Are water heater elements universal? What if you need to change corrosive water heater element?
To properly install water heater elements and make sure your heater runs successfully, it’s of utmost importance to choose the right one. So, how do you do it? Are there any differences between water heater elements that you should know about?
Keep on reading to find out about the useful information and tricks this topic holds.
Are water heater elements universal and how they work?
First, each water heater element contains a thermostat that serves to measure the temperature of the water.
Secondly, each water heater usually contains two separate water heater elements. These two water heater elements work separately in order to heat the water properly.
Usually, the water heating element on the top is the one that turns on first. When it heats the water to a certain temperature, the top heater turns off, and the bottom one turns on.
This means that the top and the bottom water heating elements are never turned on at the same time. They work one at a time – interchangeably.
This cycle repeats only when the heater is full of water – so that the upper element detects cool water.
When you shower and use the hot water, the tank will heat up from the bottom. This means that the lower heating element will detect cool water first and start the water heating process.
Soon as the upper heating element detects cool water, another heating cycle begins.
A thermostat is also a really important part of each water heating element as it’s what connects to an element.
If a thermostat gets damaged in any way, it inevitably results in no hot water in the water heater.
Are Upper and Lower Water Heater Elements The Same?
The lower and the bottom water heating elements are identical. If found in the same fixture, they are usually made from the same materials and have the same properties.
However, when replacing them, make sure to properly research them when buying new ones. This is because water heating elements can vary in material, density, wattage, and endurance.
QUICK TIP: If you set the heating elements to the same temperature, the bottom one will always turn on first. In order to always have hot water, it’s useful to set the top heater slightly higher.
Types of Water Heating Elements
Different types of water heating elements can be classified both based on their attachment and the material they are made of.
Let’s start with the attachment differences in elements of different water heaters.
Different types of attachment styles of water heating elements include:
If you dig in on the topic of different attachment styles, you may also notice this differentiation:
- Flange-type water heating elements
- Threaded water heating elements
Attachment styles are self-explanatory. You screw in the first type and bolt in the type of heating element with the bolts, and so on. 
Flange-type water heating elements usually have smaller bolts than threaded ones. On the other hand, threaded types usually require the use of a large wrench to be installed on the side of the tank.
Now, let’s take a look at the differences in materials from which the water heating elements are made of.
The most common materials of water heater elements are:
- Thick film heating elements
- Ceramic heating elements
- Metal heating elements
Thick film heating elements include heating elements that are most common are ones from stainless steel and aluminum. They are low-energy consumers and have a quick thermal response.
Silicon Carbide and Molybdenum Disilicide are among the most commonly used ceramic heating elements.
Silicon Carbide heaters can endure up to 1,600 to 1,700°C temperatures when heating. As they don’t deform at any temperature, they are typically more solid than metallic ones. 
Molybdenum Disilicide ceramic heaters are combined with metal and can achieve temperatures up to 1,900°C.
The most commonly known and used metal heating element is nickel. Nickel heating elements can achieve temperatures up to 1,100 to 1,200°C.
If you measure in Fahrenheits, you should note that the typical temperature of water heaters is set to 120 Fahrenheits.
That being said, nickel and stainless steel are usually praised as the best materials for water heating elements. This is because of their watt-density properties, which is our next point.
Are water heater elements universal in watt density?
When we speak of the density of the element, we refer to the surface area of the water heating element.
Generally speaking, the lower the density of heating elements – the more surface area.
Also, the density of elements is interconnected with the wattage. This is sometimes called “watt-density” – stick with us as we explain this later in this article.
Density of Water Heater Elements
If we were to make a classification based on the density of heaters alone, it would look like this:
- High-Density Elements
High-density elements are usually made of copper (sometimes coated with zinc or other material). This option is the least expensive one, but also provides the lowest quality of all 3 options.
However, it is very likely that this is the type of heating element you’ll see installed originally in your water heater. It can come either with a flange or a threaded end and it looks like a long elongated letter “U”.
The high-density elements are short-lived as they quickly attract limescale due to constant exposure to extremely high temperatures and hard water. Also, these types of elements quickly develop corrosion. 
- Low-Density Elements
Low-density elements provide good results in the process of heating, although still not ideal. They are usually made of copper, with a nickel or magnesium oxide coating.
These types of elements slow down the buildup of sediments, therefore prolonging their life. This means they are also less susceptible to corrosion.
When it comes to their shape, the low-density elements have parts that fold back and are also longer than high-density ones.
What also adds to their value is that they are less noisy than high-density ones.
- Ultra-Low Density Elements
These are the water heating elements of premium quality. Of course, this explains their price, as they are also the most expensive option of all 3.
The ultra-low density elements are usually made from stainless steel of very good quality. The quality is so good that some of them provide a lifetime long guarantee.
They are the most efficient ones, as they provide the best results. This also means that they are least prone to the buildup of limescale or corrosion.
Wattage of Water Heater Elements
The “density” we just discussed is linked to the wattage of the element in water heaters. In other words, density also means the amount of wattage per square inch on the surface area.
This rating of watts per square inch of surface is called watt density. 
The wattage of most water heater elements can range from 1500 to 5500 watts.
The wattage is linked to voltage, and both are printed on each element.
High-density elements have a high level of wattage per square inch, which is why they get super hot. In contrast, low-density ones don’t produce the heat that high per square inch, which is why they perform better.
The only difference between the same wattage elements in high and low-density elements is the surface area of the element.
Important advice to take note of:
- It is generally advised to match the voltage and wattage of the new elements.
- When buying a new element – keep volts the same, and…
- …buy the same or less wattage!
- Always match the volts of the element to the volts on the heater itself
So, if your question was – Can I replace a 4500-watt heater with a 3800-watt heater, now you know the answer. It’s totally fine to replace it with a lower wattage, as long as the voltage is the same.
Now you have the answer to the question – are water heater elements universal? Generally speaking, they are not, as there are many differences among them.
Here we presented some useful information about the differences in water heating elements you should look out for.
When buying new heater elements, pay close attention to the wattage and material of the element, as explained in this article. Choosing the right water heater elements will ensure proper installation, but also balanced and effective usage of hot water.