Full central heating involves heating the whole of the house to a required temperature and maintaining that temperature irrespective of how cold it is outside the house. Since the boiler or central heating unit and the distribution equipment must have sufficient capacity to meet extreme outdoor conditions, the running costs of full central heating are proportionately high. Partial central heating. Commonly, the living room, dining area arid perhaps the hall are actually heated and, for most of the time, other parts of the house such as the bedrooms depend on spillage of that heat to give them some warmth.
Selective central heating.
The central heating system covers the whole house but the capacity of the boiler allows only portions of the house to be heated at any one time, usually as various rooms are occupied. Background heating. The whole house or sections of it are raised in temperature to about 55 degF (12.8 degC) and supplementary heating is used to top up this temperature as rooms are occupied. Sources of background heating include low-capacity hot water radiators, various types of electric heaters, including skirting heaters and electric storage radiators.
Local and focal-point heaters.
Small portable electric heaters are usually used for local heating — for example in the television corner of an open plan living area when the family gathers there on a cold evening. A focal-point heater is a substitute for a fire in an open grate. Electric and gas fires simulating burning coal or logs are examples. In a flueless room having no fireplaces an electric fire can be permanently fixed at any point, using a surround to simulate a fireplace. These fireplace surrounds, complete with electric fire, are available as separate items or can be home-constructed. They can be fixed either to a wall of the room or into a room-divider in an open-plan scheme.
Temperatures and controls
A central heating system is designed to provide specified temperatures in the various rooms and areas. For the living room and dining room the generally recommended temperature is 70 deg F (22 deg C). For the kitchen, hall and landing the recommended temperature is 60 deg F (16 deg C) and for bedrooms 55 deg F (13 deg C). These standards are, of course, variable according to region and siting of the house.
Different levels of temperature in different rooms and areas are obtained by selecting the appropriate sizes of radiator or, in the case of warm air systems, appropriate ducts and outlet grills. But the heater unit or boiler must be capable of providing the total heat requirements under the most severe weather conditions.
Time and heat controls.
The more sophisticated the control system, the more flexible and economical the central heating. Thermostats are geared to switch appliances on and off according to the air temperature around them.
Time switches operate at a pre-set time. A rudimentary control system might comprise a single room thermostat in the hallway or living room. A more sensitive system might consist of a thermostat in nearly every room, set for different temperatures at different times of day and night. Simple time switches will turn heating appliances on and off for two separate spells during 24 hours. More sophisticated ones are, in effect, programmers that you can set to give variations around the clock or, for example, to turn the heating on briefly once a week when the house is unoccupied.
It is generally thought to be more economical to keep the heating on, though at a lower temperature, through the night than to turn if off, since in the latter event the heating system must start almost from scratch to warm the house again.
The four heating agents to choose from are electricity, gas, solid fuel and oil. For full or partial central heating you must select one of the four. But for room heating independent of or complementing a centrally powered system you can use a combination — for example, solid fuel for the open fire in a living room and (provided the house is supplied with gas and electricity) variously gas and electrical heaters elsewhere.
Given a mains supply or generator, electricity is always conveniently on tap unless there are power cuts. It needs no bulk storage. Heating by electricity makes no noise or smell. The general maintenance required is minimal. On running costs, generalised comparisons between it and its three competitors could be misleading because of the changing cost structure of all forms of power, regional variations and, not least, the specific type and size of house that is to be heated.
Reduced price, night time electricity is normally provided by the White Meter—which is installed in place of the existing meter, and is different in that it has two registers of electricity consumption. These record electricity supplied to the home at two different rates: a day rate and the reduced night rate. Any electricity used during the night period (usually between 11 pm and 7 am) is charged at the low rate; at other times it costs just slightly more than the normal domestic tariff rate. Gas, if a supply is connected to the house, is (like electricity) on tap and requires no bulk storage.
The growing availability of natural gas is likely to keep its cost to the home consumer competitive. Small, compact central heating gas boilers can be installed indoors at eye level, saving floor space.
for central heating requires a storage tank outside the house and a feed pipe. The larger the tank the better: it will reduce delivery calls by the tanker and you may benefit from discounts on substantial quantities of oil. To banish any noise or fumes, a conventional oil-fired boiler should be sited in an outhouse but some versions have a balanced flue, enabling them to be placed indoors against an external wall.
Like oil, solid fuel (coal, coke, anthracite or composition fuel bricks) requires periodic deliveries and bulk storage. Automatic solid fuel boilers, incorporating timing and thermostatic controls, are gravity fed. In most cases they need to be fuelled only once a day, but this still involves your bringing in hods of fuel from the coal shed and from time to time removing clinker and ash from the boiler.