Hot Water Heater Is Only Lukewarm [Causes and How to Fix]

A common issue with hot water heaters is that they only produce lukewarm water. What causes this? What is the main reason why a hot water heater is only lukewarm?

If the water coming out of your hot water heater is lukewarm, the likely cause is sediment buildup in the water heater tank. While the water sits in and is successfully heated, the debris settles to the tank’s bottom. This buildup makes the heater less effective in heating water, which then results in lukewarm water.

There are several other possible reasons why your hot water heater only dispenses lukewarm water. These include the following:

  1. Your Gas Water Heater Runs out of Gas
  2. Broken Dip Tube
  3. Safety Shutoff
  4. Clogged Pipe
  5. Broken Thermostat
  6. Problem with the Immersion Heater
  7. Tripped Breaker

Read on to learn more about why hot water heaters only produce lukewarm water and how you can fix this issue.

Hot Water Heater Is Only Lukewarm

hot water heater only lukewarm

If your hot water heater produces lukewarm water, there maybe is a sediment buildup in the water heater tank. While the water sits in and is successfully heated, the debris settles to the tank’s bottom. This buildup makes the heater less effective in heating water, which then results in lukewarm water.

Possible Causes of Lukewarm Water from Water Heater

1. Sediment Buildup in the Tank

The water that goes through the heater tank contains small amounts of sand, dissolved minerals, and other debris. These particles settle to the bottom, preventing the heater from doing its job efficiently.

2. Your Gas Water Heater Runs out of Gas

If you turn off the gas to your home, your gas water heater will shut off too. This will allow the temperature of the water inside your heater to slow down gradually.

So, when your heater produces lukewarm water, check first if you still have a gas supply. If yes, make sure that your water heater also has enough gas supply. Then, turn it on. The pilot light of your heater is the indication of whether there is a gas supply or none.

3. Broken Dip Tube

If your heater produces lukewarm water, it could be because of a broken dip tube. A dip tube is a piece of tube attached inside the heater. It directs the cold water in the tank from the top and down to the bottom, where it gets heated.

A damaged dip tube will fail to direct the water to the bottom of the tank. Some may go directly to the tank’s heating facility, but some, or most, might not. This then produced lukewarm water.

In some cases, you can still replace a broken dip tube. But more often than not, it is not worth replacing anymore. Sad to say, once it is broken, you might already have to replace your entire water heater.

4. Safety Shutoff

Water heaters have a safety shutoff feature. Your heater will automatically shut off in case the unit itself becomes too hot.

This feature is integrated into heaters for the safety of users too. When this feature shuts off, there is generally no way to turn it back on unless you know how to troubleshoot or repair it on your own. But, in most cases, when your unit shuts off, the entire part has to be replaced or removed.

5. Clogged Pipe

There are times when the problem doesn’t have anything to do with the heater unit itself. Instead, the problem may be caused by a clogged pipe. When this happens, hot water is prevented from passing through the faucet.

Try to observe if all other faucets produce hot water except for one particular faucet. If this is the case, then the problem most likely concerns a clogged pipe.

To fix this issue, you need the help of a plumber. The plumber can help you identify which part of the pipe is clogged. Once identified, the plumber will advise you whether the pipe needs replacement or it simply needs cleaning.

Once this is fixed, hot water is expected to be able to successfully come out of the faucet.

6. Broken Thermostat

The reason why your hot water heater only produces lukewarm water may be because of a broken thermostat.

To confirm that this is the problem, turn the temperature of your heater to a high setting. This is expected to make the gas burner kick on. In case it doesn’t, this is the indication that there is a problem with the thermostat.

This typically happens when your water heater is already a decade old or more. Such a problem also happens if you don’t follow the recommended maintenance schedule for your water heater. Typically, it needs flushing on an annual basis. Otherwise, its lifespan may only be less than 10 years.

7. Problem with the Immersion Heater

In most cases, there are two immersion heaters inside the cylinder. If one of these immersion heaters malfunctions, water will not be completely heated. So, this can be a reason why your heater produces lukewarm water.

The other immersion heater, which is fully functioning, will continue to heat the water. But then, it will not be able to produce enough hot water for an entire household.

8. Tripped Breaker

Again, there are times when the problem is not the hot water heater itself. So, it’s best to check all other possibilities. One of which is the breaker. A tripped breaker may be causing your hot water heater to stop working. This may be the cause of having a lukewarm hot water heater.

To have this fixed, return the breaker switch to its position. Then, check if the heater has started to function properly and has started to produce hot water.

