Water heating | Guernsey Electricity

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100% efficient hot water cylinders

Hot water cylinders

Cleaner, more efficient hot water cylinders powered by over 90% renewable energy. Enjoy a hot shower or relaxing bath using water heated by nature
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Hot water cylinders are a great choice for larger homes with greater demands for hot water. While combi boilers are able to heat water on demand in smaller properties, they cannot cope with several taps, showers and radiators being turned on simultaneously.

IMPORTANT: Please read this first

What is a hot water cylinder?

Electric hot water cylinders use electricity to directly heat elements inside the tank to heat water. These water tanks have their own power supply which automatically switches off when the water temperature you've selected on your thermostat gets reached.

This water can then be used for your hot water needs around the home. 

We recommend that they aren’t connected to your boiler and installed with a timer to take advantage of the low-rate Economy 12 electricity tariff. 

Top Tip

Save money and help the planet by heating your water at night
Between 11pm and 5am, the power station is not needed to top up our electricity demand. Set the timer on your thermostat to heat up at night for cleaner, greener hot water during the day

One size does not fit all.

Hot water cylinders come in different shapes and sizes to suit your home. 

Whether it's a small cupboard, a large attic, a garage or a utility room, there's a cylinder the right size and shape to meet your specific property needs. 90 litres or 250 litres, make sure you're getting the hot water you need with an electric hot water cylinder. 




Top Tip

Don’t wait for your boiler to break midwinter to make the change.
Spring and Summer are the best time to make the switch. As with a house extension or roof replacement, it takes time but is worthwhile.


Power Supply

It’s really important to plan ahead and check if your property needs a supply line cable upgrade. 

Electricity is delivered to your door through an underground network of cables. Some properties don’t have enough capacity in the existing service cable to supply a new heating system ad will need a service upgrade.  

Your installer can check with Guernsey Electricity by submitting an additional load application if your property needs a supply line cable upgrade

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Frequently asked questions

Making the switch to electric heating is a fantastic investment for your property. Like any property upgrade, the installation will take time to complete and we want to help answer your questions before you make the decision to change. 

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We recommend your electric hot water cylinder is installed with a timer to take advantage of your low-rate Economy 12 electricity tariff. Modern hot water cylinders are very well insulated and will normally keep your water warm during the periods your timer switches off the heating elements. 

If you heat up during your low-rate time bands, this will cost you over 50% less. And if you heat your water between 23:00 and 05:00, you will also be using 100% renewable electricity as the power station is not required as a top up during this off-peak period.

Using the immersion element in a water cylinder, the water is heated up in a similar way that a kettle boils water. The immersion element has a thermostat inside which only allows the immersion element to heat the water up to the desired temperature (usually 55°C). Once the cylinder temperature is achieved, the immersion element will switch itself off and on to maintain the desired temperature in the cylinder.

This will continue throughout the day unless a timer is fitted to control when the immersion element can be activated. This allows you to heat the cylinder water up solely in the Economy 12 low rate, therefore saving money on your electricity bill.

No - unless you are replacing an existing electric heating system. However, your preferred installer will always do their best to provide a solution in an emergency. 

Installation timeline

Switching to an electric system is a positive development for your property and similar to other property improvements such as extensions and roof renovations, it will take time to complete. 

Lead times will vary depending on workload and availability, and it is worth preparing for your switch to electric heating well in advance. Please be aware that your property may need a supply line cable upgrade which will add to the timeframe.   

Find out more 

We also recommend switching during the spring and summer months when possible so the work can be carried out when you do not need to use the heating. Depending on the work required, it may take several weeks from start to finish.  

We recommend checking current prices and tariffs online first.

Heating systems replace the volume of heat lost from your property, which means property insulation is the most effective way to reduce the running costs of any heating system. 

Electric Boilers and Underfloor Heating

These run on the Superheat Tariff. An electric boiler will cost the average customer in Guernsey roughly 30% less to run than a gas boiler. 

Oil is one of the cheapest commodities and although oil heating systems may initially have a lower running cost when new at around 91% efficiency, over time the cost to run your oil heating will increase as the efficiency decreases.  

Some customers have replaced oil boilers working at less than 70% efficiency, meaning over 30% of their bill was used to pay for waste greenhouse gas emissions rather than valuable heat for their home. 

Watch this explainer video

Air Source Heat Pumps

This is the least expensive way to heat a property. 

Unlike other heating systems, air source heat pumps provide three times as much energy as is put in. This means that for every £1 spent on electricity to run the heat pump, you could generate £3 worth of heat for your property. 

Electric heat pumps are much cheaper to run than traditional electric, gas or oil heating systems and run on the Heat Pump Tariff. 

Storage Heaters

These systems run overnight on a customer's off-peak Super Economy 12 Tariff and are the most cost-effective way to run a traditional electric heating system. 

If you’d like to make the switch to a electric heating but are unsure about the upfront cost, we can help spread the cost of your home heating affordably – just complete a short form and we’ll do the rest.  

Some customers have paid as little as £46 a month for their new electric heating system through our finance partner Cherry Godfrey Finance Limited.


A header tank is used to supply water to the central heating system. It will maintain the level of water needed as the water expands when heated. 

A new electric boiler needs a pressurised system and therefore won't need a header tank. If you have an existing gravity-fed hot water cylinder, this should be changed to a pressurised system at the same time as a boiler install. This will mean your header tank becomes redundant. 

There will be a different answer to this question for each property depending on:

  • the network infrastructure in your area
  • the supply line cable connecting your property to the network, and;
  • how much electricity other properties around you are using 

Your neighbour may be in a different position to you if, for example, they had electric heating installed a few years ago, or the network serving their property is from a different substation. 

Your installer will submit an Additional Load Form to Guernsey Electricity's new connections team to establish if there is enough power in the surrounding cable network to power an electric heating system in your property.   

If the supply line cable supplying your property has sufficient capacity, you will not need an upgrade. However to find this out, your installer will need to submit an 'additional load' application. 

If it is needed, often a supply line cable upgrade is either low cost or free of charge. 
The reason customers need to accept their heating installation quote first is to confirm with their installer that they still want to switch to electric heating based on the cost quoted, as it's common to request quotes from different installers for one job. This ensures only the chosen installer makes a single application to Guernsey Electricity for the additional electricity load required, rather than multiple applications for one job. This helps to make sure network capacity is available for other people who might need it.
If a supply line upgrade is required and it happens to involve a cost, the customer can accept or decline the supply line upgrade quote. If they do decline, then the installer cannot proceed with the installation of the electric heating and the customer is not liable for any costs.


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