Early models were insulated by the use of asbestos lining to the casing; manually moving a lever caused a metal plate, also asbestos lined, to press up against the bricks to contain the generated heat. Towards the end of day, as temperatures dropped, the lever could then be released and thus the heat was regulated to a reasonable degree.
When asbestos was banned for use in the home, Economy 7 radiator manufacturers were already changing over to electronic damping controlled by the output dial. The dial operates a bi-metallic strip which pushes a rather lightweight plate against the bricks, the result is that more heat escapes both during the 7 hour charging and the earlier hours of the day.
The vast majority of Economy 7 users therefore don’t re-set the output dial to minimum before retiring and then gradually open it during the day as they generally find it makes little noticeable difference to what is a time consuming exercise.
Today many Economy 7 radiators, although branded with well-known manufacturers names, are actually imported from the Far East. Although they look rather more attractive than older models many complain they perform less well than the replaced units. This is partly because an effective heat controlling material alternative to asbestos, has not been found.
There are several other reasons as to why this is the case including poor insulation, lighter bricks which are unable to hold as much heat and which fissure more quickly and generally poorer quality materials.
Heating elements do tend to break quickly and are sometimes difficult to replace. Overall the Economy 7 market is considered to be mature, with the only significant market left being the replacement sector, increasingly unpopular due to the difficulty of control and a very uneven heat output over the 24-hour cycle.
Social housing landlords report Economy 7 heating generates more complaints from their tenants than any other single issue. In postcodes with restricted or no mains gas, Economy7 daytime tariffs are around 35% to 50% more than none Economy 7 tariffs, which is an area of some annoyance and frustration to rural and semi rural consumers.
Today modern power stations are far more able to control electricity production levels than previously where it took up to 72 hours to start up or stop production, therefore political and/or economic pressure to keep Economy 7 has been mitigated.
This hasn’t stopped manufacturers attempting to make Economy 7 more attractive; one solution sees a daytime tariff panel heater fitted inside the Economy 7 radiator casing to provide for warmth from the late afternoon/early evening until 12 midnight. However this solution still doesn’t get away from the inherent problem of controlling the Economy 7 part of the unit, nor does it help when the daytime tariff could mean the 2kWh heating plate inside a 3.4kWh E7 rad would cost up to 30p per hour on many Economy 7 tariffs.
Whilst there are no plans in the UK to move away from Economy 7 both Germany and Sweden have recently implemented partial bans on the fitting of Economy 7 in new buildings and by 2020 Economy 7 will be completely banned in both those countries.
Further, Economy 7 SAPS (2013) coding will make it more unattractive for architects to specify night storage heating in new build domestic properties.
Finally, the elements in Economy 7 are partially exposed to the air as the bricks simply surround the elements, they do not, as is sometimes believed, encase them. As the heating elements cool, dust particles in the air settle on the elements and this dust is burned off as they again heat up. The burning of the dust and other impurities is noticeable by smell and is certainly a cause of an allergic reaction in a minority of people, usually children.
There has been some speculation that this burning off of dust may be carcinogenic however there is no evidence whatsoever that this is the case.