Economy 7 or Economy 10 Heatwise Tariff?

Many households who are stuck with Electricity as their only form of heating, are tempted by the lure of Economy 10 heatwise heating, as an alternative to older Economy 7 heating. The Economy 10 tariff is also widely known as the Heatwise Tariff.

The main differences between Economy 7 and Economy 10 heatwise heating are the number of hours and the periods where the Electricity is sold at a reduced ‘off peak’ rate. For example Economy 7 Heating will offer one 7 hour period of cheap overnight Electricity, normally between the hours of Midnight and 7AM, whilst in comparison, Heatwise economy 10 will offer a total of  ten hours of cheaper rate Electricity, spread over three periods throughout the night and daytime. Here is an example of Economy 10 / Heatwise periods

  • 3 hours in the afternoon
  • 2 hours in the evening
  • 5 hours over night

Typical Heatwise tariff times:- Afternoon:- 1pm – 4pm, Evening 8pm – 10pm, Overnight 1am-6am

Economy 10 / Heatwise heating is normally only suitable for those households which have ‘wet’ electric central heating, and this normally produced by an Electric Boiler which acts like a big immersion heater, warming the water in the boiler during the Economy 10 heatwise periods, which is then stored in a central heat store and then circulated to radiators throughout the house, in a similar way to Gas central heating.

Economy 10 heating is largely unsuitable for older  storage heaters, as these types of heaters normally require a full single seven hour period in which to store enough heat for later use, and the multiple shorter 2 – 5 hour periods provided by Economy 10 / heatwise simply do not  maximise enough storage capacity of the heaters, resulting in them not warming adequately enough to store enough heat to adequately warm a house between their ‘on’ periods

Economy 10 heatwise users also tend to pay a higher Electricity rate than Economy 7 users, and whilst the Electricity sold on the Economy 10 heatwise tariff is still cheaper than a standard electricity tariff, it still falls far short of the cost of Economy 7.

To quote one of Eon’s own representatives:- You’re right; Heatwise is more about comfort than economy.

(Quote Source:- Eon Representative on Money Saving Expert Forum)

Enough said!

In addition, Economy 10 users have a very limited choice of Electricity supplier, and currently only two energy suppliers in the UK provide the Economy 10 tariff and these are Eon and EDF, this ultimately means that there is less competition, and less opportunity for Economy 10 users to haggle and to shop around. You will also be unlikely to find heatwise available on Comparison sites, and the lack of information in respect of the Economy 10 heatwise tariff on both EDF and Eon Energy websites is highly suspicious and lack of visible public information on these tariffs are possibly the biggest mystery known to the energy market, in fact its virtually impossible to get Economy 10 / Heatwise tariff prices from either company website!.

The best recommendation to any tariff or company is indeed word of mouth, however looking around the many internet forums, it does seem that many existing heatwise economy 10 customers are less than happy with either their chosen form of heating or indeed their heatwise tariff, with many reporting very high Electricity bills, and the inability to change to a better tariff (because one simply does not exist).

The reason behind why Electricity bills on the Heatwise tariff, is probably down to the fact that just like Economy 7 tariffs, the cost of the Electricty sold during the ‘peak’ rate periods is much higher than other households pay on a standard single tariff ( in order to claw back some of the saving it makes on selling the cheaper rate electricity). Because there is also some reliance on the electric boiler at some point using peak rate electricity, such as during colder days, when the heat store is unable to provide the demand, then inevitably those househouds begin to pay well over the odds for the Electricity to do it, should the boiler need to run outside of the cheaper rate periods (and during mid winter this would be a common occurance).

4 Responses to Economy 7 or Economy 10 Heatwise Tariff?

  1. Trevor Beamond says:

    Economy 10 heating is largely unsuitable for older storage heaters, as these types of heaters normally require a full single seven hour period in which to store enough heat for later use, and the multiple shorter 2 – 5 hour periods provided by Economy 10 / heatwise simply do not maximise enough storage capacity of the heaters, resulting in them not warming adequately enough to store enough heat to adequately warm a house between their ‘on’ periods.

    This seems to me to be rubbish, the more often the heater is recharged, the nearer it can keep its temperature to a high level

  2. admin says:

    Economy 10 is now generally the Tariff of choice for Electric Boilers, where the heat store is a well insulated cyclinder holding up to 300 litres of water, pumped around radiators in several different rooms. If you were to switch on an average 10 – 15 year old Storage Heater from cold, and a standard 3kw immersion heater from cold both at the same time, you would find that after one hour the case of the Storage Heater would still barely be warm, and the heat given off it to be minimal, but the water in the immersion heater would be getting close to its set thermostat value and probably be more than hot enough to wash in.

    My example shows that is is much quicker for a tank of of water to heat, compared to the bricks used in a Storage Heater, so the Water based ‘Wet’ Electric Central Heating System requires less initial operating time to heat its heatstore up from cold, compared to the time needed for a Storage heater to heat its bricks, so the faster heat up period of the Wet System makes them far more suited to the shorter overnight period offered by E10. In contrast, a pumped ‘Wet’ System circulating around a house with multiple radiators will lose heat far more faster than the trickle convection from an individual storage heater, hence why the Wet Heating system requires two further off peak top ups during the day, whilst a correctly sized Storage Heater system shouldn’t need any further top ups until the Off Peak period begins again, once it has had a 7 hour overnight “charge”. In larger rooms, Storage Heaters are often fitted in multiples, in order to ensure that there is enough heat to keep the room warm for the occupancy period between the off peak ‘charges’ of heat, on the older, original systems this has been calculated based on the original E7 tariff, so running them on an E10 tariff with a shorter initial overnight charge, may result in the room being cold first thing in the Morning.

