Best under sink instant hot water Heater UK
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4 Best Under-Sink Instant Hot Water Heaters in the UK

✓ Reviewed by the Ultimate House Team

Top-Rated Under-Sink Instant Hot Water Heaters

An under-sink water heater can provide hot water directly where you need it, without relying on a long pipe run from a central boiler or cylinder. These compact units are particularly useful for kitchens, utility rooms and other sinks where space is limited. We’ve selected models with practical sizes, useful temperature controls and straightforward installation in mind.

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01 · Best Overall

COMFEE’ 10L Undersink Electric Water Heater

4.8/5

Excellent

KEY DETAILS
Capacity: 10 litres | Power: 2kW | Energy class: A | Power source: Corded electric | Dimensions: 32.4W x 32.4H cm | Tank protection: Ti+ SapphirEnamel | Protection: Dry combustion and overheat protection | Insulation: Polyurethane foam

The COMFEE’ is a compact 10-litre storage water heater designed for installation beneath a sink. Its 2kW heating system, Energy Class A rating and insulated tank make it suited to small households needing readily available hot water in limited spaces.

WHAT WE LIKE

  • 10-litre capacity suits everyday sink use in smaller households
  • Energy Class A rating helps limit electricity consumption
  • Compact design makes use of restricted under-sink cupboard space
  • Ti+ SapphirEnamel coating helps protect the tank from corrosion
  • Polyurethane insulation helps slow temperature loss between uses
CHECK PRICE ON AMAZON UK

02 · Best for Larger Water Capacity

Ariston Andris R 15 Litre Undersink Electric Water Heater

4.7/5

Excellent

KEY DETAILS
Capacity: 15 litres | Power: 2kW | Energy class: B | Power source: Corded electric | Dimensions: 34.6W x 38.5H cm | Tank: Titanium enamelled | Control: Immersion thermostat | Insulation: High-density polyurethane

The Ariston Andris R provides 15 litres of stored hot water in a compact under-sink format. It has a 2kW heating element, titanium enamelled tank and adjustable thermostat, making it suitable when a little more stored capacity is useful for regular sink use.

WHAT WE LIKE

  • 15-litre capacity provides more stored water for repeated use
  • 2kW heating element provides a practical level of power
  • Titanium enamelled tank is designed to resist corrosion
  • Immersion thermostat allows precise temperature adjustment
  • High-density polyurethane insulation helps reduce heat losses
CHECK PRICE ON AMAZON UK

03 · Best Budget

Litglobe 10L Electric Water Heater

4.6/5

very good

KEY DETAILS
Capacity: 10 litres | Power: 1.5kW | Dimensions: 26W x 28H cm | Colour: White | Display: LED digital display | Control: Temperature adjustment knob | Protection: Automatic pressure relief | Dry-burning protection: Yes

The Litglobe is a compact 10-litre electric storage heater intended for under-sink installation. Its LED display and temperature control knob make the settings easy to monitor, while automatic pressure relief and dry-burning protection provide additional safety features.

WHAT WE LIKE

  • LED display makes the current temperature easy to monitor
  • Temperature knob provides straightforward control over water temperature
  • 10-litre tank offers useful stored capacity beneath sinks
  • Automatic pressure relief helps protect against excessive pressure
  • Compact dimensions suit kitchens and other restricted installation areas
CHECK PRICE ON AMAZON UK

04

thermomate ET055 5.5kW Instantaneous Water Heater

4.6/5

very good

KEY DETAILS
Power: 5.5kW | Flow rate: 3 LPM | Power source: Electric | Dimensions: 37W x 18H cm | Display: LED | Installation: Under or over sink | Protection: Overheat and dry-burning protection | Connection: G1/2″

The thermomate ET055 is an instantaneous electric water heater that heats water as it is needed rather than storing it in a tank. Its 5.5kW heating system, 3 LPM flow rate and compact design make it suited to point-of-use applications around sinks.

WHAT WE LIKE

  • Instantaneous heating avoids maintaining a tank of stored water
  • 5.5kW power rating supports on-demand point-of-use heating
  • Compact 18cm width can help where cupboard space is limited
  • LED display provides convenient temperature information during use
  • Can be positioned either above or below the sink
CHECK PRICE ON AMAZON UK

05

GEESEN 10L Electric Water Heater

4.5/5

Good

KEY DETAILS
Capacity: 3.5 gallons | Power: 2kW | Power source: Corded electric | Dimensions: 25W x 35H cm | Material: Stainless steel | Control: Adjustable thermostat | Protection: Overheat protection | Maintenance: Built-in drain valve

The GEESEN is a compact point-of-use storage water heater with stainless steel construction and an adjustable thermostat. Its 2kW power rating, compact dimensions and built-in drain valve make it suitable for installations where accessible hot water and straightforward maintenance are priorities.

WHAT WE LIKE

  • Stainless steel construction provides a durable outer build
  • Adjustable thermostat allows the water temperature to be set
  • Built-in drain valve simplifies draining during maintenance
  • Compact dimensions make it suitable for restricted spaces
  • 2kW power rating keeps the electrical requirement relatively modest
CHECK PRICE ON AMAZON UK

Buying Guide & FAQ

Factors to Consider When Choosing a Heater

Capacity and Flow Rate

When selecting an under sink instant hot water heater, consider the capacity and flow rate. The capacity will determine how much hot water the unit can supply at once, while the flow rate will affect how quickly the water is heated. Choose a model that matches your household’s hot water demands to ensure a consistent supply.

Temperature Control

Some models come with adjustable temperature controls, allowing you to set the water temperature to your preference. This feature can be particularly useful in households with different needs, ensuring everyone can access hot water at their desired temperature.

Safety Features

Safety is a crucial consideration. Look for models with features such as automatic shut-off, thermal cut-off, and temperature control to prevent overheating and ensure safe operation. These features can help prevent accidents and protect both the appliance and the user.

How to install instant hot water heater under sink: Step-by-Step Installation

  1. Prepare the Area

    • Turn off the water supply to the sink.
    • Clear out the area under the sink for easy access.

  2. Mounting the Heater

    • Choose a suitable location under the sink for mounting the heater, ensuring it’s close to the water supply and power outlet.
    • Use the mounting brackets provided to secure the heater to the wall or cabinet.

  3. Connect Water Supply

    • Identify the cold water line under the sink.
    • Install a T-joint valve on the cold water pipe.
    • Connect the cold water inlet of the heater to the T-joint using appropriate fittings and Teflon tape to secure the connections.

  4. Install the Faucet

    • Attach the hot water outlet of the heater to the faucet using the provided fittings and Teflon tape.
    • Ensure all connections are tight to prevent leaks.

  5. Electrical Connections

    • Follow the manufacturer’s instructions for electrical connections.
    • Typically, this involves connecting the heater to a dedicated power outlet.

  6. Testing

    • Turn on the water supply.
    • Plug in the heater to the power outlet.
    • Open the faucet to allow water to flow through the heater.
    • Check for leaks and ensure the water heats up as expected.

  7. Final Checks:

    • Tighten any connections if necessary.
    • Ensure the heater is securely mounted and stable.
    • Test the heater a few times to ensure consistent operation.