Why Hot Water Heater Not Heating – Plumber Expert Explains

A hot water heater is an essential plumbing fixture, especially during the winter. However, just like many home appliances, it may fail at times. One issue is when it no longer produces hot water. It’s good to know why it no longer heats cold water so people can take the proper action to ensure a continuously heated water supply.

So, I searched, why hot water heater not heating? Your hot water heater is not heating because of a damaged dip tube, which pushes cold water to the bottom for heating. If there’s a hole or crack in this tube, it may accidentally release cold water elsewhere in the tank.

Experts from WM Henderson, a plumbing company in Philadelphia, Pennsylvania, suggest calling a certified technician to replace the dip tube because the installation is a complex process. 

Moreover, excessive sediment buildup may affect hot water release because calcium and magnesium remain at the tank’s base, occupying the space reserved for hot water. Flushing the water heater unit is often a solution to remove these minerals.

Why Is My Water Heater Not Heating After Replacing Elements and Thermostat?

Your water heater is not heating after replacing your elements and your thermostat because it has a tripped circuit breaker. Other reasons for the lack of hot water after replacing parts is that there is scale buildup, improper wiring, bad replacement parts, or feed supply problem.

Have you waited for an hour for your water heater to function appropriately after replacing elements and thermostat? It may only take longer to heat the water. However, if the issue persists, here are some of the reasons:

  1. Circuit Breaker Tripped

How will you know if the circuit breaker is the problem? Check your breaker box. If the double pole breaker for the water down is down, it can cause your water heater issue. Try pulling up the breaker to see if it will solve your problem. If the tripping recurs, you should call an electrician to investigate.

  • Scale Buildup

Accumulated scales can be the culprit! Flush the water heater annually and descale it too. 

  • Improper Wiring

The wiring connections can also cause problems, especially if you installed the elements and thermostat. Check for broken wires or a loose link. However, don’t forget to shut off the main power supply before checking the connections and wires.

  • Defective Elements and Thermostat Parts

Before testing the parts, you should shut off the main power supply then use the multi-meter to get the lowest ohms reading. Next, you should take the reading of the element. If it’s between 10-23 ohms, you have no issue. However, it’s defective if the number is extremely low or infinite. Do the same with the second element, then the thermostat. Replace the faulty parts.

  • Monitor the Feed Supply

You should call an electrician for this test because it requires handling 240volts. 

If you were considering replacing your residential hot water heater, the following table will help. I researched responses left in various plumbing forums to find out the brands that plumbers find satisfying. This table will help you to quickly narrow down your search.

Recommended Residential Hot Water Heater BrandsPercentage of responses
Rheem (click to get your tankless model delivered)35%

Pilot Light Is on but Still No Hot Water

The pilot light is on, but this still no hot water because of a faulty heat sensor. Also, there could be sediment buildup, a broken thermocouple, or a gas valve that isn’t on. However, you can solve these problems quickly.

Issues can arise, and when something comes up, what you can do is troubleshoot to try fixing it. Here’s a list of what you can do:

  • Check your water heater.

You can do a visual inspection then open the cover plate to check if the burner is firing. Next, turn the temperature dial to low or vacation mode before returning to the desired temperature. If this does not work, you can switch to minimum or vacation mode again. Then, move the dial to about 10 – 20 degrees more than your desired temperature. 

This trick works if the thermostat is old, and drifting occurs. Consider moving the dial to your desired temperature to avoid scalding if it works. Faucet temperatures should be up to 140 degrees Fahrenheit only, but if you have seniors or children, you should set it to 120.

  • Test for Sediment Accumulation

Thermostat malfunction can occur if there’s sediment buildup causing it to achieve the desired temperature before the water does. If you hear banging or popping noises or bad-smelling or dirty-looking water, you should call a professional.

  • Inspect the Thermocouple

The thermocouple measures temperature, and you should call your plumber if it needs replacement. However, you may check if there’s rust around it. You may vacuum or brush the pilot and burner element area. On the other hand, leave the job to a professional to be safe.

If you can’t see rust, check the pilot flame and sensor. The gas control valve won’t open if the thermocouple can’t sense heat. Moreover, you may replace the thermocouple if troubleshooting doesn’t work. But, again, you should call a plumber to do the job for you.

My Rheem Gas Hot Water Heater Is Not Heating Water

Your Rheem gas hot water heater is not heating water because of an unlit pilot light. Another problem can be a faulty thermostat, loose-fitting, or faulty relief valve.

Your Rheem water heater may be experiencing a problem, but before you call a plumber, check these tips:

  1. Check if the gas heater has power. 

Give your water heater about 15 minutes to produce hot water. If water from the tap is still cold, you already know that your unit isn’t doing its job. If the pilot light isn’t on, you should check the user’s manual to relight it with a BBQ lighter. On the other hand, if your unit’s electronic ignition won’t fire, you should replace it. You should contact a professional to do the job.

  • Adjust the thermostat.

Refer to your user’s manual on adjusting the thermostat’s setting. You may need to set it to a higher degree. However, remember not to put it higher than 120 Fahrenheit to prevent scalding burns. If you must replace the thermostat, I recommend the Rheem UV11698 Thermostat that is available on Amazon. Click here to have it delivered right to your front door.

  • Check for leaks.

