I’ve identified the main reasons behind the Rheem water heater not heating for both gas and electric heaters from my experience. In gas water heaters, the most common culprits here:
- No gas supply.
- The pilot won’t light or stay lit.
- The main burner won’t light or stay lit.
- Defective gas control thermostat.
- Leaky hot water faucet.
When it comes to the Rheem electric heaters, the main causes behind this issue are:
- No power to the heater.
- Tripped ECO or manual reset limit.
- Faulty heating element.
- Defective thermostat.
- Undersized water heater.
- And more.
However, there are many other potential reasons that can also cause this issue. I’ll discuss all the reasons and their solutions in this guide. So, let’s dive in!
Table of Contents
Rheem Water Heater Not Heating [Gas Units – How To Fix]
Let’s look at the most common reasons why your Rheem gas water heater provides little to no hot water in this section.
01. Setting The Thermostat Too Low
For the sake of starting with the issues that are ready to resolve, I have started with this one. You may be confident that you’ve set the temperature at the right level. But who knows – maybe someone else in your family has tampered with the thermostat and dialed it down.
How To Fix:
Check the position of the gas control knob in the thermostat. If it’s set too low, you’ll have to turn it up to solve the issue. Here are the temperature settings at a glance to help you select the right temperature:
- “Low” means the water temperature will be close to 91°F.
- “Hot” means the water temperature will be near 120°F.
- “A” means the water temperature will be approximately 130°F.
- “B” implies 140°F and “C” means 150°F.
- “Very Hot” means the water temperature will be close to 155°F.
Even if the gas control knob is set at a high temperature, you can turn up the gas control knob further. See if that helps you get hotter water. But only do it as a temporary solution and consult a qualified technician to check your heater as soon as you can.
02. No Gas Supply
You’ll also not get any hot water if there’s no gas supply. That’s because gas is the main fuel in gas water heaters. Without it, the heater won’t be able to light the pilot or the main burner.
If you’re using a heater that runs on natural gas, make sure you’ve paid your gas bills. Otherwise, your local gas company may have cut off the gas supply to your house. A quick way to check it is to see if the other gas power heaters in your homework properly.
If nothing works, that means the gas supply to your entire house has been cut off. But if the other things work, then you have to check the main gas shut-off valve of your heater. If it’s not fully parallel to the gas lines, that means the gas supply is not fully open.
But what if you’re using a heater that runs on liquid propane? In that case, you have to check if you’ve run out of gas and the tank cylinder is empty.
How To Fix:
For natural gas users, the first thing you have to do is pay your bills if you haven’t paid them on time. If the main gas shut-off valve wasn’t in the fully open position, you have to make it fully parallel to the gas lines. That way you can ensure that your heater is getting the proper gas supply.
For liquid propane users, you can refill the cylinder if it becomes empty. Or you can replace it with another cylinder. That’s why it’s handy to have at least two tanks at a time if you run your heater on your LP. You can quickly restore the gas supply and get hot water soon.
03. Power Supply Issues
Problems with the power supply can also lead to you not getting any hot water from your heater. If there are any wiring issues or faults within the power outlet or circuit breaker, the heater won’t work properly.
There aren’t too many Rheem gas water heaters that have an On/Off Switch. But if you’re using the Rheem Gas Prestige Maximus heater, you’ll see such a switch. If it’s turned off, the heater won’t work and you won’t get any hot water.
How To Fix:
First, make sure there’s nothing wrong with the circuit breakers or the power outlet in your house. If you suspect there could be any issues with them, you can consult an electrician to check it out.
For users of Rheem Gas Prestige Maximus heaters, turn on the switch so that your heater works properly. If any of the wires are damaged, replace them so that your heater can work properly and provide sufficient hot water.
04. Undersized Heater
Having an undersized water heater is one of the most common reasons behind the no hot water issue. Your water heater has a limited capacity and it can’t give you unlimited hot water. It’s bound to run out of hot water if it’s pushed beyond its limits.
