Immersion Heater Is Not Working

immersion heater

You are feeling excited and well deserved after a day of hard work. It can be frustrating when the hot water tap only lets out a small amount of warm water! If you have to wait a long time to get hot water, you have some issues in the system.

You are wondering why my immersion heater is not working? The likely causes of immersion heater issues may be anything from a limescale buildup to a faulty thermostat.

Is your hot water not reaching the temperature you expect it to? Then read on for insight into what could be causing this issue. We will give you a few tips on what can you look out for.

Why do I have cylinder immersion heaters?

The old water heater that used a gas burner to warm the water was replaced with a storage tank and immersion water heater together.

First, you should have a hot water cylinder in the airing cupboard or the loft. Inside the storage tank, you can find cylinder immersion heaters. You can have two immersion heaters or gas water heaters here, one at the top and one at the bottom. The immersion heater is heating your water inside the steel tank providing you with hot water. The immersion heater replaces the gas water heaters, which are not manufactured anymore.

The upper heating element of a hot shower is just for a boost. You can turn it on and you will receive hot water in a hot shower in less than 10 minutes.

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How does my heating element work?

heating element

The immersion heaters are heating the cylinder directly with heated water. In simple terms, this process means that the element is slid inside the water tank.

The upper heating element is a small metal coil that is inside the cylinder. An electric current will pass through this thin wire. The upper heating element will heat the water.

Your kettle in the kitchen is a heater not work the same as an immersion heater in the cylinder. The water heater is working the same too.

The immersion heater is connected to the main electrical supply through an isolating switch that you can find next to the cylinder. You can turn on and off the cylinder with a switch. The electricity flowing through this wire will be heating the heating element which heats the hot water.

Also, you can find internal or external thermostats and internal safety devices, this can be either an internal or external thermostat that regulates the water temperature.

How do I get hot water?

When you use your hot water, you open the tap and the hot water starts to flow out. Meantime the cold water (what should be high pressure) will enter the cylinder. This will push out the hot water from the tank, thus you have good pressure and steady flow at the taps.

When you use a lot of water the temperature in the cylinder drops. The thermostat will sense the drop and turn on the immersion heater heating your water.

The process between the hot and cold water mixing in the cylinder is the following:

When the hot water heats up, it will start to rise to the top of your cylinder, leaving the cold water at the bottom. This heated water then will flow out to your taps.

Make sure your cylinder temperature is set to at least 55°C so you can avoid legionella bacteria.

Read more about how can you avoid the dangerous legionella bacteria in your storage tank.

My immersion heater stopped working

The reason behind this can be a few things. Limescale build-up can be an issue. Or the constant use of the immersion heater. If you have also a gas boiler that heats your cylinder, try to use that instead. The immersion heater consumes a lot of electricity.

The average immersion heater will last up to 6000 hours. Manufacturers will give a 5-year warranty. But most of the storage tanks in the UK are over 20 years old.

Why is my immersion heater not working?

The most common Immersion Heater Faults

In the next few minutes, we explain the most common problems that can cause the immersion heater to fail. But remember not to carry out any work if you are not competent or not confident. We will explain how to investigate the source of your problem starting with the basics of two immersion heaters and heater faults.

1. Check if your circuit breaker tripped

circuit breaker

For the immersion heater heating part to work, it needs electrical power. If there is a power outage there is no power going to the heating element there will be no hot water supply. The immersion heater’s electrical panel breaker could be tripped.

This is to protect your circuit from overloading. If your circuit overloads this can cause a fire.

All you have to do is go to the electrical panel check if the breaker is tripped and turn it back on. If you are lucky it could work again. But if not then you have an issue with the main breaker panel or the heating element.

If you are an advanced DIY homeowner, you can test if the immersion heater has a 220-240 volt supply.

If you start to work on wiring any electrical device, first turn off all electricity except the circuit breakers, remove the immersion heater plastic top and don’t touch any wiring. After you remove the lid, turn back on the power and check if there is 240 Volt.

Stay safe, stay alive. Do not rush.

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Read our guide about how an immersion heater can be tested.

2. Faulty thermostat

immersion heater thermostat

If you start to investigate the fault, turn off the power first. On some systems, there should be a red reset button on the thermostat that you can press. This will restart your immersion heater and everything will be back to normal.

If you have an older system the steps are the following:

Switch off the circuit breaker in your electrical panel.

On the immersion heater, there is a plastic cover which you have to remove.

Do not touch any wire with your bare hand!

On the thermostat, you can press the simple reset button. This could be a small round red button.

Put back the plastic cover and check the system by turning on the power.

If it’s still not working, you can change the thermostat yourself after you check there is no power going into it with a voltmeter. But if it heater not working and you are not confident to do so book one of our professional plumbers who can investigate the fault.

3. Your heating elements are damaged

You can’t investigate your fault yourself but just think about the past week’s cylinder performance.

Does the storage water tank take a while or quick to heat up? Usually, a 150-litre cylinder would take between 1-3 hours to heat up.

What is happening here, is that the element inside the cylinder is corroded. It will still survive a few weeks, but the water will leak inside when a hole appears on the element. In a case like this, the element will turn trip the circuit breaker.

We do not encourage you to change or replace the wiring or any faulty elements. Only a professional plumber or brave electrician can do this work.

This is serious plumbing work involving closing the water that supplies the tank. Draining down the cylinder and taking out the immersion heater with special tools. Also, if an airlock builds up in the pipes, the plumber can deal with that and know how to resolve the upcoming situation.

Even for a professional plumber is hard work, because sometimes the immersion heater is not moving.

Also, it can happen while the plumber taking out the immersion heater the cylinder can crack and this needs replacing. This is a rare occasion, but if the cylinder is over 30 years old it could happen.

4. Limescale inside your cylinder

This could happen in hard water areas. And we can say that part of North London is falling into this category.

If limescale builds up in your water tank, this can damage the water heating the element and also you can have less water in the tank.

Again, only a very professional technician or plumber can clean out a cylinder. For this work, the cylinder needs to be washed with a high-pressure jet.

The best way to avoid limescale buildup is to call a plumber who can install a limescale reducer. This reducer will be installed onto the cold water pipe before the cold water enters the cylinder.

Cylinder Insulation

hot water cylinder insulation

The insulation is not a fault, but it can reduce heat loss. But if the insulation starts to come off from the water heater then the cylinder will take double the time to heat up. And even after the cylinder heats up, will lose a lot of heat because of a lack of insulation.

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Do you have hot water by now?

Don’t let a malfunctioning immersion heater dampen your day! Give us a call and we’ll fix it in a flash!

We hope by now, you know the basics of how to investigate some of the most common issues with immersion heater faults. If you still don’t have any success contact us today for advice! Our expert plumber will help you sort out your problems.

Frequently asked questions about immersion heater faults

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