Radiator experts are frequently asked whether electric radiators are “efficient” and, more specifically, whether storage heaters are more “efficient” than other types of electric heating.
When it comes to radiators, the word “efficiency” can be interpreted in many ways. From our experience, when a customer asks “Which radiators are the most efficient?” they could mean:
- Which radiator gives out the most heat for its size?
- Which radiator is the cheapest to run?
- Which radiator uses the least fuel?
- Which radiator heats up the quickest?
- Which radiator is most environmentally friendly?
Electric radiators are generally regarded as being 100% efficient as almost 100% of the electricity consumed by the radiator is converted into heat and released into the room. (This differs from piped hot water central heating systems where some of the heat can be lost through the pipes on route to the radiators and the boiler.) Therefore it could be argued that all electric radiators are equal in efficiency as the energy put into the radiator will equal the amount of heat put out.
So the questions above cannot be answered by looking at efficiency; instead the key to choosing the best electric radiator is to decide which would be most effective in your specific situation.
This article aims to give clear information and facts to help you choose the electric heating product that best matches your unique lifestyle and heating needs. This will then enable you to minimise any wasted energy, which in turn will help reduce the amount of fuel you use, therefore reducing the cost of your electricity bills and your impact on the environment.
Whichever form of electric heating you opt for, we always suggest looking at the various energy providers’ tariffs to compare pricing as the cost of electricity can vary significantly; pricing does not only vary between suppliers but also between the wide varieties of tariffs offered by each supplier.
Below we have provided a summary of the electric heating options available on the market detailing their pros and cons to help you choose which option is the best for your home.
Electric heaters or electric radiators generally come in two distinct styles:
- Storage heaters; or
- On demand heaters, namely;
- Radiant heating panels;
- Convectors; and
- Liquid-filled electric radiators.
These make use of the cheaper electricity that is available at night on an economy tariff. Electricity is used to heat up ceramic bricks within the heater overnight which then “store” the heat and slowly release it gradually over the course of the following day. Storage heaters were historically seen as the only real alternative to gas central heating and are still a common sight in homes across the UK.
Example: Using a storage heater in a room that requires 1kW of heat
- Require a storage heater that consumes around 3.2 kiloWatts or kW per hour.
- Economy 7 tariff = 7 hours electricity at a cheaper rate during the night.
- Storage heater is set to “charge” for these 7 hours, consuming 3.2kW per hour for 7 hours.
- Consumes a total of 22.4kW per night.
- Releases the 22.4kW of heat consumed over a 24 hour period = heat output of 0.933kW of heat per hour.
This means that storage heaters are efficient, insomuch as they give out all the energy that they consume, however they do consume a lot of energy. Interestingly, storage heaters were originally developed during the strikes of the late seventies and there is an argument that the government encouraged their use at this time as they were keen to keep the power stations running to make the country dependent on the coal industry.
Storage heaters can offer a practical solution for many homeowners; for example, as the heat is released throughout the day, storage heaters are more suitable for people who are retired or at home throughout the day. Alternatively, if you work full time and do not require heating during the day, storage heaters may not be the best option as heat will be emitted even when you are not there, resulting in unnecessary energy wastage.
The nature of storage heaters does make them harder to control than “on demand” heating products. For instance, consider the following scenarios:
- You spontaneously decide to go out for the day, but you have already paid for that day’s heating;
- You go on holiday and turn the heating off, but there will be no “charge” in the heater when you return, meaning time sat in a cold house; and
- You may want to turn the heating off in summer, but an unexpected cold snap might mean you need to do an urgent “boost” on the heaters during the day, which would be charged at a high peak rate.
- This lack of controllability makes homeowners reluctant to deviate from the pre-determined charging hours and standard usage.
Also as storage heaters age, their internal insulation can break down; resulting in heat being expended too fast and so supplementary heating may be required for later on in the day; this supplementary heating would be charged at the peak rate per hour, rather than the economy rate. Bear in mind that the peak rates on Economy tariffs are usually significantly higher than at any time on non-Economy tariffs and these rates apply to all appliances used during peak hours, not just radiators.
Storage heaters are often deemed unattractive and the nature of their design makes them quite bulky protruding significantly into a room.