And that’s exactly what may have happened. If multiple people have been using hot water at the same time, then the stored hot water will get depleted. Your heater will need time to heat the next batch of water. That’s why you may not have any hot water from the heater at the given moment.
How To Fix:
As there’s nothing wrong with your heater in this case, you don’t have to do anything. You can just wait for the heater to heat the new cold water and then use it. When the water heater recovers after such an abnormal demand for hot water, you’ll be able to use it again.
But if this is a daily occurrence and you keep running out of hot water, you have to do something about it. Either you can limit the number of hot water faucets. Or you can upgrade to a new and better heater with a higher capacity that’ll fulfill the needs of your family.
05. The Pilot Won’t Light Or Stay Lit
If you want to use your heater, you have to light the pilot and it must stay lit. The pilot comes on at first, and then, it’ll ignite the main burner. There are many things that can go wrong with the pilot light.
First of all, you have to check if the pilot light in your heater stays lit. You can do it by removing the outer door of the main burner and looking through the viewport. You’ll see a small flame if the pilot is burning.
The status light in the gas control valve can also help you understand if the pilot is light. If it doesn’t light at all, it means the pilot isn’t lit. If it’s a solid color, that means the pilot is off and the thermopile is cooling down. One flash every three seconds represents the normal operation of the heater.
If the pilot isn’t lit or won’t stay lit, there are many things that could go wrong with it. Some of the common issues behind it are:
- The pilot orifice is clogged or the pilot tube is pinched.
- A faulty thermopile.
- Dirty filter grate.
- Lack of combustible air.
- Kinked flex tube.
- Not following the pilot lighting instructions properly.
How To Fix:
As you can see, there’s a lot can that cause pilot light issues. And that’s only the popular reasons. There are many more potential problems there. That’s why I’ve compiled a guide on Rheem pilot light issues for you.
It’ll walk you through all the reasons why your pilot light goes out and how you can fix them. You’ll also learn how you can light the pilot correctly. Hopefully, you’ll no longer have any issues with the pilot light in your heater after going through my detailed guide.
06. The Main Burner Won’t Light Or Stay Lit
You already know that lighting the pilot is important for the heater to produce hot water. The same goes for the main burner. In fact, the heater starts heating the hot water only when the main burner has been ignited.
So, it’s obvious that you won’t get any hot water if the main burner isn’t lit. Just like the pilot light, there are many things that can go wrong with the main burner. All these things can keep it from burning or styling lit. The most common main burner issues are:
- There’s air in the gas lines.
- The gas valve isn’t fully in the open position.
- Blockage in the inlet or exhaust pipes.
- The pressure switch isn’t working properly.
- The combustion chamber is dirty.
- Malfunctioning main burner assembly.
How To Fix:
If there’s air in the gas lines, it’ll have to be purged. The gas shut-off valve needs to be moved to a fully open position if it already wasn’t there.
You also have to remove all the dirt and debris from the intake and exhaust pipes. If you get the dirt out of them, the pressure switch should start working properly. If it still doesn’t work, you’ll have to replace it.
Finally, you’ll have to check if the combustion chamber is dirty. If you see a yellow flame through the viewport, that’s a good indication that you have a dirty combustion chamber. The yellow flame comes from the main burner burning the dirt.
You have to take out the main burner and clean the combustion chamber. Make sure you’re not blocking the air inlet openings. It’s important for them to be open to let in air and burn the pilot and the main burner.
While you’re removing the dirt from the combustion chamber, clean the main burner as well. If the main burner still doesn’t light or stay lit after fixing these issues, the burner itself is most likely faulty. You’d have to replace it in that case.
07. Defective Gas Control Thermostat
The gas control valve is one of the most important components in Rheem gas water heaters. It plays a crucial role in supplying gas to both the pilot and the burner. Besides, it also regulates the water temperature as the thermostat is built into it.
