Last Updated: February 17, 2026
An immersion heater is an electric heating element installed inside a hot water cylinder that heats water using electricity. In Dublin homes, immersion heaters are commonly used as a main or backup hot water system. Most units are 2–3 kW and include a thermostat to control temperature safely and efficiently. According to the Sustainable Energy Authority of Ireland (SEAI), maintaining correct thermostat settings and insulation can significantly reduce energy loss and running costs.
Introduction
If your immersion heater is not working, not heating water, or keeps tripping the fuse board, you’re not alone. Immersion heater repair in Dublin is one of the most common plumbing call-outs, especially in apartments and older homes.
At Dublin Plumber 24 hrs, we handle all types of immersion heater and control issues quickly and safely. Whether you need a new unit installed or your existing system repaired, our experienced team is ready to help across all Dublin areas, day or night.
What Is an Immersion Heater and How It Works
An immersion heater is an electric element fitted inside your hot water cylinder. It heats the water directly, much like a large kettle. The system usually connects to a timer or manual switch that controls when the heater turns on and off.
This setup is common in Dublin apartments and older homes that don’t use gas boilers. Modern models, including smart immersion controls, allow you to program heating schedules and boost functions to match your daily needs. Regular maintenance ensures your immersion heater runs safely and keeps energy costs low.
Why Is My Immersion Heater Not Working?
If your immersion heater is not working or not heating water properly, there are several common causes. Most problems are simple to diagnose once inspected safely.
Here are the main reasons we see:
Faulty Thermostat
If the thermostat fails, the heater may not switch on — or it may overheat and trip the fuse board.
Burned-Out Heating Element
In hard water areas, elements can corrode over time. The heater light may be on, but the water stays cold.
Tripped MCB or Fuse
If your immersion keeps tripping, there may be an electrical fault or internal short circuit.
Timer or Control Failure
Sometimes the heater itself is fine, but the timer or switch has failed. If it’s not turning on at set times, the controller may need replacing.
Loose or Damaged Wiring
Immersion heaters draw high power (2–3 kW). Worn wiring or poor connections can stop the unit from working safely.
Low or Empty Cylinder
The element must always be fully submerged in water. If the cylinder is empty or airlocked, it won’t heat properly.
If you’re unsure what’s causing the issue, it’s best not to attempt DIY electrical repairs. A quick inspection can usually identify the fault and restore your hot water the same day.
Immersion Heater Controls and Timers Explained
Your immersion heater’s controls decide when the element heats and for how long. A reliable timer keeps water hot when you need it and saves energy when you don’t. Many homes still use manual switches, but upgrading to a modern immersion heater control can make a big difference.
Here’s why:
✅ Flexible scheduling — Set up to three heating periods per day (24-hour, 5/2 day, or 7-day programs).
⚡ Boost mode — Choose 30-minute, 1-hour, 2-hour, or 3-hour boosts for quick hot water without wasting power.
💡 LED indicators — Clearly shows when the heater is active or in boost mode.
🔒 Built-in safety — Overheat protection helps prevent electrical faults or overheating.
🔌 Supports single or dual elements — Works with standard 3 kW immersion heaters common in Dublin homes.
🕒 Energy efficient — Digital control reduces unnecessary heating and lowers running costs.
The EPH IMC digital immersion controller is one of the most popular and reliable options in Ireland. It’s easy to use, fully compatible with Irish electrical standards, and helps households manage hot water more efficiently.
If your immersion timer is worn out, unresponsive, or always left on, we can replace it with a safe, programmable controller that saves energy and keeps your water heating system running smoothly.
How Much Does an Immersion Heater Cost to Run in Ireland?
Immersion heaters are powerful electric appliances, so understanding the running cost is important — especially with rising electricity prices in Ireland.
Most standard immersion heaters are 3 kW units.
This means they use 3 units (kWh) of electricity per hour when actively heating.
Example Running Cost
If the average electricity rate in Ireland is around €0.30–€0.40 per kWh, then:
1 hour of use = 3 kWh
3 kWh × €0.35 (average rate) = approximately €1.05 per hour
If left on for 2 hours per day, that could cost over €2 per day, or more than €60 per month, depending on usage and tariff.
Why Using a Timer Matters
Leaving an immersion heater on constantly can significantly increase electricity bills.
A programmable timer helps by:
Heating water only when needed
Preventing overnight waste (unless using night-rate electricity)
Reducing unnecessary reheating cycles
Extending the lifespan of the heating element
In many Dublin homes, upgrading to a digital immersion controller can noticeably lower running costs over time.
When to Call a Plumber for Immersion Heater Repair
Some immersion heater issues can seem minor at first, but they often point to deeper electrical or mechanical faults. If you notice any of the following, it’s best to call a professional rather than risk damage or safety hazards:
🚫 No hot water at all – The heating element or thermostat may have failed.
