Storage Heater Size: Room-Specific Solutions

When choosing a storage heater, it's important to select the right size for your room. The wattage you need will depend on factors such as room size, insulation quality, and property location. Various online calculators can help determine the required wattage, taking into account ceiling height, external temperature, and insulation type. It's recommended to opt for a higher wattage if calculations fall on the borderline between two sizes, as larger heaters can be adjusted to reduce heat output if needed. Multiple heaters can be used in a room if required wattage exceeds the capacity of a single heater.

Calculating the right storage heater size

The right storage heater size depends on the size of the room you want to heat, the quality of its insulation, and the location of your property. Here is a step-by-step guide to calculating the right storage heater size:

Step 1: Measure the dimensions of your room

First, measure the length, width, and height of the room in metres to calculate the total space (volume) to be heated. For example, if you have a room with a 3-metre-long wall, a 5-metre-wide wall, and a standard 2.4-metre-high ceiling, the volume of the room is 36 cubic metres (3m x 5m x 2.4m = 36m³).

Step 2: Determine the wattage required

Once you know the volume of your room, you can use an online storage heater calculator to estimate the wattage required to heat that space. These calculators will typically ask for the volume of your room and may also take into account factors such as ceiling height, insulation type, and average external temperature.

Step 3: Select a storage heater with the appropriate wattage

After determining the required wattage, you can select a storage heater or a combination of storage heaters that adds up to the total wattage needed. For instance, if your room requires 5 kilowatts (kW), you could use a 1.7 kW and a 3.4 kW storage heater together.

Step 4: Consider the available space

It's important to think about the available space in the room when choosing heaters. A single 3.4 kW storage heater might adequately heat the room, but two 1.7 kW heaters could be a better option if they make better use of the space.

Step 5: Measure wall space and check product dimensions

Before purchasing, ensure you've accurately measured the wall space where you plan to install the heater(s) and checked the dimensions of your chosen product(s) to ensure they will fit.

Step 6: Consider the depth of the storage heaters

Don't forget to check the depth of the storage heaters, especially if you're installing them in a walkway or near a door. Storage heaters are typically bulkier than conventional central heating radiators, usually measuring between 15 and 20 centimetres deep.

It's important to note that online calculators and guides provide estimates, and for more complicated calculations or specific requirements, it's recommended to consult a qualified electrician or seek expert advice.

Wattage requirements

The wattage requirements of a storage heater for a room depend on several factors. The industry standard is 10 watts per square foot, which is typically used for newer homes with basic electric baseboard heating. For homes constructed with thermal insulation or ICF, 7 watts per square foot is sufficient, assuming the latest windows and insulation.

Thermal storage heating, on the other hand, requires 12 watts per square foot. This higher wattage ensures the heater is oversized and has a longer storage time. For instance, a 100-square-foot room would need a 1200-watt heater (100 square feet x 12 watts).

It's worth noting that 1000 watts equal one kilowatt. So, for a room requiring 5 kilowatts, you could use a combination of heaters, such as a 1.7-kilowatt and a 3.4-kilowatt storage heater, to meet the total wattage requirement.

When determining the wattage, it's important to consider the size of the room, the quality of insulation, and the property's location. Additionally, the height of the ceiling, the presence of cavity wall insulation, external temperature, and roof insulation can also impact the required wattage.

Online calculators and sizing charts can assist in determining the appropriate wattage for your specific room and requirements.

Insulation considerations

The wattage you need to heat a room depends on the size of the room, the quality of its insulation, and the location of your property. The better the insulation, the less wattage you will need to heat the room.

Insulation provides resistance to heat flow and lowers your heating and cooling costs. It slows down conductive heat flow and convective heat flow. Conductive heat flow is how heat moves through materials, for example, when a spoon placed in a hot cup of coffee conducts heat through its handle to your hand. Convective heat flow is how heat circulates through liquids and gases, and is why lighter, warmer air rises, and cooler, denser air sinks in your home.

The effectiveness of an insulation material’s resistance to heat flow depends on how and where the insulation is installed. For example, insulation that is compressed will not provide its full rated R-value. R-value is the thermal resistance of an insulating material, and the higher the R-value, the greater the insulating effectiveness. The R-value depends on the type of insulation, its thickness, and its density.

When choosing insulation, you should consider indoor air quality impacts, life cycle costs, recycled content, embodied carbon, and ease of installation.

Room dimensions

The size of the storage heater you need depends on the size of the room and the quality of its insulation. The larger the room, the larger the heater needs to be. Better insulation leads to less heat loss and less energy required from the heater.

To calculate the correct heater size, you need to know the length, width, and height of the room, along with the insulation factor of the room. The insulation factor is influenced by the age of the building, the materials used in the walls and roof, the presence and condition of insulation materials, the type and condition of windows, and how airtight the room is.

For example, let's say you have a room with a length of 10 feet, a width of 15 feet, and a height of 8 feet. If the room has poor insulation, the insulation factor would be 7.5. Using the formula HS = L x W x H x IF, where HS is the heater size in BTUs, L is the length, W is the width, H is the height, and IF is the insulation factor, we can calculate the required heater size. In this case, the heater size would be 15,000 BTUs.

It's important to note that different types of heaters, such as radiant heaters, convection heaters, or forced-air heaters, may have varying efficiencies in certain environments. For instance, radiant heaters are better at directly heating objects and people in a room and might be more effective in poorly insulated spaces.

Additionally, the orientation and location of the room can impact its heating requirements. Rooms facing south in the northern hemisphere tend to receive more direct sunlight, reducing heating needs during the day. Rooms in colder climates or exposed to strong winds may need a larger heater to maintain a comfortable temperature.

Electricity tariffs

The wattage you need to heat a room depends on the size of the room, the quality of its insulation, and the location of your property. To work out the required wattage for each room, you can use a storage heater calculator. The wattage measures the maximum power output of your storage heaters.

To enjoy the money-saving benefits of storage heaters, you will need to be on a night-time electricity tariff such as Economy 7. The Economy 7 tariff charges lower rates for electricity used overnight, typically between midnight and 7 am. The time period for the reduced rate varies from region to region and may change depending on the time of year, so it is important to check the details of your tariff.

There are many different types of tariffs, ranging from 2 to 10 pages in length. It is important to understand how these tariffs work to know what you are being charged for your electricity and if there are opportunities for savings or refunds. Tariffs can have large variations in the actual price per kilowatt-hour, and there are countless variables that go into the actual price of your electricity.

It is important to note that changing your tariff can have consequences. In some cases, you may not be able to change it back for 12 months, which could result in large additional costs.

Frequently asked questions