So, there can be a wide range of issues in your heater if the gas control thermostat doesn’t work properly. For instance, it can give too much too hot water if it doesn’t sense that the water has already reached the desired temperature set by you.
The reverse of that is also true. It can give you cold water at the hot water faucet if it thinks the water has already reached the desired temperature when it hasn’t. A faulty gas control valve can also lead to gas and water leaks.
How To Fix:
As the gas control valve is a relatively expensive component, you can’t just replace it on a whim. You should make sure that you actually have a faulty gas control valve by testing it. If it turns out to be bad, only then you should move on to replace it.
You may think that doing so by yourself is complicated. But that’s not the case. Follow my Rheem gas control valve replacement guide to learn all about testing and replacing it on your own. Hopefully, you’ll get hot water from your heater again after changing the gas control valve.
08. Low Gas Pressure
If the gas supply is completely cut off, even the pilot light won’t burn. So, you’ll have no hot water at all from your heater. But there could be instances when you get hot water from the heater but it’s not hot enough. That means it’s lower than your desired temperature.
One possible culprit, in that case, is having low gas pressure. If there is low gas pressure, the main burner won’t be able to heat the water at full potential. That’s why you’d get hot water that’s not at the right level.
How To Fix:
You have to check the gas pressure and manifold pressure. Then, you’d have to correct it if needed. The correct gas pressure for most Rheem heaters is 14.0 in. w.c. maximum or 3.5 kPa. That’s usually the case for both natural gas and liquid propane.
You can also find the minimum inlet gas pressure in the rating plate of your heater. So, you’ll have the values for both the minimum and gas pressure. Now, you can check the pressure and see if it’s in the normal range. If it’s higher or lower than that, you can contact your local gas supplier to fix it.
09. Chamber Sensor Failure
There’s a component in your Rheem gas water heater that checks whether the main burner is burning properly. That component is the chamber sensor. It senses the flame from the main burner and signals the gas control thermostat to keep supplying gas.
When it doesn’t sense the flame, it won’t send that signal. So, the gas supply will be shut off and the main burner will no longer burn. So, the heating of the water would stop and you’ll no longer have any hot water.
A chamber sensor is a good tool to avoid gas-related accidents as it prevents the supply of gas when the burner is off. But when the sensor goes bad, it can give faulty readings and turn the gas supply off even when it needs to be on. That may be what happened with your heater and why you have no hot water.
How To Fix:
First, you have to check whether you have a bad chamber sensor or not. Chamber sensor failure doesn’t necessarily mean that it’s bad. It could also be dirty. You’ll need a multimeter to test the chamber sensor.
Check out my Rheem chamber sensor guide to learn more about it. I have walked you through how you can test and replace the chamber sensor. You can do it all yourself or hire a professional technician to do it.
10. Tripped Combustion Shut-Off Device
There’s a safety device in your Rheem gas water heater called the combustion shut-off device. It’s designed to shut off the operation of the water heater when undesirable combustion occurs.
For instance, the air inlet openings being blocked or flammable vapors being present can trip this device. So, your heater won’t work at all and you’ll get no hot water from it.
How To Fix:
The tripping of the combustion shut-off device is no joke. It’s a serious matter. So, you should immediately consult a qualified technician if it happened. He’ll guide you on what to do to fix it and get hot water from your heater again.
11. Faulty Mixing Valve
Using thermostatic mixing valves is a great practice as it can reduce the temperature of the hot water faucet. So, it acts as an extra layer of safety to protect from scalding.
However, thermostatic mixing valves can go bad and cause problems for you. They can be stuck in a closed position and give no hot water at all. Check all the other hot water faucets in your house.
If all of them are working fine and you can isolate the issue to one particular faucet, you could have a bad mixing valve. The temperature can also fluctuate or the water can even be too hot due to a malfunctioning mixing valve.
How To Fix:
Cleaning the maximum valves can solve the issue at times. If you live in an area with a hard water supply, the valve may have been clogged due to the sediments in the water.
