You can independently find a suitable model using the general catalog of water heaters, which provides an abundance of selection parameters.

How a water heater works: the basics

The design of contemporary water heaters is largely standardized. The reliable and relatively simple operational scheme has demonstrated its effectiveness in practice, so any alterations, if they occur, are typically minor and may only involve specific aspects or minor details.

Since the water heater is a storage type heater, its constant component is a water tank. Today, this tank, as a rule, provides additional insulation and is actually a large-volume thermos, that is, it not only heats the liquid, but also tries to keep it warm longer.

At the bottom of the tank, where water flows from the cold water supply system, there is a heating element. Today, in 99% of cases this is a heating element (tubular electric heater), which previously had an alternative in the form of coils. But the latter are actively used only in flow-through devices. The heating temperature is controlled by a thermostat, which turns the heating element on and off as needed.

The laws of physics are responsible for the movement of cold and warm water inside the water heater tank. Thus, hot liquid has a lower density and therefore tends to rise up the tank. From there, it is directed to fulfill our requirements - whether in the shower, kitchen, or other other taps. Furthermore, storage water heaters offer a range of automation options, including Wi-Fi connectivity for remote control via the Internet, security features, and magnesium anodes to safeguard the metal parts of the appliance against corrosion.

A water heater is not as complicated a device as it might seem.

Previously, even heating elements for water heaters were mostly the same. But now the user can choose between so-called “wet” (open) and “dry” (closed) heaters. In fact, this is the main dilemma that you need to deal with before purchasing, if you have already decided on the appropriate tank volume.

“Wet” heating element: design features, pros and cons

Chronologically, water heaters equipped with “wet” type tubular heaters appeared earlier, so we’ll start with them. This heating element consists of:

  • heating element filaments to which electric power is supplied;
  • filler. This component is dielectric, that is, it does not conduct power, but has high thermal conductivity. The filler can be magnesium oxide or quartz chips (sand);
  • metal tube — most often copper, because this material transfers heat well (compared to steel).
A wet heating element is in constant contact with water.

How does a "wet" heating element operate? The heating element of water heater is typically permanently installed within the tank and remains in direct contact with the liquid. This heater copes well with its tasks, but is sensitive to water quality. If it is hard, then scale will inevitably appear during the heating process. The corresponding deposits gradually coat the metal tube, reduce its thermal conductivity and increase the risk of overheating of the heating element (especially if there is no special protection). As a result, the overall efficiency of the water heater decreases, and the heating element may break.

If a wet heater is not properly maintained, there is an increased likelihood of water leakage (through a damaged heating element) and insulation breakdown, in addition to heater failure itself. The risk of electric shock during operation of modern water heaters is often exaggerated. Firstly, there are enough models on sale with built-in RCDs. Secondly, similar electrical protection components are increasingly being provided at the stage of renovation in apartments or houses. Although if the water heater and wiring are dilapidated, then a similar problem due to a “wet” heating element is still relevant.

Water heaters with “wet” heating elements

The main advantages of open type heating elements:

  • low cost (of the heater itself and, accordingly, the water heater with it);
  • wide range and versatility — when replacing an original heating element, it is often not necessary to consider only spare parts of the same brand;
  • balanced performance characteristics, especially subject to maintenance regulations or ensuring water softness (for example, through filters for purifying hardness salts).
Without maintenance, a wet heating element actively becomes overgrown with scale.

The main disadvantages of a “wet” heating element:

  • susceptibility to scale formation;
  • less reliability than its “dry” counterpart;
  • not only maintenance, but also replacement of the heating element requires draining the water from the tank;
  • there is a risk of insulation breakdown (due to damage to the heater insulation).

Keep in mind that scale not only negatively affects the service life of the heating element (it eventually destroys the metal and provokes corrosion processes), but also increases energy costs. A scale-covered heating element has to operate longer to reach high water temperatures and the user has to overpay for electricity.

To minimize the main disadvantage — the scaling factor — modern "wet" heaters can be coated with enamel or other materials that better resist hardness salts.

“Dry” heating element: design features, pros and cons

The "dry" heating element is hidden under a metal flask.

