Off peak electricity
The advantages of storage heaters
How storage heaters work
Using storage heaters in your home
Storage heater features to consider when buying
What size storage heaters to select
How to set your storage heater
Off peak electricity, often known as economy 7, is a supply that provides cheap rate electricity for 7 hours during the night. The cost of electricity on a economy 7 tariff is usually less than half the price compared to the normal domestic rate. To take advantage of economy 7 you need to ensure that you have an economy 7 meter installed. This measures your usage of power during the off peak period. Typically the 7 hour period is between 00.30 and 07.30 in the morning in winter and 01.30 and 08.30 in the summer. Although the daytime electricity and standing charges may be slightly higher, if you use economy 7, and schedule equipment like water heater, dish washer, washing machine and heaters to operate at night, you can still make significant savings overall.
The advantages of storage heaters
Storage heaters do tend to use slightly more electricity than conventional electric heaters giving instant heat, however, because the cost of the electricity used to charge them is at a rate less than half of the regular daytime rate, there is a significant overall electricity cost saving. The Domestic Heating by Electricity Good Practice Guide 345 estimates that an existing detached house would use £1436 on heating using the standard tariff and only £578 on a off peak tariff, with similar percentage savings being realised for smaller homes.
Compared to central heating systems, storage heaters are very easy to install with no requirement for plumbing, boilers, pipes or complicated control systems. Because the heaters have the characteristic of slow heat release throughout the day, they are ideal for use in homes that are occupied during the day.
Storage heaters are the ideal compliment to off peak electricity. The heater uses cheap night time electricity to 'charge up' with heat, which is then released during the day. Storage heaters basically comprise of dense blocks that envelope heating elements. The blocks and elements are closely insulated to minimise heat lose through the side of the unit. On top there is a control damper that can be set to allow the desired amount of heat out.
Using storage heaters in your home
Storage heaters are a useful addition to an existing heating system, and are often used in extensions, offices, workshops, hall ways and the like. For smaller homes storage heaters are a credible and cost effective alternative to a central heating system. The cost effectiveness of storage heaters does of course depend on being set up to receive off peak electricity tariff. Confirming that you can get a suitable supply and getting this set up should be the first stage before investing in storage heaters. Each heater needs to be wired independently to a separate consumer unit connected to the off-peak supply, and, as for all electrical installation work, the lEE Wiring Regulations must be observed.
Heating by storage appliances alone is normally not a practicable or cost effective aim and typically some provision should be made for some supplementary direct acting heating. Up to 90% of heating requirement provision by storage heaters is quite workable, and in very well insulated properties lower proportions are justified.
Storage Heaters perform better in well-insulated draught-proofed homes, where heat is lost from the building more slowly. So converting to heating by storage heaters should be complimented by consideration of the house's insulation. Once set up on Economy 7, or a similar off peak tariff, then to make the most of the available rate also consider heating your water with Economy 7 and running your other power heavy equipment on it using timers, e.g., washing machine and dish washer.
Storage heater features to consider when buying
In addition to storage capacity, the principal feature is effective controls and insulation which together determine the output rate of the stored heat. As storage heating is less responsive to changes in demand, features that allow the emission rate to be altered readily are desirable, and indeed make the system more efficient. The amount of storage needed to meet daily heating requirements should be considered carefully at the design stage; the table in the section below (What size storage heaters to select) provides some guidance.
Storage heaters are manufactured in a range of sizes with heat storage capacity quoted in kWh, and a typical large size heater is capable of being charged at a rate of 3.4kW and able to accept a maximum charge of 23.8 kWh in a 7 hour charging period. Automatic charging systems are preferable because they offer the facility for automatically controlling the amount of input charge considering the room's temperature and the existing amount of heat in the blocks (heat storage media).