So, you may able to salvage it with a thorough cleaning. However, they can also go bad, and cleaning won’t help there. Thermostatic mixing valves aren’t repairable. So, you’ll have to replace them in those cases.
12. Sediment Build Up
If you’re facing a fairly old water heater and you’re not getting sufficient hot water, mineral deposits can be the main culprit here. As time passes, sediments settle in your tank and settle at the bottom.
So, the heater loses its efficiency and can’t transfer the hot water soon enough. If you’re facing this issue, it’s still not that serious and can be easily fixed. But if matters get worse and your tank gets corroded, it can start leaking.
You can check out the base of your water heater’s tank and see if it’s leaking. A leaky tank will also be inefficient and it’ll give you less hot water. It’s also unsafe to use the water heater in that condition.
How To Fix:
If there are mineral deposits at the bottom of the tank, you’ll have to flush the tank. Hopefully, that’ll get rid of most of the sediments and you’ll get hot water again. As a preventive measure, you should always change the anode rod on time so that your tank stays safe.
But if you haven’t changed your anode rod when required, your water heater’s tank will start leaking. No quick fix is available in case of a leaking tank. Your only option will be to replace the entire tank.
But that’s only if the source of the leak is the tank itself. There can be other sources from which the tank is leaking. Check out my Rheem heater water leakage guide to learn about all the possible areas of a leak. You’ll also learn how you can fix them in detail.
13. Leaky Or Open Faucet
If you have a hot water faucet that’s leaking, it’ll keep depleting the hot water in the tank. So, the main burner in your heater will have to become active again to heat the water.
The same thing happens if you leave a hot water faucet open for a long time. The hot water will be consumed and new cold water will have to be heated. That’s why you may not get sufficient hot water when you need it.
How To Fix:
If you left a hot water faucet open, the fix is simple. All you have to do is close it and that’ll solve the issue. However, if you have a leaky faucet, you’ll have to replace it with a new one.
You have to make sure that all the hot water faucets are closed when they’re not being used. Otherwise, you’ll keep running out of hot water now and again. Even a small leak on the hot water side can cause issues. So, close the faucets all the way and replace the leaky ones to fix this problem.
14. Plumbing Crossover
If you’re getting cold water from the hot water faucet at full pressure, it could be due to a plumbing crossover. It’s a clear case of cold water being supplied to the hot water faucet.
If there was a blockage or mineral deposits in the pipe, you’d have either gotten no or little hot water. But as you’re getting cold water, there’s a strong chance that there’s a cross-connection somewhere.
That faulty connection is allowing the cold water to come through the hot water faucets. However, it can also be the result of a bad thermostatic mixing valve. So, make sure that you rule out the mixing valve first.
How To Fix:
If there’s a mistake in the plumbing, then you’ll have to get a plumber to fix it for you. Getting cold water at a specific faucet is also a strong sign of having a plumbing crossover. As soon as the plumber fixes the issue, you should get sufficient hot water without any issues.
15. Cold Water Supply
Sometimes, there may be nothing wrong with your water heater and you’d still get colder water. You have the cold weather to blame in those instances. The truth is that it’ll just take the heater longer to heat the water if the cold water supply gets even colder.
Moreover, the pipes may be ice cold at the same time. So, the hot water will lose some of its heat when it goes through the pipes. The longer the distance between the hot water faucet and the tank, the colder the water will be.
How To Fix:
There’s no quick solution to this problem. It’s normal that the heat cycle will be longer when the water supply is colder. But you can take an extreme preventive measure if you want.
You can insulate the pipes so that the external weather has minimal impact on the pipes. But even then, you have to be prepared that colder water will take longer to heat up compared to usual water.
Rheem Water Heater Not Heating [Electric Units – 10 Easy Fixes]
I’ll discuss the main reasons why your Rheem hot water heater is not heating the water properly in this section.
i) No Power To Heater
The first thing you should always check when your electric heater isn’t working is the power supply. Check if the heater has power. If it doesn’t, it could be a simple issue.
