How to Remove Limescale from a Water Heater

How to Remove Limescale from a Water Heater

Cleaning limescale from a water heater can be a dirty job, and depending on the position of the heater in your bathroom, it can also be quite complicated. However, with a little bit of willpower and minimal tools, you can handle this task yourself. While the cost of cleaning limescale from a water heater or replacing the heating element isn’t high, prices can vary significantly between different professionals.

Limescale is one of the biggest enemies of water heaters. It forms as water heats up, accumulating most around and on the heating element. Even the smallest layer of limescale on the metal surface of the heater insulates it from the water, making it harder to transfer heat. Consequently, the water heater takes longer to reach the desired water temperature, leading to higher electricity consumption. This is particularly problematic since water heaters are known to be one of the largest electricity consumers in a household.

If You Don’t Want to Hire a Professional…

While it’s simplest to hire a good professional, be sure to get several quotes as prices can vary widely. If you don’t have anyone reliable or if you’re handy, you can perform this task yourself since the procedure is not overly complicated. Start with the basics: turn off the water heater and then switch off or unscrew the circuit breaker dedicated to the heater.

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After that, remove the bottom plastic cover and check with a voltage tester to ensure the heater is not live. Experienced professionals might find such thorough checks unnecessary, but when dealing with electricity, and especially if you lack experience, every precaution is worth taking.

Step-by-Step Guide to Removing Limescale

  1. Shut Off the Water Supply: Close the water supply valve to the heater and open the hot water tap, leaving it open. Move the cap on the safety valve located on the heater’s outlet pipe to allow the water to drain. This process is quite slow due to the small opening, but you can speed it up by removing the heating element while the heater is still full. This is particularly practical if the heater is located above a bathtub, as removing the heating element will create a large opening through which water and limescale will rush out.
  2. Protect Your Drains: During this procedure, it’s wise to plug the bathtub drain to prevent limescale from clogging it. From neglected large heaters, you might remove large amount of limescale; the quantities are not insignificant.
  3. Handle Electricity with Care: Before removing the heating element, disconnect the wires from its electrical contacts. If you’re not 100% sure which wire goes where, mark them with a piece of electrical tape or a marker. Also, detach the thermostat probes carefully, as these are thin copper tubes that can break easily.
  4. Remove the Heating Element: Unscrew the nut holding the heating element in place. Push the element into the heater’s interior, and once it dislodges, gently pull it out. If you’ve drained the heater through the safety valve, expect a little more water to flow out when the element is removed. If the heater is still full, be prepared for a strong jet of dirty water mixed with limescale. Ensure you don’t reach this stage with a heater full of hot water!

Dealing with the Limescale

You might be surprised at the amount of limescale at the bottom of the heater. Reach through the opening where the heating element was and remove all remaining limescale. If possible, rinse the interior of the tank with a hose. Carefully clean the heating element of limescale, but be cautious as it can be firmly attached.

Assess the condition of the heating element. If it’s old, consider replacing it with a new one. If it’s still in good condition, replace the elliptical sealing gasket before reassembling. Ensure the gasket seating area is free of limescale and dirt.

Reassembly and Final Checks

Reassemble everything in reverse order. Finally, open the valve to restore water supply to the heater. When the air stops escaping from the open hot water tap and the water flow stabilizes, the heater is full, and you can turn off the tap. Check for leaks around the heating element and tank junction, and perform another check once the water heats up and pressure increases.

How Often Should You Clean Limescale?

This procedure can vary slightly depending on the type and position of your water heater. A better question than “should you clean limescale from a water heater” might be “how often should you clean limescale from a water heater”. This depends on many factors, but in places with hard water, it’s good practice to do this annually or every two years. To reduce limescale buildup, one trick is to lower the water heater temperature to below 140°F (60°C), as less limescale forms at higher temperatures.

Photo: Tesy, Freepik

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