Your water heater may leak because of a loose component. Therefore, you should check the water pipe connections and tighten them. Moreover, you should check if the relief valve is releasing water. 

  • Replace the relief valve.

If the water continues to drip from the relief valve, you should replace it. However, if the leak isn’t coming from a relief valve or fixture, your tank can be the source of the leak. It helps if you consider buying a new water heater. To

How to fix hot water tank thermostat problems

Hot water is essential, especially during the winter. Therefore, it’s critical to immediately fix any hot water tank thermostat problems. Here are some easy-to-follow steps:

  • Find the thermostats.
  • Check if the thermostats have power.
  • Turn on the thermostat to check if it’s functioning.
  • Change the thermostat if the upper part doesn’t work correctly.
  • Replace the upper system if it has power but does not produce hot water.

Follow these steps if you should adjust the thermostat:

  1. Find the temperature control knob, which is usually near the heat source. It should be easy to locate because it’s on the front and lower part of the heater.
  1. Note the arrow or small black line above the knob to learn the thermostat’s current temperature.
  2. Set the temperature from 105 to 120 degrees Fahrenheit.

Most water heater tank issues are manageable and repairable. However, a leaking tank requires replacement. Other water heater problems include a sacrificial anode rod, the drain valve, a dip tube, the cold water inlet, or a pressure relief valve. It’s best to contact a professional to check your water heater because they’re the expert in determining if it requires repair or replacement.

Why Is My Instant Gas Hot Water Not Working?

Your instant gas hot water is not working because of mineral buildup. Also, there could be an automatic shutoff of heat exchange, ignition failure, or blocked exhaust. You should check your system to determine the actual cause.

  • Mineral Buildup

Hard water containing magnesium and calcium can damage your instant gas hot water system. In addition, the mineral buildup can block valves and leave the parts damaged or prevent hot water from getting to you. Therefore, you should regularly clean your unit using white vinegar. Moreover, it would be best to get a professional cleaner annually to ensure that your system is in tip-top shape.

  • Cold Water Sandwich

A cold water sandwich is an intermitted burst of hot – cold – hot water. It’s a prevalent problem that an instantaneous unit has. For example, hot water remains in your pipes after your family member finishes a shower. 

You get the leftover hot water if you follow and turn on the shower. However, water in the pipes turns cold, and you get an icy blast. Fortunately, it’s only for a short while because heated water comes up again. To avoid getting a cold-water sandwich, you should turn on the shower to drain the pipes before jumping in as soon as the hot water returns.

  • Automatic Shutoff of Heat Exchange

If you have an old instant gas hot water unit, you may get an icy blast during your shower because the heat exchange shuts off to prevent overheating. If you always experience freezing water in the shower, you should contact a plumber to check if you can upgrade your hot water system or buy a new one.

  • Ignition Failure

Your unit has an ignition mechanism used to light the internal burner. However, if you get icy water from the shower, it may mean that the burner fails to heat the water. You can check the gas valve and its connections. On the other hand, the ignition pack may be the issue if you can’t find a problem with the gas supply. You should hire a professional to solve ignition failure.

  • Blocked Exhaust

Your instant gas hot water system may have an internal problem. Usually, you’ll see the manifestation on its exterior. First, a blocked exhaust struggles to bring air inside the unit for combustion. Next, you must take out the obstructive material or debris. If you can’t solve this issue, you can call a professional.

What Are the Signs That Your Hot Water Is Going Out?

The signs that your hot water is going out are:

  1. The inability to supply enough hot water.
  2. Leaks in your hot water tank.
  3. Odd noises from the hot water unit.
  4. Rust in water that is within your hot water tank.
  5. An old hot water system.

A dysfunctional hot water unit can only result in more problems. So if you know these signs that your heater is going out, it’s time for a new one.

  • Insufficient supply of hot water

If your heater can no longer supply enough hot water for the family and your activities, you should realize that it’s failing. For example, you may notice that you’re waiting longer for your hot water, or you often get an icy blast while in the shower. Moreover, you no longer have sufficient supply to wash your dishes while a family member showers.

  • Leaks

Your old water heater is now leak-prone. Therefore, you don’t get enough hot water. Moreover, you notice your water bill is skyrocketing unnecessarily. You should contact a plumber to check your water heater for leaks immediately.

  • Odd noises

A new water heater is often efficient and doesn’t make much noise. On the other hand, if your old one makes odd noises, you should shut it off and call a professional for repair.

  • Rust in water

Old water heater systems start to rust inside, and you’ll notice it in your hot water. You should contact a plumber immediately because it’s dangerous for you to consume water with rust. Moreover, be prepared to invest in a new one because it’s more cost-efficient to buy.

  • Old age

If your hot water system is at least ten years old, you should consider replacing it. However, if you’re not willing to buy a new one, you should hire an expert to flush it yearly.

Final Thoughts

A water heater is one of the valuable appliances at home. It’s a big help to accomplish daily tasks; therefore, it’s critical to keep it working to ensure uninterrupted supply. In some cases, you can troubleshoot issues with your heater, but you should let an expert fix complex problems involving your water heater.

Aron Blake

I am the lead copywriter on Homezesty and the Webmaster. I have a lot of experience in home renovations and the creation of style. I enjoy writing and sharing my tips on how to create the best living environment. My Linkedin Profile, My Twitter Account

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