Modern electric tank water heaters almost always come with two separate heating elements. However, without notice, you may find your water heater only has one working element. It’s also not unheard of for one of the elements on a dual element system to stop working, so you need to know whether you can run a water heater with only one working element.
So, can you run a water heater with only one element? Yes, a water heater can still run if the bottom element quits. However, the water heater won’t run efficiently and likely won’t produce enough hot water to satisfy your family’s needs running on just the top element.
In most water heaters, the top heating element controls the thermostat and will still work even if the bottom element fails. So provided the top heating element is working, it can still produce some hot water even if the bottom heating element fails. However, if the top element fails, the water heater will not produce any hot water because the thermostat will not trigger the bottom element to run, even if it’s in good condition.
Water heaters that are 20 gallons or less typically only have one heating element. Water heaters 30 gallons or more are dual heating element systems. If only one heating element is working in a dual heating element system, the water heater will not produce as much hot water. It will run less efficiently than if both heating elements are working correctly.
The rest of this article will discuss how water heater elements actually work, compare single element and dual element systems, and talk about replacing a broken heating element on both a single and dual element system.
How Does an Electric Heating Element Work?
A heating element is what heats the water in your electric water heater. Metal coils extend into the heater, and the electricity that runs through these coils heats the surrounding water.
Water enters your heater through a tube at the bottom of the tank. This water, while initially cold, will be heated by the element. All electric water heaters have at least one element positioned at the bottom of the tank to ensure all of the water is heated.
The default temperature of a heating element is typically set to 120 degrees Fahrenheit. You can still change this manually via the thermostat attached to the element if you prefer a different temperature.
Single Element Water Heaters vs. Dual Element Water Heaters
Dual element water heaters are a relatively recent introduction to the water heater market. For a long time, the only option for consumers looking for an alternative to gas water heaters was an electric water heater with a single heating element. But once dual element electric water heaters hit the market, it was immediately clear that they were superior to the single element models.
Nowadays, almost every modern home has a dual element water heater system. There are two reasons for their popularity: efficiency and cost.
Dual Element Water Heaters are More Energy Efficient
One major reason for the popularity of dual element water heater systems stems from the fact that they heat water faster and more efficiently.
Single element water heaters only have one source of heat located near the bottom of the tank, so it can take a while for the water at the top of the tank to heat up. This can be a problem if you have no hot water, as you’ll have to wait longer for the water near the hot water outlet to warm up.
Dual element water heaters solve this inefficiency. The two heating elements coordinate with each other to ensure there is always hot water at the tank’s top. If the water temperature at the top of the tank is lower than the top thermostat’s temperature, then the top heating element will turn on and begin the warming process.
Once the water at the top of the tank reaches the temperature indicated by the thermostat, the top element will turn off, and the bottom element will turn on. The bottom element will then heat the rest of the water in the tank to the desired temperature.
In a nutshell, the top element ensures that hot water is replenished quickly, so you don’t have to wait a few hours to take a shower whenever someone else uses all of the hot water.
The bottom element ensures the bulk of the water sitting in the middle and bottom of the tank is heated once the water at the top is taken care of, which means you’ll have a larger supply of hot water once the bottom element does its job.
Dual Element Water Heaters Can Save Money
The other benefit of a dual element heater is that it generally costs less to use than a single element heater. The dual-element system uses less energy overall than a single element system, so you’ll find some savings when the electric bill comes each month.
I should note that dual-element maintenance can be more costly than single element maintenance. This is simply because there are more parts to replace. It can also be a bit more complicated to replace an element on a dual system, as the top and bottom elements are two separate devices.
If the top element fails, you need to replace it with another top element. You wouldn’t be able to use an extra bottom element to replace a broken top element, as the two aren’t interchangeable. Most people will also change out the thermostat when the top heating element is replaced.
Will a Water Heater Work if One Element Fails?
Modern water heaters are designed with the thermostat connected with the top heating element. If the top heating element fails, the thermostat will not allow the bottom element to turn on even if it is in good condition.
However, if the bottom element fails, the top element will continue to work. However, the hot water supply will be limited, resulting in hot water for a limited amount of time, followed by lukewarm water then cold water.
Replacing a Broken Water Heater Element
If one of your heating elements fails, you’ll need to know how to replace it, so you don’t have to start getting used to cold showers in the morning.
Replacing a water heater element is a relatively easy job for a do it yourself homeowner. If you can follow a few simple steps, you can replace your water heater element. However, if not, you can always call a licensed plumber.
This article won’t dive into the nitty-gritty of replacing a bad water heater element. If you need a step-by-step guide on how to replace a heating element, you can read our article Test & Replace a Bad Water Heating Element: DIY Guide.
A bad thermostat can also contribute to a heating element failure. In our article Test & Replace a Water Heater Thermostat: DIY Guide, we outline how you can replace the thermostat when replacing the heating elements.
That being said, I will list a few important things you need to consider when choosing a replacement element
Getting the Right Water Heater Element
All heating elements are not created equal. You need to make sure you know the exact kind of element currently installed in your heater so you can get a suitable replacement. Here are a few different things you’ll need to look out for:
- Check whether your element is fastened with screws or bolts. Most modern elements are screw-in, but it’s worth checking if your setup differs from the norm.
- Top elements and bottom elements are entirely different devices. You can’t replace a top element with one designed for use on the bottom, and vice versa.
- Ensure the wattage of the replacement element is lower than or equal to the wattage of your current element. Do not buy a replacement element with a higher wattage than the one you are currently using.
- Determine whether your element is a high watt density element, a low watt density element, or a lime life element.
High Watt Density Element
High watt density elements are the most common kind of water heater element found. A high watt density element will likely be the same kind of heating element inside your existing water heater.
High watt density elements have a short life span because they corrode quicker than other water heater elements. These elements are generally the most inexpensive too.
Low Watt Density Element
If you have hard water, a low watt density element may be best for your water heater. The design of low watt density elements has more heating space. This helps maintain efficiency despite their lower watt density.
A low watt density element can replace a high watt density element provided the wattage and voltage match. These elements generally cost more than high watt density elements.
Lime Life Element
Lime life elements have a very low watt density with a high-quality nickel and stainless steel surface. This helps resist the build-up of limescale. Lime life elements are considered the most expensive to buy, but they have a limited 5-year warranty. Lime life elements usually last longer than the water heater will.
Proper maintenance will go a long way towards helping you get the most out of your water heater. If you’d like to double the lifespan of your water heater, check out our article Water Heater Maintenance Tips to 2X Your Tanks Lifespan.