More often than not, the circuit breaker will be tripped or the fuse to the heater will be blown. Besides that, there may have been a power outage for which the electric heater got turned off.
Remember that a circuit breaker that’s in the correct position will also stop the power supply if it goes bad. If you’ve had a recent storm, there’s a strong possibility that your circuit breaker has gone bad.
Check the other electrical devices in your house. If none of the other electric components in your home are working, it’s most likely a power outage.
How To Fix:
The heater will be connected to a breaker in most homes. If that’s the case with you as well, check the circuit breaker. If it’s tripped, you need to reset it and that’ll solve the issue.
Sometimes, you’d face an unwanted problem with your circuit breaker. It’ll keep on tripping even after you reset it. There are high chances that it’s due to a bad circuit breaker and you’d have to replace it.
But there are other potential reasons behind the continuous tripping of the circuit breaker as well. Check out my Rheem circuit breaker keeps tripping solution guide to learn more about those reasons and their fixes.
The other scenario is that the breaker is fine but there’s no power supply to your house. In that case, it should come back after a while. You can contact your local utility company to know the updates and get a timeline on when you can expect the power to come back.
ii) Tripped ECO
There’s a safety device in Rheem electric water heaters called the ECO. The ECO or the Electric Cut Off device is located above the heating element. It has direct contact with the tank surface.
The job of the ECO is simple – to protect the users from scalding. So, the ECO automatically shuts off the power to the water heater when the water temperature gets too high.
How To Fix:
If the ECO in your water heater gets tripped, you can easily solve that issue. All you’ll have to do is press the reset button and that’ll do the trick. The reset button is located right above the upper thermostat. Once you press it, the heater will be up and running in no time.
How To Reset Rheem Electric Water Heater?
Follow these simple steps to reset the water heater if the ECO got tripped:
- Turn off the power to the electrical heater by switching off the circuit breaker that supplies power to the heater. There should be a label on the left side that should point you to the right breaker in case you’re having trouble finding it.
- Then, you’ll have to remove the screws holding the upper panel access cover in place. You can use a Philips screwdriver to undo the screws. Then, set the screws aside and be careful not to lose them.
- Take off the access panel cover. Unfold or remove the insulation that you see after removing the cover. Then, you should have eyes on the red reset button. Press it to reset your heater.
- You should hear a clicking sound if the unit is reset. If there was no clicking sound, it means the heater wasn’t reset. It also indicates that the ECO wasn’t tripped in the first place and there’s another issue with your water heater. You need to keep on diagnosing the root problem in that case.
- But if the unit was reset, you’ve fixed the issue. You can put the insulation and the access cover back into their original positions. Then, turn the breaker back to the “On” position and restore the power supply to the heater.
Remember that it’s not a big deal if the ECO gets tripped once in a while. But if it gets tripped every now and then, something else is also wrong with your heater. It’s due to a faulty thermostat in most cases. But I’ll take a detailed look at thermostats in another section as I move on.
iii) Heating Element Failure
Another common issue behind getting no hot water or inadequate hot water is a failed heating element. There are usually two heating elements in most Rheem electric heaters.
They’re arguably the most important components of the water heater as it’s their job to heat the water. When any of them goes bad, the water will not be able to reach the desired point.
Generally, it’s the upper heating element that fails if you get no hot water at all. On the other hand, you’d usually have a small quantity of hot water if the lower heating element has failed.
But those are just general speculations and won’t happen all the time. So, you should test both heating elements to be certain if any of them is really bad.
How To Test Rheem Electric Heater Heating Element?
Testing the heating element is an easy process if you have a multimeter. All you need to do is collect the readings and that’ll determine if the heating element is good or not. Follow these steps to test the heating element in your electric water heater:
- Shut off the power to your water heater by turning off the circuit breaker that goes to the heater.