    Using my own Living Room as an example, which is heated by a 3.4kw and a 2.45kw Storage Heater, if set on their maximum settings, and run for seven hours on E7 the 3.4kw heater will charge with 23.4kw of heat (7 x 3.4kwh) and the 2.45 heater will charge with 17.15 kw worth of heat (7x 2.45kwh), together that is 40.55kw worth of stored heat, ready to be convected throughout the day at a rate determined by the “output” setting on each heater. Assuming an average sized room requires between 2kw – 3kw worth of heat in order to keep it at a constant temperature, that 40.55kw of stored heat from the two heaters should be enough to heat that room for between 13.5 – 20 hours.

    I stopped using Storage Heaters because they didn’t work well for me, largely because my house dates back to the early 1900’s and as an insulation level to match, which meant that a room required far more than 3kw per hour to heat it, and I found a much cheaper method of ‘on demand’ heating to simply heat the room for the periods when I was actually in it, plus working shifts also meant that for large chunks of the day, I was heating the house needlessly whilst it was unoccupied, however for anybody in and out of the room at various times of the day in a reasonably modern property, with double glazing and loft insulation that initial 40.55kw of heat gained from a 7 hour overnight charge should be more than enough to keep an average sized room warm for over 12 hours, and there really shouldn’t be the need to pay more for the additional off peak top up’s during the day, on the more expensive E10 tariff.

    A lot of the disappointments from Economy 7, comes from systems simply not being used or set up correctly, and the balance between the Heat Input and Heat Output controls not set up, to match the lifestyle of the people living in the building. Often ‘Input’ Thermostats on Storage Heaters, are set with Economy in mind, rather than practicality so the Heater(s) run out of heat sooner than required, however as the calcuation above shows, there is no reason why a correctly set up and sized system should fail to heat a room properly on the original E7 tariff.

    You are also assuming that Standard Storage Heaters will continually heat up whenever Electricity is supplied to them. Storage Heaters have Thermostats in them, a small bi-metallic strip which if working correctly will switch off the current to the Elements once the bricks reach a pre-set temperature – the level of which is determined by the setting on the Thermostat. In a Storage Heater in good condition with the Output “Damper” set correctly the heat loss between the Overnight period ending, and the first ‘top up’ period around lunchtime should be minimal, making the first 2 hour period of daytime E10 off peak Electricity, largely superfluous.

    You also have to factor in the cost difference between the two, Economy 10 off peak charges are higher than Economy 7 Off Peak periods, currently costing an average of 8.7p per Kw/h for E10 Off Peak, compared to 5.5p per Kw/h on Economy 7. Therefore taking into consideration a 3.4kw storage heater on its full setting would cost a maximum of £1.31 for a 7 hour charge on E7, compared to a maximum of £1.48 for a 5 Hour Charge on Economy 10 you would effectively be paying more money for what is actually a shorter duration of overnight heat storage, and if you did find that with the reduced 5 hour overnight period, the room wasn’t warm enough in the Mornings, then you would probably have to supplement it by using a portable Electric heater, running on expensive peak time Electricity, which would quickly negate any savings offered on the two further E10 periods later in the day.

    The only time you would get the full advantage of an E10 Tariff would be if you had the newer type of Storage Heaters with panel heaters built in, such as the Duo-Heat system, where you can have the panel or fan heater section of the heater running continuously to boost the heat throughout the additional 2x 2 hour off peak periods, there are also modern versions of Storage heaters designed for E10 use, which again are designed around the E10 tariff, however the article assumes conventional storage heaters are in use, and running these on E10, instead of E7 will probably prove to be false economy.

  3. Abbey says:

    I have recently moved into a flat with a electromate 2000 boiler with wet radiators, the flat has two very large rooms and an empty very cold property below, dont think the concrete floors are insulated either, can feel the cold rising. the boiler is 10 to 15 years old and is running on economy ten. It is set to come on between 20.00 and 22.00 and one hour in the morning…the flat is freezing and the bills are astronomical. How can I heat the flat economically?

  4. admin says:

    If you live alone or as a couple then you may be better off just heating the room that you are using as you use them rather than heating up an entire water store and then heating the entire flat, I recommend either using an Oil Filled Radiator, or Convector Heater. The only negative to doing this, depends on whether you need to use the Electric Boiler to heat the bathroom, or whether there is a wall mounted heater fitted that you could use, as and when required?. This will probably save you some money over using the Electric Boiler, but unfortunately there is no really cheap option for Electric Heating as its still one of the most expensive methods of heating a flat / house, even on E10 / E7 tariffs, especially if you need heat outside of the cheaper off peak periods.

    For cheaper, alternative room heating, you may want to read the page on using a modern paraffin inverter heater, don’t worry technology has moved on a lot since the days of smelly, messy paraffin heaters from decades ago, I used two of these myself when living in an Economy 7 heated flat, and still use them now in the rooms that don’t have radiators. Back in the days when I used them in the All Electric Flat, I reduced my heating bills from around £100 a month to £40 – £50 a month, so they pay for themselves quite quickly. These heaters are portable and you use them just like any other portable heater as they need no flue or installation, they also run off cheap paraffin (or domestic heating oil) which costs a fraction of the equiv cost for the same amount of heat from an Electric Boiler, especially outside of the cheaper periods.

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