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The Need For Changes in Home Heating Controls
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| Controlling the consumption of carbon fuels, and the global-warming ‘greenhouse gases’ they produce, is vital to our society. This particularly applies to the domestic sector where heating controls are under scrutiny to ensure essential future energy-savings can be achieved. |
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In the UK, dwellings create about 27% of the nation’s carbon emissions and, of these, around 75-80% can be attributed to home heating. As energy costs and environmental concerns increase, the need arises to re-evaluate all methods of preventing fuel wastage.
Heating our homes is an essential life-supporting requirement but we have a duty to ensure that our boilers fire only when necessary, and that home temperatures are maintained at the minimum levels commensurate with desired comfort. All previously acceptable areas of energy-wastage, however small, need to be eliminated.
This requires advanced automatic heating controls and, in some cases, different control techniques. The latest energy-saving controls include programmable room thermostats that allow different room temperatures to be set for different periods throughout each day, programmers with optimum or delayed start functions and new control modes such as chrono-proportional to replace the traditional On/Off method.
Such new products and techniques need to be blended in with proven traditional controls for optimum effect.Controls and Regulations Stringent Building Regulations govern the essentials of fuel and power conservation and the Government’s White Paper on energy points the way ahead to essential energy savings areas.
In the 1950’s, a set of heating controls typically included an electro-mechanical timer, a bi-metal room thermostat, a cylinder thermostat and, possibly, a pump or motorised control valve.
Since then, driven to a large extent by statutory regulation, all types of energy conservation products – boilers, motorised valves, pumps and controls – have evolved considerably through the use of electronic technologies.
Today’s ‘minimum’ heating controls set now typically includes a full programmer allowing independent control of heating and hot water, a room thermostat, a cylinder ‘stat, Thermostatic Radiator Valves (TRVs), and a pump. An electric interlock arrangement to prevent the boiler firing when there is no call for heat must be provided. Furthermore, the latest Regulations call for separate control zoning of living and sleeping areas.
Regulation of the way houses are heated has evolved through the statutory requirements of the Building Regulations, Part L, Conservation of Fuel and Power, which now specify high-efficiency condensing boilers in all new or refurbished dwellings with ‘wet’ central heating systems.
These requirements are easily met for new-build dwellings. However, refurbishing older heating systems may not be so straightforward.Refurbishment Replacing existing boilers with new mandatory condensing types should theoretically produce a 10-14% improvement in system efficiency. However, any existing temperature controls may have an adverse bearing on this.
Condensing boilers can only deliver peak performance while running in the condensing mode. Unfortunately, many domestic room thermostats have comparatively slow response rates (i.e. some electro-mechanical types) that inhibit condensing from occurring for much of the boiler’s operating time. In fact, tests have shown that such controls may only rarely permit the condensing mode to cut in.
Electronic room thermostats demonstrated better performance, particularly those equipped with chrono-proportional control capability.
Chrono-proportional control, as opposed to the temperature-event based On/Off cycling of a traditional room thermostat, regulates the amount of time for which the boiler fires. In operation, each hour is split into sections (usually 3) and the controller calculates the proportion of these periods for which the boiler needs to fire to maintain desired comfort levels. This provides a closer control band and faster reaction to temperature change, resulting in improved energy savings and better home comfort.
The tests indicated that using On/Off electronic room thermostats, in place of electro-mechanical types, can save over 2% in both energy cost and carbon emissions. Moreover, the use of chrono-proportional thermostats can push these savings up to 10%.
Consequently, when fitting a replacement boiler, it should be checked that any installed room temperature controls allow boiler condensing mode to be achieved for most of the boiler’s operating time. If they do not, then ideally they should be replaced with either an appropriate electronic room thermostat or, for even greater savings, an even more versatile chrono-proportional programmable room thermostat. Such thermostats are a small investment giving big savings for the customer. |
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