any moisture inside. Carefully dry it out and the beep should be gone. 

If the beeping triggers again and leaks then call the plumber or manufacturer if it’s still under warranty.

Your call!

So that’s it for now. I hope it helped you fix that frustrating beeping alert off your water heater. If nothing mentioned above works out then the best will be to get the help of a professional. What’s next? If your water heater is going cold after a few minutes then here is probably why.

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