The design of the closed heating element prevents its direct contact with water. How exactly is this implemented? The heating element in the tank is located inside the flask. The latter, as a rule, is made of steel and may have additional coatings (enamel, ceramics, etc.). The flask is heated indirectly — through air or other materials, for example, oil (as in oil radiators) or quartz sand. Not so high temperatures and a metal more resistant to hard salts reduce the intensity of scale formation. At the same time, problems with performance (the rate of heating of the liquid) usually do not arise, because the presence of the flask increases the heat transfer area several times.

Water heaters with a “dry” heating element

"Dry" heating elements come in many forms. The most budget options assume that one or more copper tubes are installed inside the rod flask. As a result, the differences from the usual "wet" analogs are insignificant. The closed design increases the level of protection of the heating element (and also almost eliminates current breakdown), but the flask still forms deposits quite actively.

A more efficient design of “dry” heating elements involves the presence of an interlayer material with high thermal conductivity (like oil) or comes down to the complete abandonment of classic metal tubes. For example, the Atlantic manufacturer uses Steatite technology — the coil is coated with the mineral steatite, which efficiently gives off heat. Due to such solutions, heat losses are reduced, deposits are formed more slowly, so this part requires less frequent maintenance.

A dry heater may often have no metal tube at all.

The main advantages of “dry” heating elements include the following:

  • less susceptibility to scale formation, which means minimal requirements for water quality;
  • increased service life compared to analogs and often reduced frequency of maintenance;
  • the risk of insulation breakdown tending to zero — in theory, this is possible if the flask is destroyed due to corrosion processes, but the tank is more likely to leak;
  • the ability to replace the heating element without draining the water.

Disadvantages of a closed tubular heater:

  • higher cost of spare parts (and the water heater itself);
  • exclusivity of parts. As a rule, a specific brand and model of heating element is required for replacement.

Maintaining a water heater equipped with a "dry" heating element typically entails extracting the tank and descaling it, a service usually required less often. Sometimes, this may align with the same yearly schedule as "wet" counterparts, but in certain cases, it can extend up to 5 years. In the latter scenario, servicing the heating element coincides with replacing the magnesium anode. These tasks necessitate draining the water from the tank.

It is also worth noting that previously water heaters with two heaters were exclusively models with “dry” heating elements, but now the situation has changed. On sale today you can find devices that have several open copper tubes inside the tank.

Water heaters with 2 heaters

What is better — open or closed heating element?

Before drawing conclusions, we recommend comparing the main common and distinctive features of heating elements of modern water heaters. The relevant information is presented for you in the table:

Comparison factor "Wet" heating element "Dry" heating element
Water heater price lower higher
Reliability lower higher
Requires maintenance once a year yes less often
Whether to drain water for maintenance? yes yes
Whether to drain the water to replace the heating element? yes no
Demand for original spare parts lower higher
Can there be two heating elements in one water heater? yes yes

If the water is hard, the right choice today is, of course, a water heater with a "dry" heating element. The overpayment for it compared to an analog with a “wet” heating element will be lower than the additional costs for installing flow-through filtration systems.

If you have a limited budget, you can choose a model with an open heater. However, if you expect a long service life from this product, we recommend you strictly follow the manual and perform regular maintenance.

Regardless of the type of heating element, it is recommended that the water heater be maintained.

If you follow the manufacturer's recommendations, an open heating element lasts on average from 5 to 10 years, and a closed one — from 15 years. But also a lot depends on the status of the brand, the stability of the voltage in your electrical network, other variables (quality of water, etc.).

It's important to mention a caveat noted by some water heater repair experts. The benefits of "dry" heaters may become less apparent if the customer neglects recommended maintenance entirely. In such cases, a quick buildup of scale on a "wet" heater could be seen not just as a disadvantage but potentially advantageous. While the heating element may fail, repairing it allows the water heater to resume its function of providing hot water. Typically, the heating element's tube suffers from scale immediately after the magnesium anode fails, as copper is the softest metal inside the tank. A failure of the "wet" heating element necessitates contacting repair specialists who will replace the magnesium anode and the heating element (which isn't typically an expensive part). Additionally, during servicing, the tank walls are usually descaled, likely remaining intact.

Water heaters with magnesium anode

But with this approach there is a risk that the heating element will not be the worst problem, but the walls of the tank, and if scale destroys them, you will have to buy a new appliance — repairing it will not help. In a sense, a water heater with a "wet" heating element seems to be a better option if you disregard the manufacturer's recommendations on maintenance procedures.

Otherwise, a water heater with a “dry” heating element is considered more technologically advanced, reliable and versatile in relation to water quality.