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Common Tankless Water Heater Problems and How to Fix Them

You've replaced your traditional water heater with a tankless water heater. It's much more efficient, and there's always hot water. Problems with the tank can still arise, and it's important to know when you should call an HVAC company to help fix it. Let's talk about some common tankless water heater problems and how to fix them.

Tankless Water Heater

First, let's talk about what a tankless water heater is. It's just as it sounds. It can heat water without needing a storage tank. It uses a gas burner or an electric element to warm the water as it passes through the unit. That means it only will heat the water when you need it. Tankless water heaters can last longer than traditional water heaters. Even though they last longer, issues can still arise.

Common Issues

All appliances are subject to fail and have problems no matter how good they are. Sometimes common issues will happen that you may be able to solve on your own.

Mineral Buildup

Calcium and Magnesium can build up in the tank and impair how it works. This can reduce how long a tankless water heater can last. You can often use vinegar or a specialized descaling kit to flush the tankless water heater. If hard water is the issue causing the buildup, then you can install a water softener.

A Cold Water Sandwich

This happens when hot water is left in the pipes. When you turn on the water, first hot water will come out, but then it's followed by cold. It takes a moment for it to heat back up, and when it does, it'll get hot again: hot on each side and cold in the middle. Tankless water heaters still need time to heat up, so the cold you feel is a gap in the timing. There is no prevention for this besides waiting until the water heats up.

Flame or Ignition Failure

A sign that this is occurring is that you won't have much or any hot water. There are a few things that could cause this failure. Rule out easy causes first. Is your propane tank full? Are your valves fully open? If you fail to solve this issue, it's best to contact an HVAC service.


The tankless water heater's capacity can overload if too much water is running at the same time. Overload can happen if multiple hot water sources are running. It could have a hard time providing hot water or shut down. To fix this, try not to use water when something else is using it. If this problem persists, it may be wise to upgrade to a larger capacity.

Many Benefits

Problems can occur with any appliance. The benefits of a tankless water heater are great. Water will only heat when it's needed, so it saves money. Not having to store and continuously reheat water can save energy costs. You'll get instant hot water, and you're not limited to the amount that's in a traditional tank.

Solving Common Problems

As you can see, a tankless water heater can have problems that may be solved with troubleshooting. If you're unable to troubleshoot, you may have to contact your local HVAC company. If you need a reliable tankless water heater professional in Kitchener, Waterloo, Guelph, Cambridge, Stratford, Woodstock, or surrounding areas, call Aire One Heating and Cooling, and they will resolve your tankless water heater problems. They provide many services and can assist you with all your needs.


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