Why Your Tankless Water Heater Is Not Always Hot

If you have a tankless water heater, you know how frustrating it can be to walk into your bathroom and find the hot water supply not working. This is especially true if you are in need of a hot shower or bath or want to wash dishes or do laundry.

According to statistics, it occurs in about 10% of all households, which works out to be about 1 out of every 10 houses. This is not surprising, considering that tankless water heaters have been around for only about 20 years. However, they have become quite popular with many homeowners because they offer several benefits over traditional storage-tank models.

So why are some people having problems with their new tankless units?

In this article, we will look at some of the most common reasons why your tankless water heater is not working properly and how you can fix them.

Signs Your Tankless Water Heater Not Hot Enough

According to the U.S. Department of Energy, more than 25% of all homes in the country are using tankless water heaters. But even though they’re so popular, many people aren’t sure how to tell if their tankless water heater is working properly.

So, if your tankless water heater isn’t hot enough, you’re not alone.

Here are some signs to look out for electric tankless water heater not getting hot enough:

Lukewarm water.

If you’ve been using your tankless water heater for a while and have noticed that the temperature of your hot water has been getting lukewarm, this could mean there’s something wrong with the heat exchanger. The heat exchanger is what heats up the cold water from your pipes before sending it through to the tankless water heater. If it’s not heating up properly, it won’t be able to heat the hot water either. 

Inconsistent water temperature. 

If you notice that the temperature of the water coming out of the faucet is inconsistent or changes rapidly from hot to cold, that’s another sign your tankless water heater isn’t performing as it should.

Water pressure problems. 

If you notice that your water pressure has decreased or stopped entirely after installing a new tankless water heater, this may be caused by an issue with your existing plumbing system—but it could also be caused by a problem with your new tankless model!

Prolonged time to reach hot water.

If the water from your tankless hot water heater is taking a long time to get hot, there may be an issue with your unit. The longer it takes for the temperature to change, the more likely it is that something is wrong with your tankless water heater rather than in the pipes or radiators themselves (which would cause an immediate drop in pressure).

Error codes or warning lights.

Another sign that your tankless water heater might need attention is when it starts flashing error codes or warning lights. These messages can help you identify what exactly is wrong with your system so that you can fix it before it causes any severe damage.

Insufficient hot water for simultaneous use.

If your tankless water heater is unable to provide hot water for multiple fixtures or appliances running simultaneously, it may indicate that the unit is undersized or that there is a problem with its capacity to handle the demand.

Strange noises or odors.

Unusual noises, such as rumbling or popping sounds, or the presence of strange odors (e.g., a rotten egg smell) can indicate problems with the heater’s components or a potential gas leak, which should be addressed immediately by a tankless water heater service professional.

Causes of Tankless Water Heaters Not Getting Enough

If you have a tankless water heater, it’s important to understand what can cause it to stop working. If you don’t, it could mean you won’t be able to take a hot shower or bath again until the water heater is repaired.

Many people think that their tankless water heater isn’t getting enough heat because they don’t know how to work with them. However, there are many other reasons why your tankless water heater might not be getting enough heat. If this happens, you need to take immediate action so the problem doesn’t worsen.

So, here are seven potential causes of tankless water heater not getting enough heat:

Insufficient flow rate.

Tankless water heaters require a certain minimum flow rate to activate and heat the water. If the flow rate is too low, the heater may not kick in or produce hot water at the desired temperature. This can happen if the water pressure is too low, there are flow restrictors in the plumbing system, or multiple fixtures are being used simultaneously, exceeding the heater’s capacity.

Undersized unit.

If a tankless water heater isn’t getting hot enough, it may be because the unit is undersized and can’t provide enough hot water for your household’s needs. If this is the case, you’ll need to upgrade to a larger model and install it in place of your current unit.

Sediment or mineral buildup.

