Main Types Of Heating Appliances

Heating appliances fall broadly into two categories: boilers and power units that provide full or partial central heating and fixed or portable appliances, of which there is a wide variety, that can be used almost anywhere in the house either independently or to supplement the central heating.

Electric heaters. Storage radiators and storage fan heaters rank really as heated structures supplying a form of central heating. Also available is a wide range of direct-acting electric room heaters with immediate on or off flexibility. As no fuel is required and there is no combustion, most heaters are portable and can heat any area that has a power point.

Loadings of electric heaters range from 600 watts to 3000 watts. Models with two or more electrical elements mostly have multi-switch control to provide a variable heat output. Portable models include radiant fires, convectors, combined radiant convectors and fan heaters. The fan of a fan heater can be switched on independently of the heater to circulate air in a room on a close day but without reducing the air temperature.

There are many radiant and convector models made for wall-mounting while others, designed for permanent positioning, can serve as the focal point in a living room instead of a solid fuel fire. Other non-portable heaters include oil-filled radiators. Panel heaters, skirting heaters and convector heaters.

Gas fires. Modern gas fires provide effective heating within a few minutes of being lit. The convected heat emitted is gained from hot combustion gas passing through the heat exchanger and the glow of ceramic bars termed radiants. The convector section produces warm air under adjustable or thermostatic control. The heaters can usually be fitted into existing fireplaces, some models providing hot water via a back boiler.

In hallways and other areas where no flue is available. Flueless gas heaters can be installed. Since a flueless convector has a limited output, a balanced flue convector is a solution where a larger heat output is required for background heating. With a balanced flue convector, waste gases are piped away through a balanced flue outlet in an external wall. A convector of this type sited in the hallway could distribute background heating not only to the hallway but to the staircase, landing or other traffic areas within range. Supported by local heaters, it is also suitable for an open-plan living room.

Solid fuel heaters. The traditional solid fuel room heater is, of course, the open fire. Modern solid fuel appliances are usually designed to burn smokeless fuel. Unlike the open grate, which has little means of controlling the rate of burning, the modern unit has a controlled air supply and, in some cases, an integral gas lighter for quick ignition. Some room heaters are made to be set into a wall; others are free-standing. A back boiler much extends the scope of some models, providing domestic hot water or partial central heating or, in the case of high output versions, powering all the central heating for a small house.

Open convector fires are set into the back of a fireplace. Air from the room flows continuously around the hot sides and back of the fire and returns into the room as warm convected air. A throat restrictor in the unit minimises the amount of warm air lost up the chimney. This type of unit has the advantage of producing both radiant and convected heat.

Oil heaters. These room heaters use paraffin (kerosene) treated so that it burns without odour. They are portable and are available in three forms — radiant, convector and combined radiant/convector — and in a wide range of models in various designs. But all operate in one of two ways.

The wick-fed heater has a wick immersed in the fuel container and the fuel rises to the top of the wick by capillary action. The rate of burning and therefore the heat output depends on the amount of wick exposed and is regulated by turning the wick up or down. It is important to keep the wick trimmed and to ensure that the level of the fuel in the container does not drop too low; otherwise the wick itself will burn and the heater will smoke.

The second type of oil room heater operates on the drip feed principle. Paraffin is fed into the burner via a valve from an inverted fuel container standing in a bowl. You must keep this type of heater absolutely level and make sure that the fuel container is correctly seated: otherwise the heater will not operate properly and could be dangerous.

Heat output varies with the model and is expressed in watts or kilowatts, as for electric heaters. The number of hours of heating that one filling of paraffin will give depends on the capacity of the fuel container and the rate of burning. You should find out how long the heater will operate from a full container so that there is no risk of its running dry when left on for an extended period.

Portable oil heaters do not need a flue. But some radiant/convector models can be fitted into a fireplace to operate a back boiler. There are some models that can circulate convected warm air to other parts of the house by means of a discharge fan wall-mounted in the room containing the heater. Larger models can be fed from an outside storage tank.

Caution. If a portable oil heater is knocked over accidentally, there is the danger that it could start a fire. A heater must not be left burning in a room where young children are alone. And care is necessary when handling paraffin and refilling the container.

Water heating

Most “wet” central heating systems can be controlled so that during summer months the house heating is cut off but the boiler or power unit continues to provide the domestic hot water. Where an independent water heating system is necessary or preferred, there are gas or instantaneous hot water boilers which can be wall-mounted above the kitchen sink or the bath. These are useful if you need hot water quickly. Useful, too, is an electric immersion heater fitted to the hot water cylinder (or tank) in the house. It can serve as the only regular supplier of hot water for all domestic purposes or as a standby when, for some reason, the central heating and water heating boiler is not operating.

The immersion heater can be switched on or off and is thermostatically controlled. If you use it regularly, there is little saving in electricity to be achieved by switching it off for periods (e.g. overnight) when hot water is not being drawn, provided the hot water tank is well lagged with a thick insulating jacket. Such heat as does escape from the tank will air laundered linen if the tank is sited in a cupboard.

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