🔥 Water too hot – A broken thermostat can cause overheating and wasted energy.
⚡ Tripped fuse or power light off – Usually indicates an electrical fault.
💧 Strange smells or sounds – Could mean burning insulation or limescale buildup.
⏰ Timer not switching on or off – Control panel or wiring fault that needs safe replacement.
At Dublin Plumber 24 hrs, our Fully insured, experienced, and qualified plumbing team has over 24 years of experience handling immersion heater repairs across Dublin. We carry replacement thermostats, heating elements, and control timers for quick same-day fixes.
How to Maintain Your Immersion Heater
A little care can make your immersion heater last years longer and work more efficiently. Regular maintenance also helps avoid costly repairs or energy waste. Here are a few practical tips:
🔌 Switch it off when not needed – Leaving it on constantly wastes power and can overheat the element.
💧 Check for limescale buildup – Dublin’s hard water can cause scale on the element; descaling once a year helps.
🌡️ Inspect the thermostat – If your water is too hot or too cold, it might need recalibration or replacement.
🔋 Use the timer smartly – Program heating times around your routine to avoid unnecessary electricity use.
🧰 Annual service – Have a qualified plumber check wiring, insulation, and safety features once a year.
These small steps help extend the lifespan of your immersion heater and keep your hot water system running smoothly.
Immersion Heater Repair & Replacement Cost in Dublin
The cost of immersion heater repair in Dublin depends on the type of fault, the condition of the wiring, and whether parts need replacing. Most issues can be resolved quickly once the system is safely inspected.
Here’s a realistic guide for Dublin homeowners:
Immersion element replacement: €180–€250
Thermostat replacement: €120–€180
Full immersion heater replacement: €250–€350
Digital timer or control upgrade: €120–€180 (including fitting)
Most repairs take between 1–2 hours, and we carry common parts for same-day service.
We always provide a clear quote before starting work — no hidden call-out fees and no unexpected charges. Every immersion heater repair or replacement in Dublin includes proper testing, safe electrical isolation, and full compliance with Irish standards.
FAQ – Immersion Heater Help for Dublin Homes
How much does it cost to replace an immersion heater in Ireland?
The average cost to replace an immersion heater in Ireland ranges from €250 to €350, depending on the element type and wiring condition. A simple thermostat or element replacement may cost less, typically between €120 and €250. Installation usually takes 1–2 hours.
How much does it cost to run an immersion heater for 1 hour?
Most immersion heaters are 2–3 kW.
At an average Irish electricity rate of around €0.35 per kWh, running a 3 kW immersion heater for one hour costs roughly €1.05.
Using a timer or boost function helps reduce unnecessary running time and lowers energy bills.
Do I need a plumber or electrician to replace an immersion heater?
An immersion heater involves both plumbing and electrical connections. In most Dublin homes, a qualified plumber experienced with immersion systems can safely replace the element and thermostat. If major rewiring is required, an electrician may also be needed.
Does an immersion heater use a lot of electricity?
Yes, immersion heaters are high-energy appliances because they heat water directly using electricity. However, they are efficient when used correctly with proper insulation and a working thermostat. Leaving the immersion heater on constantly will increase electricity costs significantly.
Is it cheaper to leave an immersion heater on all day?
No. It is generally more expensive to leave an immersion heater on all day. Heating water only when needed — using a timer or short boost setting — is far more energy efficient and reduces electricity bills.
How much does a 10-minute shower cost in Ireland?
If your hot water is heated by an immersion heater, a 10-minute shower can cost approximately €0.80–€1.20, depending on electricity rates and water temperature settings. Good cylinder insulation helps reduce reheating costs.
What is the simplest way to reduce immersion heater running costs?
The easiest ways to cut costs are:
Use a programmable timer
Set the thermostat to around 60°C
Insulate your hot water cylinder
Avoid leaving the immersion heater switched on continuously
These small changes can noticeably reduce your electricity bill over time.
Call Dublin’s Trusted Experts Today
If your immersion heater isn’t heating properly, runs constantly, or needs a new timer, our team is ready to help. At Dublin Plumber 24 hrs, we’ve spent over 24 years repairing, replacing, and upgrading immersion heaters across Dublin.
We’re fully insured, RGI-certified, and available 24/7 — so you’ll never be left without hot water. Whether it’s a faulty thermostat, a new EPH control installation, or a full immersion heater replacement, we’ll get it sorted quickly and safely.
📞 Call or WhatsApp us today for a fast quote and same-day service.
Reliable. Local. Professional — that’s Dublin Plumber 24 hrs.