When your tankless water heater is not getting hot enough, it could be because of sediment or mineral buildup. Over time, the minerals in your water can build up on the heating elements, making them less effective at transferring heat to the water flow. This buildup can also lead to corrosion and other issues that could increase the likelihood of needing repairs.

Temperature setting too low.

The temperature setting on your tankless water heater should be high enough to ensure that you get warm enough water when you turn on your hot faucet but not so high that it wastes energy by heating more than necessary. If your setting is too low, you may run out of hot water sooner than you’d like.

Gas supply issues.

If the water heater is not getting hot enough, check the gas supply. Make sure the pilot light is lit and that there is a constant flow of gas to the burner. If this isn’t working as it should be, call a tankless water heater installation professional to diagnose and fix the problem.

Faulty heating elements or sensors.

If your tankless water heater isn’t getting hot enough, it could be that one of your heating elements or sensors has failed. This will require an electrician to come in and diagnose and repair the issue.

Venting issues. 

If your tankless water heater is not getting hot enough, it could be because the venting system is not working properly. The venting system allows for gas to be released safely from the unit. If this does not work, the unit will not get hot enough to heat your water and will not work properly.

What to Check When Your Tankless Water Heater Is Not Hot?

Your tankless water heater is a pretty amazing piece of technology. It heats water on demand and can save you as much as 30% on your utility bills each month by eliminating the need for an electric storage tank. But what happens when it stops working?

If you have one of these devices, you probably know that they’re not always trouble-free. They can get clogged with sediment, or their pumps might fail. And sometimes they just stop heating water altogether. When this happens, getting your tankless heater fixed as soon as possible is important—but how do you fix them?

Well. There are several things you can check to troubleshoot the issue:

Check the Water Supply

Make sure that you have turned on all faucets and opened all valves as far as they will go. If you have recently installed or replaced a toilet or sink, make sure that the water supply line has been connected properly and that it hasn’t been crimped or damaged during installation.

Check the Gas Supply

If your tankless water heater is powered by natural gas, check for an open gas valve by turning on the gas supply at the outside meter. If you don’t smell gas when you turn on the valve, check to ensure there isn’t any debris blocking its path from the meter to your home. If there is no debris in its path, then look for tankless water heater repair near me to inspect your system from top to bottom.

Power Supply (for electric units)

If you have an electric tankless water heater and it’s not working, check to see if your breaker is turned on. If it is, and if you’re still having trouble getting hot water, then your wiring might be faulty or bad. You can also try replacing the fuse in your breaker box.

Error Codes Or Warning Lights

If your tankless water heater isn’t heating up, the systems could have a problem controlling it. These systems include the power control board and the flow control valve. If these components aren’t functioning properly, they’ll send an error code or warning light to let you know what’s going wrong. You should immediately call a tankless water heater services professional before anything else happens!

Temperature Settings

If you have a tankless water heater, the temperature of your water is important. To check your temperature settings, you can use a digital thermometer or a pH test strip. The temperature should be between 100°F and 125°F. Anything higher than 125°F can damage your tankless heater.

Flow Rate

If your tankless water heater is not generating enough hot water, it may be because there’s too much resistance in its flow path—like if you have too many bends in the pipes or if you have an old faucet with small openings that restrict flow. To fix this problem, try increasing the diameter of your pipes by using coupling reducers and/or pipe bushings (which are available at hardware stores). You can also install new faucets with larger openings, but this will require professional tankless hot water heater installation, so make sure you hire a plumber if necessary!

Clean Sediment Or Mineral Buildup

If you have well water, sediment may have built up inside the tankless water heater and lowered the temperature of the water. To fix this issue, you’ll need to clean out the sediment from inside your tankless water heater. You can use an aquarium vacuum cleaner with a hose attachment to get rid of any buildup inside your tankless water heater. 


You’ll need to make sure that there’s enough airflow around your tankless water heater so it can properly heat up and stay hot throughout the day. If there isn’t enough ventilation for your tankless water heater, it may be unable to keep up with demand and operate at full capacity. 