| Feature | Explanation |
| Input rating | The input rating in kw is the power used when on its charging cycle, i.e. at night. |
| 7 hour charge (sometimes referred to as the acceptance charge) | The seven hour charge value is roughly the kw rating multiplied by the 7 hour charging period i.e. for a 2.55 kw storage heater the 7 hour charge value would be 17.85 kwh. Typically model numbers use the rounded up kwh figure as their basis, e.g. SH18. |
| Dimensions | The dimensions of the unit should be considered as it has to be located against exiting walls. It may be the case that space restraints mean that rather than one large heater you need to use 2 smaller heaters. Storage heaters are significantly deeper than conventional radiators so take care to consider the depth of the unit. A couple of cm too deep could make the difference between a useful heater and an obstacle in the room. Our listed heaters from Elnur use the best thermal materials for heat storage and insulation which makes them offer equivalent performance to competing brands, but with the aesthetic benefit of a thinner profile. Typically Elnur units are not as wide as their equivalent models from other manufacturers. Also consider the height of the support legs, and how the unit will be installed bearing in mind skirting boards etc. |
| Manual or automatic | Manual ones are cheaper than automatic ones, however it is generally accepted that ones with automatic input control, consume around 15% less electricity, so the investment in an automatic will pay for itself in a relatively short time. |
| Outlet regulator | Always ensure that your prospective heater has a outlet regulator. It provides a smoother discharge heat than one without. All our storage heaters have this feature. |
| Combination heating | Combination units have a convector heater incorporated into the unit as well as the standard storage heater system. It means that the storage heater is typically used to provide the bulk of the heat (say to 18°C), however, a instant top up on heat out put can be achieved using the convector. The addition of the convector also means that you have an alternative heat source for those odd occasions when it is needed to provide all the heat, e.g. when you come back from holiday having had the heater switched off, or when you are up beyond the time when the stored heat has been discharged. These units are ideal for rooms that have higher occupancy, like living rooms. |
| Fan Storage Heaters
|
Fan storage heaters are a higher level of sophistication to using low tariff electricity. Instead of automatically emitting the stored heat by convection throughout the rest of the day, the fan assisted storage heaters incorporate a low speed silent fan, which draws air through the core of the heater and discharges through the vent at the base of the heater at a time that suits you. Until then the heat is stored efficiently inside the high thermally insulated unit. The insulation used on the fan assisted units has more than double the normal thickness of the standard storage heaters. This makes the fan assisted storage heaters one of the most efficient in our range at storing heat. Ideal for home or office use, the fan assisted storage heaters work from an off peak tariff supply. The low speed fan is quiet in operation and requires a 24hr supply. The fan is controlled via a separate room thermostat control, which is supplied with the unit. The unit can also be operated via any suitable thermostat or timer controlled thermostat. |
| IP rating | Our listed static storage heaters are all rated to IP22, which means that they are sufficiently safely insulated to use in 'Zone 3' of bathrooms. If you are planning to use one in a bathroom, check the rating. |
What size storage heaters to select
The tables below are intended as a rough guide to selecting a heater with the appropriate input rating. Although our heaters have input ratings up to 3.4kw, the table includes selections up to 8.5kw. The internal construction of the heaters is modular and the an increase in model size is reflected internally by an additional 4 heat storage blocks increasing the input rating by 0.85kw. The kw ratings in the tables are all divisible by 0.85kw, so that the larger ones can be achieved by a combination of storage heaters rather than only one.
If you require just a background level of heat for your home or room and plan to use other heaters to 'top up' as required, then use the top table. If however you plan to use the storage heater as the only room heat source and you require a comfortable temperature then use the bottom table.
Both tables have been based on the assumptions of ceiling heights of 2.4m, no cavity wall insulation, average external temperature of -2°C and roof insulation of 100mm.
