Elementary, Watson: Water Heater Element Selection 101

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Electrical rating, watt density, and anchor / flange are the factors to consider to replace a water heater heating element. Standard dual-element elements are rated 240V; wattage varies with capacity, typically from 1400 to 5500 watts. Replacing an element with a higher wattage element is unsafe.

My friends think I’m an expert when it comes to electric water heaters, so I wasn’t too surprised when one of them called to say that she needed help figuring out what kind of a heating element she should buy for her water heater. She’d gotten a neighbor’s help with getting the busted upper heating element out. But then he’d had to leave in a hurry, and now she was stuck.

After I’d walked her through the process, I thought I’d put down some notes that might be helpful to someone else in a similar situation.

The four important factors in selecting a heating element for an electric water heater are, (1) its electrical rating (in watts and volts), (2) anchor type (screw-in vs. bolt-in), (3) flange type for bolt-in elements, and (4) watt density (heat yield per unit surface area, or watts per square inch). 

Before getting into choosing heating elements, though, it’s important to establish whether the old one is, in fact, busted. After all, replacing the heating element isn’t going to resolve your hot water crisis if it had nothing to do with the element in the first place!

Has the Heating Element Really Stopped Working?  

Let’s begin at the beginning. Your water heater’s not producing any hot water. Or, it’s not producing enough. Or maybe, the water’s not hot enough. There could be several reasons for this, including:

  • Thermostat setting too low. To adjust this, use a flat-blade screwdriver to turn up the temperature setting on the white plastic dial, usually located behind the access panel. (The recommended thermostat setting is typically between 110 °F and 125 °F.)
  • Water heater tank too small. (Rule of thumb: A 30-gallon tank will serve two people, a 50-gallon should work for four, but for a larger family of say, six or seven, an 80-gallon would be a safe bet.)
  • Malfunctioning lower heating element due to build-up of calcium deposits. (Experts recommend flushing calcium deposits out of your water heater once a year. For dos and don’ts that make DIY calcium deposit removal really simple, check out this post.)
  • No electricity supply to one or both heating elements. (The ‘Reset’ button below the thermostat may have popped due to overheating of the tank. If pressing the Reset button and turning the water heater power back on causes the circuit breakers to trip again, there’s likely to be a short-circuit, for example, because of improper ‘grounding’, see below.)
  • One or both heating elements busted. This means that they’re either not allowing electricity to pass through (check this through a continuity test), or because of ‘grounding’, which is a short-circuit carrying electricity to the metal parts of the water heater (check this through a grounding test).

In addition to the heating elements themselves, be sure to check if the associated thermostats are functioning.

For more help on troubleshooting grounding, check out our helpful guide on water heater wiring.

Now you’ve eliminated other possibilities, and zeroed in on the heating element as the cause of the problem. You’re still left with choosing a replacement that would work with your water heater, as well as being able to meet your hot water requirements.

Selecting the Right Heating Element

You probably already know that a heating element is not that expensive… you could buy one of them on Amazon for the price of a shower curtain liner! So, what’s the big deal? Why’s it important to figure out exactly what kind of element you do need?

The wrong heating element could lead to range of problems, from the relatively minor, like an extra trip to the store, to the more serious, like permanent damage to the water heater, or even a fire hazard.

So, take a minute to read carefully through the following section, which outlines the important points you need to consider when choosing a new element for your electric water heater.

The Four Most Important Aspects to Consider When Choosing a Heating Element

1. Electrical Rating

The most important thing to verify is the electrical rating for the new heating element. Unless you’re looking at a compact water heater (the under-the-kitchen sink kind), which typically has a single, 120V heating element, you’re likely dealing with a standard, dual element water heater whose elements have voltage ratings of 240V.

Also make sure of the wattage rating of the heating element (for example, 4500W). Both voltage and wattage ratings are usually embossed on the element casing.

A new heating element with an identical wattage rating as the old one will make no difference to how the circuit functions, but changing the wattage will. If you install a new element with a higher wattage (say, 5500W in place of 4500W), it will try to draw more electricity than the circuit is likely set up for, leading to overheating and possible damage to the water heater itself, in addition to being a fire hazard.

On the other hand, a lower wattage rating (say, 3500W to replace a 4500W element) is likely to last longer, but on the flip side, it’ll take longer to heat water to the required temperature.

Tip 1: If you’ve gotten rid of the busted heating element, don’t worry. Simply check your water heater’s power rating label, where it says ‘Upper Heating Element’ and ‘Lower Heating Element’ to find out its wattage rating. (For help on finding the power rating label on your water heater, check out this super-helpful post.)

Tip 2: One hack for saving $$$ on elec bills is to switch out the original lower heating element with a new one rated for a lower wattage (say, 3500W instead of 4500W). Remember, the upper heating element comes on first, and heats the water in the upper half of the tank. And, you usually only need a limited amount of water in a hurry (for example, just enough for a shower).

2. Element Anchor Type

Does the original heating element have screws or bolts anchoring it to the water heater? Due to their greater ease of operation, nearly all newer water heater models have screw-in elements. But if your water heater is older, say, ten or more years old, you might have one with a bolt-in mechanism for anchoring the heating elements. 

While an identical replacement might be hard to find, it’s simple enough to get an adapter kit that will enable you to install a screw-in heating element in place of the old bolt-in that came with your water heater. Just be sure to find an adapter kit that is compatible with your new heating element and the flange type of your old element. (For example, check out the Camco and Reliance universal adapter kits available on Amazon.)

3. Element Flange Type (for Bolt-in Heating Elements)

As described above, older models of water heaters often have bolt-in heating elements, usually with a system of four bolts on a flange to anchor the element to the heater body. Unfortunately, instead of a single, standard design, these flanges come in a variety of shapes, including the round-head, square and hexagonal styles.

So whether you’re determined to replace your old, bolt-in heating element with an identical one, or if you want to use a screw-in type with an adapter kit, make 100% sure that you get a replacement that will work.

4. Heating Element Watt Density

You know that the heating element is putting out heat inside your water heater, which is how the water heats up. Not all heating elements put out the same amount of heat per square inch, which is why the ‘watt density’ of the element becomes important.

Heating elements of low versus high watt density put out different amounts of heat per square inch of surface area. The greater surface area of a low-watt-density element allows it to heat water to required levels, but without getting as hot as a high-watt-density element, thus lasting longer.

Most water heater manufacturers put in high-watt-density elements that are cheaper, but don’t last as long. These are easy to identify, owing to their elongated, U-shaped appearance. Lower density elements usually have a ‘fold-back’ design, wherein the heating coil is much longer than in a U-shaped element.

In recent years, heating elements with a ‘ripple’ design have appeared on the market, which boast ultra-low density, resistance to limescale build-up, and even immunity to dry firing (burnout of heating elements that occurs when someone turns on the water heater power without making sure it’s full of water). Foldback and ripple style heating elements are especially recommended for areas with ‘hard’ water supply, which is high in mineral content.

I hope these pointers have simplified picking out a suitable heating element for you as much as it did for my friend.

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