- Remove both the upper and lower access cover panels and the insulations in front of the heating elements.
- You’ll see some plastic covers at this stage. They’re snapped into their position. So, move them back and forth and remove them. The heating element is located right under the thermostat. You’ll only see the outside screws of the heating element.
- Before testing the heating element, you should check that your multimeter is working properly. Touch the two probes of the multimeter with one another. If you get a reading between 2-5 Ohms, it’s working correctly.
- Now, it’s time to double-check if the power supply is truly off. Set the multimeter to 750 ACV and touch the thermostat screws with the multimeter probes. If you get a small reading, then you can be certain that the power supply is actually turned off.
- Now, you’re ready to test the heating element. Set your multimeter to the lowest Ohm settings. Touch the probes of the multimeter to the heating element screws. You can connect the probes to any of the screws. It doesn’t matter which way you go. Note down the readings.
If the reading was between 10 to 16 Ohms, that means the heating element in your heater is okay. If the reading is outside that range, that means you have a bad heating element.
Make sure you check both the heating elements following the procedure you learned above. You’ll have to follow the same steps for the other heating element. If the reading is outside the range on that one as well, that means the other heating element has also gone bad.
How To Fix:
If you have a bad heating element, it’s not possible to repair it. A bad heating element is usually severely corroded as well. Here’s a picture of what a completely corroded heating element looks like:
You’ll have to replace the faulty heating element to get your heater to work again. Don’t worry, I’ve broken down the process of replacing the heating element into easy steps.
How To Replace Rheem Heater Heating Element?
Make sure you get the right replacement part when you’re replacing the heating element. There should be a sticker on your water heater showing the correct configuration. Here’s an example of what you need to look for:
With that said, you’ll also need an element wrench to remove the old heating element and install the new heating element. With that said, here are the steps you need to follow to replace the heating element:
- Turn off the power to the heater and wait for it to cool down. Then, remove the upper panel access cover. Unfold the insulation and remove the plastic cover to access the thermostat.
- Drain the water heater to a level that’s below the heating element you want to replace. If you’re replacing the upper heating element, you don’t have to drain the tank all the way. If you’re going to replace the lower heating element, you should drain the entire tank.
- Draining the heater is an easy process. All you have to do is attach one end of the garden hose to the drain valve and the other to a floor drain. Then, open the drain valve and let the water go out.
- Next, you’d have to remove the heating element. Disconnect the wires from the screws of the heating element first. You’ll have to loosen the screws to do it.
- Now, it’s time to remove the old heating element. Use an element wrench to loosen the heating element and pull it out.
- Then, put the new heating element in place of the old one. Tighten it with the element wrench, and put everything back in place. Turn on the cold water supply and check for leaks.
- If there are no leaks, you did a great job replacing the heating element. If there are leaks, shut off the cold water supply immediately and tighten the heating element. Keep tightening the heating element until water stops leaking out of it.
That’s how easy it is to replace the heating element on your own. Wait for the tank to get filled with water before you turn on the power to the heater. You have to do that because the heating element can get shorted again if the tank isn’t filled with water.
Once the tank is full, turn on the heater. Wait for at least a couple of hours for the water to get your desired temperature. Once that period has passed, you can start enjoying the hot water from your heater once again.
Keep in mind that the specific procedure could vary depending on the model you own. That’s because the type of heating element you have could be different from the one I showed.
For example, if you have a screw-in type heating element, you’ll need an ½ inch element wrench. For phalange heating elements, it normally requires a ⅜ heating element. As the first type is more common in Rheem electric heaters, that’s the one I covered.
iv) Thermostat Issues
The two most dangerous culprits when it comes to an electric water heater are the heating element and the thermostat. If it’s not the heating element that’s causing the issue, you should check the thermostat next.
The most common reason why you have inadequate hot water is often because you’ve set the thermostat too low. But that’s an easy problem that you can fix without too much trouble.
