Tankless Water Heater Goes Cold After a Few Minutes: How To Fix It?

Tankless water heaters are greater investments than traditional ones. These machines are highly efficient and easy to maintain.

Furthermore, they are real money savers as they only heat water on demand.

But yes, just like any other appliance, you will have some issues with it, such as a tankless water heater goes cold after a few minutes.

Don’t worry; in this article, we’ll discuss how to fix these problems smoothly. So without wasting much time, follow us to the end!

Tankless Water Heater Goes Cold – Why It Happens?

tankless water heater goes cold after a few minutes

When it is about warming up the water, a tankless heater will take more time. So, if you hurry and want to take a quick shower, things can get a little frustrating!

And after taking a long time to heat the water, when it gets cold in no time, anyone can get annoyed! But why this problem occurs?

Mostly it happens when there is a broken dip tube inside the water heater. Typically this issue occurs in old water heaters as the tube gets damaged over time.

If the tube gets harmed, the cold water gets mixed with hot water. As a result, you will get a freezing stream after a few minutes of enjoying a hot shower.

Now some of you may ask, what is a dip tube exactly? Well, it is a plastic pipe that sits insider your water heater. And the signs of a defective dip tube are:

  • Your water heater is an old one.
  • Your faucet aerators and showerheads are clogged.
  • Your water supply runs out fast.

How Do I Solve This Problem?

The most efficient way to solve this issue is to replace the old dip tube with a new one. For this task, you can hire a professional plumber or do it yourself if you are blessed with mechanical skills!

Once you install a new dip tube, your water will stay hot for longer hours so that you can enjoy your shower without any trouble. Now, watch this video to solve this problem and a lot of other common problems related to water heaters!

Some Tankless Water Heater Problems and How to Solve Them

Here are some common issues that you may face with your tankless water heater. And we will also tell you about the possible solutions so you can enjoy the benefits of this appliance to the fullest.

The problems we are going to discuss are:

  • No hot water
  • Water is too hot
  • Water isn’t hot enough
  • The burner doesn’t ignite
  • The burner is noisy
  • Low water pressure
  • Coldwater sandwich

No Hot Water

This is one of the most typical difficulties people have to go through when using a tankless water heater.

To fix this, you need to check the electricity, water and gas supply to the heater. And always ensure that the shut-off valve is open.

If these things are right in order, you can follow the instruction given below.

  • Inspect the gas burner, and flame rod creates sparks after turning on the unit or not. If they don’t, there is an ignition failure problem.
  • Make sure that the water flow is enough for heating the stream. And also, check for clogging in the pipe.
  • If the elements in the water pipe are frozen, there will be an interruption in the heating procedure. To prevent this issue, you can wrap your heater with an insulation jacket during cold weather.

Water Is Too Hot

If the temperature is excessive, the stream can burn you, and you don’t want that. So when this issue occurs, here are the things you need to do.

  • Firstly, check, is the temperature set too high? If so, you can reduce the heat to avoid unpleasant events.
  • When the water passage is clogged, only a little number of water will be heated, and it will be scorching hot! Hence, it would help if you kept the pipes clean all the time.
  • Always keep checking for mineral buildup and perform descaling once in a while. 
  • This problem may also occur when the output temperature sensor gets broken or damaged. You can replace this thing to solve this issue.

Water Is Not Hot Enough

tankless water heater

The water will not get the proper warmth due to many reasons. Here are some that might be causing this issue.

  • If the water temperature is set to low, the stream won’t get heated. So set the bar a little high to solve the problem.
  • Inspect the water filter and fixture aerator for clogging. Once you clear the buildup, the water will get proper heat.
  • Elements buildups inside the heat exchanger can cause this problem too. You can try descaling or flushing all the deposits to get a hot water stream.
  • When the gas valve fails to provide enough pressure, the stream won’t get enough energy to warm up. To fix this ordeal, it would be better if you get professional’s help.

Gas Burner Doesn’t Ignite

If the gas burner doesn’t ignite, there is no spark; you will not get enough hot water supply. In most cases, the stream will not warm up at all! So here’s what you can do to get out of that situation.

  • First of all, check if the water, gas and electricity is supplied to your tankless heater properly or not. When there is an interruption in these connections, the unit won’t work.
  • Inspect the flame rod’s wiring system. If there are any faults, you should replace the whole thing to be on the safe side.
  • When the gas control valve isn’t opened or if there’s a short circuit, the unit won’t warm up your water.
  • You can also check the venting system. If the air is bleeding from the gas line, that’s not good news!

The Burner Is Noisy

When the burner creates excessive noise, your shower sessions will become infuriating!

And to relax during that time, you should act on solving this problem as soon as possible.

  • When debris or any small object gets stuck in the heater’s fan, the unit can create irritating noise. Once you get rid of that, the heater will run quietly.
  • If there is a leak in the sealed combustion, you will go through this annoyance.
  • Unstable burner flames and low gas pressure can also create this issue.

Low Water Pressure

Sometimes low water pressure can occur due to the negligence of utility companies. If that’s not the issue, here’s what you can do.

  • Make sure that there is no problem with the water filter, fixture or plumbing.
  • The lowered gas pressure can also cause poor water flow.
  • When many faucets are running at the same time, you will suffer from this issue.

Cold Water Sandwich

The cold water sandwich is when you get warm water when you turn on the showerhead, the stream of cold water hits you in few minutes.

It is one of the most common problems with a tankless heater but don’t worry; there are some effective solutions.

  • Examine the plumbing system for fluctuation issues.
  • If the gas line isn’t sized properly, you are most likely to face this trouble. So you need to get it resized for a better experience.
  • Your heater will have this cold water sandwich issue when the venting pipe isn’t within limits.
  • If the water filter is clogged, clean it up to avoid this annoyance.
In Conclusion

In this article, we’ve covered all the typical issues that you may face after installing a tankless heater in your house or workplace.

So if your tankless water heater goes cold after a few minutes, you will know how to solve that problem without any struggle.

And remember, you can also take a professional’s help if things get too complicated. But with regular maintenance, most of the issues can be avoided pretty effortlessly!

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