Best Electric Tankless Hot Water Heater (UK Review 2025)

Choosing the best electric tankless hot water heater isn’t just about lowering energy bills; it’s about adding convenience and reliability to everyday life. Modern models heat water on demand, free up valuable cupboard space, and eliminate the “someone used all the hot water” drama that many households know all too well. Here’s the best residential tankless water heater for modern homes. This unit heats instantly, saves space, and keeps everything running smoothly.

Exceptional

1. Stiebel Eltron DCE-X 10/12 kW Electric Tankless Water Heater

4.8 out of 5

• Power output: 10 to 12 kW
• Voltage: 220 to 240 V
• Display: Backlit LC control panel
• Installation: Oversink, compact design
• Weight: 2.5 kg

• PROS

• Provides steady hot water for daily shower routines.
• Maintains a consistent temperature even during quick flow changes.
• Saves space in small bathrooms or utility setups.
• Helps reduce energy use with its efficient control system.
• Responds quickly when you adjust the temperature settings.
• Works well for households needing reliable on-demand hot water.

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How does an electric tankless hot water heater work?

Electric tankless heaters operate on a simple flow-activated mechanism. When you open a hot tap or start an appliance requiring hot water, the unit detects water movement. It then switches on internal electric heating elements that rapidly heat the water as it passes through the heat exchanger.

Because the water is heated in real time, the system offers consistent hot water without the limitations of a tank running empty. Once the tap is turned off, the flow stops, and the heater automatically powers down. This makes the system energy-efficient and reduces standby heat loss; the energy wasted when traditional cylinders keep stored water hot even when it’s not being used.

What are the advantages of using an electric tankless hot water heater?

There are several notable benefits:

• Energy efficiency: Since the heater only operates when needed, it avoids the heat loss that comes with stored hot water, potentially lowering electricity bills.

• Space saving: Tankless units are compact and often wall-mounted, freeing up cupboard or utility room space.

• Continuous hot water: As long as the system is correctly sized, you won’t run out of hot water.

• Reduced risk of leaks: With no storage tank, the risk of tank-related leaks or corrosion is eliminated.

• Longer service life: Electric tankless systems generally last longer than traditional cylinders, due to fewer components vulnerable to wear.

These advantages make tankless heaters appealing for modern homes, smaller properties, or anyone aiming for energy-efficient upgrades.

Installation of an Electric Tankless Hot Water Heater

Installing an electric tankless hot water heater should always be carried out by a qualified electrician and plumber, as it involves both high-voltage electrical work and plumbing connections. Professionals will first assess the property’s electrical capacity, as many units require a dedicated high-amp circuit, and may check whether the consumer unit or wiring needs upgrading.

The installation process usually includes:

• Mounting the unit securely on a suitable wall.

• Connecting the cold-water supply and hot-water outlets with proper fittings and seals.

• Running a dedicated electrical supply that meets UK safety standards.

• Installing isolation valves, filters, or pressure regulators if required.

• Testing the system to ensure correct temperature, stable water flow, and safe operation.