| Kw rating to for background heat (18°C) | Floor area (m2) | ||||||||||
| 3 | 6 | 9 | 12 | 15 | 18 | 21 | 24 | 27 | 30 | ||
| outside wall length (m) | 1.5 | 1.7 | 1.7 | 1.7 | 1.7 | 2.55 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 |
| 2 | 1.7 | 1.7 | 1.7 | 1.7 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | |
| 3 | 1.7 | 1.7 | 1.7 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 3.4 | 4.25 | |
| 4 | 1.7 | 1.7 | 2.55 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | |
| 5 | 1.7 | 1.7 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | |
| 6 | 1.7 | 2.55 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | |
| 7 | 2.55 | 2.55 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | 4.25 | 5.1 | ||
| 8 | 2.55 | 2.55 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | 4.25 | 5.1 | ||
| 9 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | 4.25 | 5.1 | 5.1 | |||
| 10 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | 5.1 | 5.1 | 5.1 | |||
| 11 | 3.4 | 4.25 | 4.25 | 4.25 | 5.1 | 5.1 | 5.1 | ||||
| 12 | 4.25 | 4.25 | 5.1 | 5.1 | 5.1 | 5.1 | 5.95 | ||||
| 13 | 5.1 | 5.1 | 5.1 | 5.1 | 5.95 | 5.95 | |||||
| 14 | 5.1 | 5.1 | 5.1 | 5.95 | 5.95 | ||||||
| 15 | 5.1 | 5.95 | 5.95 | 5.95 | |||||||
| 16 | 5.95 | 5.95 | 5.95 | 6.8 | |||||||
| 17 | 5.95 | 5.95 | 6.8 | ||||||||
| 18 | 6.8 | 6.8 | |||||||||
| 19 | 6.8 | ||||||||||
| 20 | 6.8 | ||||||||||
| kw rating achievable with multiple units | |
| kw rating achievable with single units or multiple units |
| Kw rating to for comfort heat (21°C) | Floor area (m2) | ||||||||||
| 3 | 6 | 9 | 12 | 15 | 18 | 21 | 24 | 27 | 30 | ||
| outside wall length (m) | 1.5 | 1.7 | 1.7 | 1.7 | 2.55 | 2.55 | 2.55 | 3.4 | 3.4 | 4.25 | 4.25 |
| 2 | 1.7 | 1.7 | 1.7 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | |
| 3 | 1.7 | 1.7 | 2.55 | 2.55 | 2.55 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | |
| 4 | 1.7 | 1.7 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | 5.1 | |
| 5 | 1.7 | 2.55 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | 5.1 | |
| 6 | 2.55 | 2.55 | 2.55 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | 5.1 | 5.1 | |
| 7 | 2.55 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | 5.1 | 5.1 | 5.1 | ||
| 8 | 3.4 | 3.4 | 3.4 | 4.25 | 4.25 | 4.25 | 5.1 | 5.1 | 5.95 | ||
| 9 | 3.4 | 4.25 | 4.25 | 4.25 | 5.1 | 5.1 | 5.1 | 5.95 | |||
| 10 | 3.4 | 4.25 | 4.25 | 5.1 | 5.1 | 5.1 | 5.95 | 5.95 | |||
| 11 | 4.25 | 4.25 | 5.1 | 5.1 | 5.95 | 5.95 | 5.95 | ||||
| 12 | 4.25 | 5.1 | 5.1 | 5.1 | 5.95 | 5.95 | 6.8 | ||||
| 13 | 5.1 | 5.1 | 5.95 | 5.95 | 5.95 | 6.8 | |||||
| 14 | 5.95 | 5.95 | 5.95 | 6.8 | 6.8 | ||||||
| 15 | 5.95 | 6.8 | 6.8 | 6.8 | |||||||
| 16 | 5.95 | 6.8 | 6.8 | 8.5 | |||||||
| 17 | 6.8 | 6.8 | 8.5 | ||||||||
| 18 | 8.5 | 8.5 | |||||||||
| 19 | 8.5 | ||||||||||
| 20 | 8.5 | ||||||||||
| kw rating achievable with multiple units | |
| kw rating achievable with single units or multiple units |
How to set your storage heater
It is a good idea to set overnight charging correctly otherwise you may find there is insufficient storage for the next day's requirements, in which case more heat will be required from plug in heaters at the more expensive on-peak rate, or an excessive amount that will be wasted if mild weather reduces the need for heating.
Basically all storage heaters have at least two setting dials. One is for setting the input requirement (i.e. the amount of charge that will go into the heater overnight), and the second dial is for controlling the heat output during the day and evening. The secret is getting into the habit of monitoring the weather forecast, so that for instance, if it is forecast to drop in temperature the following day, increase the input setting, so that the unit will gain enough heat charge to release the next day. Conversely, if the temperature is forecast to rise decease the heat input. The output dial should be altered to suit your homes' occupancy. For instance, homes that are occupied only towards the end of the day, the output would be closed down, to save more heat for later, when the output can be opened up to release more heat. It is important in this case to remember to close down the output control last thing at night so that the next day the heat is not mostly lost during the day.
Setting storage heaters is a skill that develops over time as you get more familiar with the characteristics of your heaters but generally most people start with the input setting in the mid range and adjust up or down as their experience dictates. Well insulated homes are not nearly so affected by external temperature swings and once a optimum setting has been found, it should only require changing to reflect changing season and on the odd time when very cold periods are forecast. Storage heaters in less well insulated homes will require the input setting adjusting more often.