How Does an Immersion Heater Work? | A&C Heating and Plumbing Ltd
An immersion heater is an electric device that heats water inside a hot water cylinder, making it an essential component in homes across North and West London, especially where gas boilers aren’t available. At A&C Heating and Plumbing Ltd, we often get asked how these systems operate and whether they’re still a good choice in modern homes.
Let’s explore how immersion heaters work, what types exist, and when you should consider installing or repairing one.
What Is an Immersion Heater?
An immersion heater is a metal heating element installed inside a hot water cylinder. It works much like a kettle – once powered, the element heats up and gradually warms the surrounding water in the tank.
Unlike gas systems, immersion heaters run entirely on electricity, and they can be operated manually, via a switch, or set on timers for maximum efficiency.
✅ Main Uses:
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Properties without gas supply
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Backup heating method
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Supplementary heating for solar or boiler-fed systems
Key Components of an Immersion Heater System
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Heating Element:
A resistive metal rod that produces heat when electricity flows through it. -
Thermostat:
Controls water temperature (usually between 55–65°C), shutting off the heater when the set temperature is reached. -
Timer / Controller (Optional):
Allows you to automate usage during off-peak hours (ideal for Economy 7 tariff users). -
Hot Water Cylinder (Vented or Unvented):
Stores heated water and supplies it to taps, baths, or showers.
Direct vs Indirect Heating
Understanding the difference helps you make better decisions about energy usage and system upgrades:
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Direct Systems:
The immersion heater is the primary source of hot water. -
Indirect Systems:
A boiler heats the water, but the immersion heater acts as a backup – useful if the boiler fails or for heating water in summer without firing the whole system.
How Does It Actually Work?
Let’s break it down step-by-step:
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You turn on the immersion heater or set the timer.
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Electricity flows through the heating element.
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The metal rod heats up and warms the surrounding water in the tank.
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The thermostat monitors the temperature and cuts off power once the desired temperature is reached.
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Hot water is stored in the cylinder and ready for use throughout your home.
💡 Tip: Use timers during off-peak hours to save on energy bills.
Are Immersion Heaters Efficient?
While immersion heaters aren’t as cost-effective as modern gas systems, they offer excellent reliability and flexibility:
✅ Great for electric-only homes
✅ Ideal backup during boiler breakdowns
✅ Easy to use with timers and thermostats
✅ Work well with solar PV diverter systems (for renewable energy)
📉 Downside: Electric heating is generally more expensive than gas – but smart controls can significantly reduce cost.
Common Issues With Immersion Heaters
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No hot water? May indicate a faulty thermostat or blown element.
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Water overheating? Thermostat failure may be the cause.
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Tripping fuses? Check for electrical faults or limescale build-up.
If you’re experiencing any of these, our team at A&C Heating and Plumbing Ltd is ready to help.
Do You Need an Immersion Heater?
Consider an immersion heater if you:
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Live in a property without mains gas
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Want a backup system in case of boiler failure
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Use Economy 7 or Economy 10 tariffs
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Have a solar PV diverter and want to utilise excess energy
Professional Immersion Heater Services in North & West London
At A&C Heating and Plumbing Ltd, we’ve helped homeowners in Islington, Ealing, Acton, Chiswick, Hammersmith, and beyond with immersion heater:
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🛠️ Installation
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🔧 Repair
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🧰 Maintenance
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🔄 System upgrades
We work with all types of cylinders (vented/unvented) and ensure your hot water is safe, consistent, and efficient.
📞 Call us today or book online for fast service from qualified engineers.
Areas We Serve Nearby
Our immersion heater services are available across North and West London, including:
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North London: Camden, Islington, Highgate, Finchley, Holloway
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West London: Ealing, Acton, Chiswick, Hammersmith, Shepherd’s Bush
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Surrounding areas: Harrow, Wembley, Kilburn, Brentford, Greenford
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Need Help With Your Immersion Heater?
Whether you need a new installation or troubleshooting, A&C Heating and Plumbing Ltd is your go-to heating expert in North & West London. Our engineers are fully trained, insured, and ready to restore your hot water quickly and safely.
📞 Call 0779 559 5757 or Book a Visit Online