How to Fix the Lukewarm Water Issue of Your Hot Water Heater

hot water heater is only lukewarm

By now, you already know that there are different reasons behind the lukewarm water produced by your hot water heater. The most common of all is the sediment buildup in your heater’s tank.

If your hot water heater produces lukewarm water, there maybe is a sediment buildup in the water heater tank. While the water sits in and is successfully heated, the debris settles to the tank’s bottom. This buildup makes the heater less effective in heating water, which then results in lukewarm water.

But, to reiterate, there are other possible reasons why your hot water heater produces lukewarm water. These include the following:

  1. Your Gas Water Heater Runs out of Gas
  2. Broken Dip Tube
  3. Safety Shutoff
  4. Clogged Pipe
  5. Broken Thermostat
  6. Problem with the Immersion Heater
  7. Tripped Breaker

So, once you have successfully identified the root cause of the problem, your next step is to determine if you can still repair your water. If it’s beyond repair, then there’s no other choice but to have it replaced.

Thermostat Issue

In case the issue is with the thermostat, it is possible that you can have it replaced all by yourself. All you have to do is to find the right replacement.

Also, make sure that you get to identify which thermostat has an issue successfully. This way, you can ensure that you are replacing the correct one.

Tripped Breaker Issue

If the issue is a tripped breaker, you can simply flip back the breaker to its original position. Hopefully, this is the only issue you encounter so that no repairs or replacement will occur.

Dip Tube Issue

If the issue involves the dip tube, the best way to resolve this is to seek professional help from a trusted plumber. In most cases, a dip tube issue needs the replacement of the entire heater tank.

The dip tube is located inside your water heater unit that is somewhat impossible to reach. It is best to replace the entire tank to fix the issue. Forcing to replace the dip tube alone might cause damage to other parts of the heater. Suffice it to say that even if you have successfully replaced the dip tube, your heater might still not work since the other parts have also been broken.

Mineral Buildup Issue

To resolve this issue, you need to seek help from a professional plumber. The area where the minerals build up is somewhat hard to reach. It will be a challenge for you to reach the spot. If you force yourself to do it, you might end up damaging other parts of the heater. This might cause you further problems.

Once it is fixed, you might want to consider using chemical agents against mineral deposits. You can apply it to avoid mineral accumulation in the future.

How to Avoid the Lukewarm Water Issue of Your Hot Water Heater

lukewarm hot water heater

You can prevent your hot water heater from malfunctioning and producing lukewarm water. But, honestly, there are only a few things you can do to avoid it:

  1. As for the thermostat, what you can do is regularly check the thermostat temperature. That way, you would know if it is still running smoothly or not.
  2. When it comes to the pipes, make sure to clean them regularly. Use chemical agents to clean them to eliminate minerals and bacteria. In case you are not aware, the water moving through the pipes accumulates bacteria and minerals. Clogging then prevents the heater from functioning well.
  3. It is best to heat an adequate amount of water only. Having excess water means you will leave warm water inside the cylinder. This will cause you to have warm water in the tank for several days.

It is quite frustrating to have a broken hot water heater, especially during cold seasons. But this is a problem in every household. A hot water heater is tough to maintain. In most cases, if your hot water heater breaks down, you will need to hire professional plumbing help.

So, it is always recommended to find time to have your hot water heater undergo maintenance service regularly. That way, you will prevent it from suddenly breaking down.

Conclusion – Hot Water Heater Only Lukewarm

If the water coming out of your hot water heater is lukewarm, it most likely has a sediment buildup in the water heater tank. While the water sits in and is successfully heated, the debris settles to the tank’s bottom. This buildup makes the heater less effective in heating water, which then results in lukewarm water.

However, there are several other possible reasons why your hot water heater only dispenses lukewarm water. These include the following:

  1. Your Gas Water Heater Runs out of Gas
  2. Broken Dip Tube
  3. Safety Shutoff
  4. Clogged Pipe
  5. Broken Thermostat
  6. Problem with the Immersion Heater
  7. Tripped Breaker

Sometimes, we take our hot water heater for granted. We always think that it does not need any attention for as long as it is working fine. When in fact, it also needs care.

If it malfunctions, we can’t do much about it but seek professional plumbing assistance. But we can always do our part to prevent it from malfunctioning, especially if we want it to last for years.

If you have zero knowledge about plumbing, it is best to hire a plumber. Don’t try to fix it all by yourself. In case you have plumbing experience, you most probably know what to do with a malfunctioning water heater. But then again, when in doubt, there is always a professional plumber you can hire and help you address the issue.