Professional Inspection

Your tankless water heater has safety mechanisms built in, but they can be damaged or malfunction in ways that are difficult to diagnose without tankless water heater repair professional help. A thorough inspection will also ensure that there’s nothing else wrong with your system and that your tankless water heater isn’t simply not working because of an issue outside of its control. A  qualified plumber in La Grange, KY, or a technician experienced in tankless water heaters can thoroughly inspect the unit, diagnose the problem, and perform any necessary repairs or maintenance.

DIY Vs. Professional Tankless Water Heater Repair

Tankless water heaters are becoming more and more popular in the world of plumbing. They are often sold as a way to save money on your utility bill.

So, when your tankless water heater isn’t working properly, you have two options: DIY vs., Professional plumber’s help.

If you’re looking to repair your tankless water heater, you might be wondering if it’s better to do it yourself or hire a professional.

As with most things, there are pros and cons to each approach. If you’re willing to put in the time and effort, DIY is often a much cheaper route than hiring someone else to do the work for you. However, if you’re not comfortable working on delicate electronics or if you don’t have the necessary tools and skill set, then hiring a professional is probably your best bet.

Here’s a comparison table outlining the differences between DIY (Do-It-Yourself) and professional tankless water heater repair so that you can decide what’s best for your situation.

AspectDIY RepairProfessional Repair
Technical ExpertiseRequires a good understanding of plumbing and electrical systems, as well as knowledge specific to tankless water heatersProfessionals have specialized knowledge and experience in repairing tankless water heaters.
SafetyDIY repairs can be potentially hazardous if not done correctly, risking personal injury or damage to the water heaterProfessionals are trained to handle repairs safely, minimizing risks and ensuring compliance with safety standards.
Tools and EquipmentBasic tools may be sufficient for some simple repairs or maintenance tasksProfessionals have specialized tools and equipment to diagnose and fix complex issues
Diagnostic AccuracyDIY repairs may involve trial and error, potentially resulting in misdiagnosis or ineffective repairsProfessionals have the expertise to diagnose and address the problem accordingly and accurately.
Warranty CoverageDIY repairs may void the manufacturer’s warranty, as some warranties require professional installation or repairProfessional repairs typically maintain warranty coverage, ensuring protection for your water heater.
Time and ConvenienceDIY repairs can be time-consuming, especially if you lack experience or knowledgeProfessionals can efficiently identify and resolve issues, saving you time and effort.
CostDIY repairs may seem more cost-effective initially, but mistakes or incomplete repairs can lead to additional expenses in the long runProfessional repairs may involve upfront costs, but they are more likely to provide a lasting solution, saving you money in the long term.
Complex Issues and UpgradesDIY repairs may not be suitable for complex problems or upgrades, requiring professional interventionProfessionals have the expertise to handle complex issues, perform upgrades, or replace components if needed.

Time To Call Tankless Water Heater Experts In La Grange, KY!

Do you have a tankless water heater that’s not working?

If so, you’re not alone. The statistics are staggering: every year, around 200,000 homes in the U.S. experience some kind of plumbing-related disaster. That’s why we’re here to help!

At Backup Plumbing, we’ve been providing expert tankless water heater repair and installation services for many years now. We know that a tankless water heater can often be confusing, but we will walk you through the process and ensure it is installed correctly.

We offer a wide range of Tankless Water Heater Services in La Grange, including:

– Tankless Water Heater Installation
– Tankless Water Heater Repair
– Tankless Water Heater Replacement
– Tankless Water Heater Maintenance
– Emergency service
– Drain cleaning
– And Many More…

Our licensed plumbers are experts in installing and repairing tankless water heaters in La Grange, KY. We’ll come out and give you an estimate on what it will cost to install a new tankless system or repair your existing one.

At Backup Plumbing, we provide heating services for all kinds of water heaters—including tankless water heater vs tank. So, if you’re tired of waiting for your tank to refill with enough hot water to fill up your tub or do dishes, give us a call today at (502) 829-6561!

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