On demand heaters
The following 3 forms of electric heating consume electricity “on demand” unlike storage heaters. “On demand” heating products allow you to only turn the heater on when you need heat, and turn it off when you don’t need heat. This makes them the better option for avoiding wasted energy as you only have the radiators on as and when needed and there is no need to second guess what the weather will be doing 24 hours in advance, which is particularly useful with the unpredictable British climate. On demand heaters are normally used with regular, non-Economy electricity tariffs, which do not use cheaper night-time rates.
Example: Using an on-demand heater in a room that requires 1kW of heat
- Require an on-demand heater that consumes 1 kW per hour.
- Standard electricity tariff = same rate at all times of the day.
- For someone who works 9am to 5pm; On-demand heater timer is set to come on at 7am till 8am and 6pm till 11pm, so consumes 1kW per hour for 6 hours.
- Consumes a total of 6kW per day giving a heat output of 1kW of heat per hour.
This example shows a significant reduction in the amount of energy used by someone who works standard hours; when comparing a storage heater with an on demand heater, despite the electricity being charged at a higher rate than on the rates for the Economy 7 tariff, this could still be the most cost effective option in this type of scenario.
On demand heating products, as detailed below, usually provide a better solution than storage heaters to the question “which radiator is most efficient?”
- Radiant heating panels are either hollow, or, more commonly, are a sealed unit. An electric element is concealed within the radiator, which heats up and radiates heat out evenly from the front of the radiator. Radiant heat is absorbed by the furniture, fabrics and carpet in a room, so the warmth is retained for longer. This type of radiator is particularly good for people with dust allergies as their flat panel makes them easy to clean and they don’t “convect” heat or promote air circulation to heat a space; these factors help to reduce the amount of dust being circulated around a room.
- Convectors, or heaters that make use of convection, warm a room by following the principle that hot air rises. Electric convectors usually consist of a hollow case; open at the top and bottom with a visible coil heating element. (Quite often, when these radiators are switched on and you look inside them, you can see the heating element glowing red inside the radiator.) Convection heating works by creating a cycle of air circulation; cool air comes from underneath the radiator, it is drawn up from the bottom of the radiator and then warms up and rises or “convects” as it passes the heating element, emitting warm air from the top of the radiator. This warm air rises to the ceiling, cools and falls back to the floor then repeats the process. Electric fan heaters also work on the same principle; the only key difference being that the fan forces air across the electric element speeding up the movement of warm air. This means that fan heaters will blast warm air into a room very quickly, but as soon as they are turned off, the room will cool almost immediately. Radiators that work on convection can sometimes be the cause of black marks seen on walls above radiators; these are caused by the residue of dust being drawn up into the radiator and burnt onto the open element.
- Liquid-filled electric radiators operate in similar way to radiant panel type heaters; they are sealed units with an internal heating element that releases this heat via the outer case, however the elements are submerged in a liquid such as oil, water with corrosion inhibitor or heat transfer agent/gel rather than being dry. Depending on the design of the radiator, the heat generated can be entirely radiant or a combination of radiant and convected heat. Historically, oil was used to fill electric radiators. However water is now increasingly common as this offers a cleaner option; for instance, The National Trust uses water-filled electric radiators as they do not want to risk using oil which could cause damage to a historical property or its contents.
So in summary, a radiator is just a vessel designed to release energy in the form of heat and the amount of heat that a radiator releases will depend on the amount of energy put into it; this is particularly true of electric radiators, where they will perform at approximately 100% efficiency.
- Storage heaters use a large amount of cheap electricity, but lack controllability resulting in energy wastage. “On demand” heaters use less electricity and offer greater flexibility, but this electricity is not available on an Economy tariff.
- Convected heat immediately warms the air in a room, but the heat dissipates almost immediately as the heat source is turned off. Radiated heat takes longer to warm a room as it heats objects not just the air, but this means that the room stays warm for much longer.
In practice, there are many aspects that will determine the best radiator(s) for your project including your lifestyle e.g. working hours, size restrictions, interior décor, budget and availability; your choice will be governed by which factors take priority. The research proves that when it comes to heating, there is no magic “one-size fits all” solution.
For more advice on choosing the most effective electric heating product, speak to an electric radiator specialist.
Source by Helena Gerwitz