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Home Heating Controls For The Low Carbon Economy
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| The need to constrict the consumption of carbon fuels, and the global-warming ‘greenhouse gases’ they produce, is ever more important to our society. Today’s media constantly bombards us with reports of ice caps melting faster than expected, warnings of wildlife extinctions, prophecies of catastrophic weather conditions and predictions of disastrous climatic changes. What should be done? |
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| The UK government has issued a White Paper setting out projections for a low carbon economy, with carbon emissions into the atmosphere being reduced by 60% by the year 2050. Many other countries are equally concerned. Home heating In the UK, dwellings create around 27% of all emissions of carbon dioxide - the major part of this from home heating. Energy consumption in this sector clearly needs to be controlled.
Of course, we can all limit the use of energy in our homes simply by manually switching off the heating system when we feel the time is right. Unfortunately, few of us possess the self-discipline to maintain such a regime and, even if we did, likely results would be haphazard at least.
No! The solution is to use advanced automatic heating controls that maintain essential comfort levels while ensuring no energy is wasted at inappropriate times or at unnecessarily high temperatures.Controls and Regulations Domestic central heating in the UK really began around the middle of last century when a set of controls typically consisted of an electro-mechanical timer, a bi-metal room thermostat, a cylinder thermostat and, if you were lucky, a pump or motorised control valve.
Since then, all types of products – boilers, radiators, valves, pumps and controls – have evolved considerably, much aided by the advent of electronics.
A ‘minimum’ heating controls set now typically includes a full programmer allowing independent control of heating and hot water, a room thermostat, a cylinder ‘stat, TRVs, and a pump. Provision is required for an electric interlock that prevents the boiler firing if no demand for heat exists. Also, the latest Regulations call for separate zoning of living and sleeping areas.
Regulation of the way houses are heated has evolved through the mandatory requirements of the Building Regulations, Part L, Conservation of Fuel and Power, the latest version of which calls for high-efficiency condensing boilers in all new or refurbished dwellings that use ‘wet’ central heating systems.
All these requirements are easily met for new-build dwellings. 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, depending on what temperature controls are fitted, this may not be the case.
The truth is that condensing boilers can only deliver peak performance while running in the condensing mode.
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 carried out have shown that such controls may only permit the condensing mode to cut in rarely.
Electronic room thermostats were shown to perform better, particularly those equipped with chrono-proportional control capability.
As opposed to the temperature-event based On/Off cycling of a traditional room thermostat, chrono-proportional control 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 produce reductions of 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, checks should be made to confirm that any installed room temperature controls allow condensing 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 programmable room thermostat. |
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