Introduction
In order to maintain standard room temperature, the heating apparatus must supply heat to replace the lost through the walls, floors, and ceilings, and, in addition, the heat necessary to warm the cold fresh air used for ventilation. Heat is lost by conduction through walls, floors and ceilings, and by diffusion through cracks around doors, windows, etc.
The purpose of heating and ventilating systems is to create comfort conditions, the environment inside the premises which is characterized by four principal factors: temperature, humidity, air purity and velocity and air motion. Heating provides the necessary temperature while ventilating is responsible for the rest.
Systematic ventilation is necessary in public buildings in which people congregate, such as schools, cinemas, theaters, etc. and provision must be made for the admission and escape of the air through flues or definite openings and for power for moving air. The air may be moved by expansion due to heat or by fans. The latter method is the one most used since it affords ventilation in summer as well as winter. Ventilation by fans may be accomplished by forcing the air into a room or exhausting air from it.
1. Heating and gas supply
Local heating is in common use in many countries. Such heating comes from fireplaces, or room heaters.
The earliest type of local heating system was the open fire within an enclosure, such as a cave or a tent. Such a fire is not satisfactory because the area heated can accumulate smoke.
If a fireplace is put at one side of a room and provided with a chimney, the smoke and combustion gases will pass up the chimney. The chimney provides a draught by which the air enters the front of the fireplace and passes up the chimney to aid the burning of the fuel. However, this draught reduces the energy efficiency of a fireplace.
Some room heaters burn gas to produce heat. These can be placed in a corner of the room and used with a fan to circulate the heated air. Such heaters should not be used without adequate ventilation to the outside because combustion gases can be harmful to the occupants of the room. Other room heaters burn paraffin and must also be vented [1].
Electric room heaters pass an electric current through a series of wires. These wires resist the electricity and become red hot. Such electric heaters give off heat by radiation and convection.
Most local sources of heat are relatively hot, compared with steam and hot-water radiators. For this reason they produce a larger proportion of radiant heat. When such large amounts of radiant heat are used, the temperature of the air in the room needs not become so hot. For example, a resistance-type electric heater called a quartz heater warms anyone in the path of its heat rays. But the heat rays do not significantly warm the air through which they travel.
2. Ventilating
Ventilation is the process and practice of keeping an enclosed place supplied with proper air for breathing. People spend about 90% of their time inside, that’s why good ventilation is important because it helps protect your health and your home. Ventilation supplies fresh air to your home and dilutes or removes stale air. There are many ways this can happen: opening windows to air out your home, turning on the fan over the kitchen range or in the bathroom, using chimneys and clothes dryer fans. Conditions such as the sour smell of garbage from a trash; a musty, gym-like smell coming from the bedroom walls; or mold or mildew in closets, or on ceilings or exterior walls; the condensation on the inside of your windows, irritation of your eyes, when you are at home may be signs of poor ventilation. It may be as simple as an overflowing garbage can or as complicated as mold growing inside walls. Whatever the case, you must identify the source before you can solve the problem. One of the easiest ways to improve indoor air quality is to remove or avoid using common sources of moisture, odors, and gases [4].
There are two basic approaches to ventilating your home: 1) spot ventilation for localized pollution sources; and 2) general ventilation to dilute pollutants from sources that exist in many locations or move from place to place.
Spot ventilation uses exhaust fans to collect and remove pollutants before they spread throughout your home. The exhaust fan is generally turned on only when the source is producing pollutants. Bathrooms, kitchens, and laundry rooms all contain obvious sources of moisture and odors. Spot ventilation may also be appropriate for home offices, hobby rooms, or workshops.
General ventilation fans run all the time to control pollutants from sources that can't be spot-ventilated. General ventilation mixes fresh outdoor air with stale indoor air to lower the concentration of pollutants (dilution). Fresh air is provided by fans blowing outdoor air into the house, which forces air out through cracks and openings (pressurizing), or by exhausting air from the house, which then draws fresh air inside (depressurizing). General ventilation can be provided in two ways: exhaust-only, and supply-and-exhaust.
Conclusion
In general, a heating system should be designed so that the water will circulate by gravity. In some installations, circumstances are such that a pump or accelerator must be used to achieve a satisfactory circulation. This should be avoided if possible.
When designing a heating system for a large building, it is usual – in the interests of economy and to ensure efficient heating – to first calculate how much heat will be needed to maintain the building at the desired temperature. Then the size of the boiler and the amount of pipe and radiator heating surface required to give out this heat will be estimated. For small systems, "rule-of-thumb" methods and past experience are generally a sufficient guide.
The overhead drop-feed system shows how the hot water from the boiler is carried as high as possible in the building, from where it falls "in cooling, through the various branch pipes and radiators, back to the boiler. In this type of system, the maximum amount of "circulating head" or pressure, would be obtained.
Ventilation is the process and practice of keeping an enclosed place supplied with proper air for breathing. Ventilation supplies fresh air to your home and dilutes or removes stale air. There are many ways this can happen: opening windows to air out your home, turning on the fan over the kitchen range or in the bathroom, using chimneys and clothes dryer fans. Whatever the case, you must identify the source before you can solve the problem. One of the easiest ways to improve indoor air quality is to remove or avoid using common sources of moisture, odors, and gases.
