Ceiling Heating elements are mounted in the ceiling between thermal insulation and ceiling covering. The thermal radiation from the ceiling heats in first place the floors, walls and other surfaces in the room - in traditional heating systems the air mass of the room is heated first .This leads to remarkable advantages: Ceiling heating is economic, healthy, safe, easy to control and, above all, comfortable!

 

Introduction

The families of today have a lot of demands for their home. They expect it to be secure, safe, easy to furnish and warm. All facilities in the house must be reliable and easy to control. On the other hand, all this - the basic investments as well as the comfort of the daily life - must be achieved to an economic price.

Probably one of the most overlooked matters of our building process is how to heat our homes economically and efficiently. By choosing the right heating system and designing it carefully one can not only affect the economy of the house but also increase its living comfort.

Many sources of heating energy are available: oil, coal, gas, wood and electricity. All of them have

their advantages but when criteria such as low basic investment costs, easy controllability, good adaptability, almost absolute cleanness, high comfort and very moderate running costs are taken into consideration, one easily comes to the conclusion that direct electric heating is today's - and tomorrow's -choice.

 

Principles of electric heating

Electric heating principally works with electric current. The electric energy is converted to thermal energy which we usually call heat. The heat provided by the electric heating system is then - directly or indirectly - used to heat the house.

 

Indirect electric heating

A typical example of indirect heating is a system where water is heated with electricity in a boiler and then circulated to radiators throughout the house releasing heat. This system is normally charged at night using low-cost off-peak electricity. The main disadvantages lay in slow control response due to low circulation of water and low efficiency due to heat loss in the piping.

A direct heating system is always more efficient than an indirect one as the room is heated directly without a heat-transferring medium. The investment costs (boiler room, boiler, piping and- radiators) are high. The system also needs annual service.

Direct electric heating

A direct heating system generates heat and directly releases it to provide continuous warmth to a room. As there is no heat-transferring medium to be heated first, a direct heating system can be controlled swiftly and easily. The energy efficiency is also much higher than in an indirect heating system. A direct radiant heating system transfers heat in the form of infrared radiation (thermal radiation) to the surfaces of the room and to one's skin. This creates a sensation of being warm and comfortable, even though the air temperature in the room may be some degrees less than normal. The basic investment costs remain relatively low and there is no need for annual service.

Direct electric heating systems

The figures below show all the commonly used direct electric heating systems: radiator, ceiling and floor heating. They show also the different ways to direct the heat from the heating source to our living environment. The heat of radiators warms the surrounding air this is called heat conduction or heat transfer. The heat produced by ceiling heating is directed downwards as heat radiation. The heat from the floor is partly radiated and partly transferred to the room.

Radiator heating

The radiators heat the air mass of the room. Warm air rises

The traditional radiator heating systems heats in first place the air mass of the room. The warm air rises upward and causes draught. The warm air also tends to remain near the ceiling causing temperature differences in the room which creates a sensation of cold. The usual response to this is to increase the heating power. This dries the air and causes an uneconomical distribution of heat in the room.

 Radiant Ceiling heating

The heat from the ceiling radiates downwards and heats in first place the surfaces

Ceiling heating elements are mounted in the ceiling construction between thermal insulation and ceiling cladding. The thermal radiation from the ceiling heats in first place the floors, walls and other surfaces in the room. The heat from these surfaces is then transferred to the room which guarantees an even distribution of heat.

With radiant system the air temperature can be kept some degrees cooler than with conventional systems. The air is fresh, cool and healthy.

 

 Floor heating

The heat from the floor partly radiates and is partly transferred to the room.

The heating energy is partly transferred and partly radiated into the room. Floor heating is especially suitable for wet areas like bathroom, toilets, sauna and kitchen but is used in other rooms as well.

The heat from the floor heats the air and radiates upwards.

Combined Ceiling and Floor Heating

The heat radiates from the ceiling and from the floor

With a combined system the best properties of both systems are utilised. The area of the heating source is wider creating a more even and comfortable distribution of the heat. The room thermostat is connected as a group to both ceiling and floor elements to ensure that the combined heaters work as a whole unit.

 

BASIC DESIGN CRITERIA

Energy Efficient Design and Construction Method

To achieve optimal comfort, efficiency and economy, a systematic approach to heating system design is necessary. This paper describes the Energy Efficient Design and Construction Method through examples where all the affecting factors are discussed.

 

What is a heating element

An heating element consists of metal foil resistors laminated between two plastic sheets. When a voltage is connected to the element, the electric current heats the resistors.

The elements are supplied in several modular widths with a fixing area between the resistor modules.

The resistor filaments of an element are in series. This means that if one resistor filament in a heating element is damaged (for example, through a nail) the current circuit is broken and there is no danger of overheating and catching fire. This makes heating elements extremely safe.

Do not split the elements. If you have to cut an element, do it when the element is rolled. Never cut the element closer than 6 mm from the metal filaments!

Don't split this elements.

Don't cut through the resistor

Choosing the heating method

The choice between coiling and floor heating is based on the covering materials, total heating load of the house and on the other hand, on personal preferences. Most people prefer the sun-like feeling of ceiling heating. Nevertheless, for some people it is more important that they feel the warm floor under their feet.

Ceiling heating is suitable for all rooms where the thermal resistance of the ceiling material does not exceed the maximum permitted values.

Floor heating is mainly for wooden floors (parquet or boards). Note that an air gap must be left between the floor heating element and the floor covering.

When the heating load is so high that the whole demand elements can not be covered with 60 W/m2 floor and the 90 W/m2 elements are for some reason not permitted, a combined system with ceiling elements is recommended.

 

 

Important factors in the design

The following factors should be taken into account as a basis for the heating system design. The importance of ensuring a high standard of thermal insulation and thus preventing air leaks is essential to the economy of heating and comfortable living.

The level of thermal insulation and the total heating load depend naturally on the climatic conditions. This does not only mean the temperature - if the house is in an open area where it is exposed to winds, the requirements for heating are much more demanding.

A good thermal insulation is particularly important in a house heated with elements. This is due to operational demands of the Radiant Heating system. In a poorly insulated building the heat radiates outside as well as inside. To prevent this, an adequate thermal insulation throughout the whole building is essential.

Draught is an unwanted flow of air, often occurring through small gaps and openings in a house. These air leaks mean wasted energy and money through increased heating and cooling costs. Draught makes homes uncomfortable to live in because they cause localised chilling making one feel cold even if the overall room temperature is comfortable. Air leaks can account for 20% of heat losses in a home. Therefore it is very important that the whole house (walls, roof and floor) is built tight.

The most important source for heat losses in a house are the windows. Double glazing is an excellent way of protection against heat losses through window panes. You can add an extra sheet of insulated glass to your existing frame. This is a very effective form of protection. Look also for gaps between window and door frames.

Why choose radiant heating:

• no noise
• less air movement
• no service required
• less draught
• small purchasing costs
• less dust movement
• economical to install and run
• easy and individual room temperature control
• feeling of warmth even in lower room temperature

  Control design

Heating system is easy to control through a thermostat placed in each room. Attach the thermostats or gauges on internal walls at a height of 1.4 - 1.6 m in places where there is no draught, preferably as far from windows as possible.

The heating system can also be controlled through a central computerised control system. The temperature for each room can be set periodically in advance and the control system regulates the temperature due to the preset schedule - the sleeping

rooms can be cooler during working hours and there is no need for full heating in the living room during the night.

Designing the heating system

It is good practice to prepare a plan (layout of a house with element positioning and specifications for electric works) before the installation is started. This plan shall be done by a qualified person and shall be presented for approval according to local construction and electrical regulations.