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Most Common Problems With Tankless Water Heaters

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What Are the Most Common Problems With Tankless Water Heaters?

As advanced and convenient as they are, all tankless water heaters are susceptible to problems as they experience wear and tear. No appliance is without the risk of fault throughout its lifetime. Unlike traditional tank water heaters, tankless water heaters come with their own set of common problems.

Tankless water heaters offer excellent energy efficiency, space-saving in the property, and the potential to save money. Those benefits can be undermined by certain issues, however, so it’s important to understand what common problems are and how to avoid or resolve them.


Every tankless water heater has a flow rate capacity that should give you a good idea of how much hot water can be used simultaneously. If you go over that capacity, then you could overload the system and cause problems. This is a common issue because many homeowners don’t realize that tankless water heaters have limitations for simultaneous hot water usage.

If your tankless water heater is overloaded, then you might find that some of the users are getting hot water and others aren’t. In some cases, a system overload can lead to the heater shutting down entirely.

The best way to prevent a system overload is to understand your heater’s capacity and how many different appliances can use it at the same time. If you’re running into a consistent issue, however, call a professional. You may need to consider upgrading your heater or even getting a second heater to make up the deficit.

Cold Water Sandwich Effect

You may not be familiar with the term “cold water sandwich”, but if you live in a home where back-to-back showers are frequent, you will likely be familiar with the sensation.

A cold water sandwich is when one person finishes showering and another person gets in right after. The water starts off hot but soon turns cold for a few seconds up to a minute before starting to heat up again.

This happens because when the shower is turned off, the water is no longer heated, but there’s still some hot water in the pipes. This hot water comes out first before the cold water follows. The tankless water heater will be working to get the water heated back to a normal temperature, so it shouldn’t be cold for too long.

This effect isn’t so much an issue with your heater as it is part of its design. While tankless heaters are known for quick heat times, the fact that hot water cannot be stored makes it impossible for the system to ensure hot water immediately after it has been turned off and turned on again.

However, if you notice that these cold spells during your shower are longer than a minute or so, you may be experiencing other issues, and it would be wisest to consult a professional.

Mineral or Sediment Buildup

The water heater and the pipes could be susceptible to becoming blocked partially or fully due to a buildup of minerals or sediment. Systems with iron pipes and components can rust and lead to iron sediment building up throughout. Meanwhile, homes with hard water could see minerals like calcium and magnesium resulting in a scale buildup.

Over time, these minerals and sediment can become stuck in place, leading to a gradually growing buildup that narrows the passage that the water moves through. This can affect the pressure and temperature of the water and make it potentially unsafe.

If you are experiencing problems relative to buildup, you’ll need to call a professional to flush your system. This should be a part of your regular annual maintenance so as to avoid more damaging issues caused by mineral or sediment buildup.

Flame or Ignition Failure

"My tankless water heater doesn't get hot enough". This may be a question you are asking, it could be that the flame fails to hold or ignite, then it is likely due to an electrical issue or a gas line issue. Either way, your heater will be unable to heat the water. First, check to see if your propane tank is low or if your gas supply has been cut due to a late bill.

If your gas supply is fine, see that your water and gas valves are fully open, and open them if they aren’t. If this doesn’t help, then you should get in touch with a professional who is qualified to work safely with gas appliances, as the issue could be anything from regulator failure to an undersized gas line and could pose dangers to your home.

Call The Water Heater Company Today

Dealing with hot water appliances can be dangerous, so if you’re uncomfortable with any step of troubleshooting or maintaining your tankless water heater, contact a professional right away. Our experts at The Water Heater Company can safely handle any issues you’re experiencing and offer you the right tankless water heater services for your needs.

Contact the professionals at The Water Heater Company at (877) 274-1485. Call today to schedule an appointment or to learn more about the most common problems with tankless water heaters.

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