Heating

There are three major ways via which heat energy can get transferred from one entity to another. They are:

  1. Radiation: In this method, there is no physical contact between two bodies and heat gets conveyed from hot body to a cold body by means of a transmission medium.
  2. Convection: In this method of heat energy transfer, the transmission medium is generally air or water.
  3. Conduction: In this method, the bodies are actually kept in contact with each other for transfer of heat energy.

 

Heat Definitions

Sensible Heat

The amount of heat needed for shifting the temperature of any body is referred to as sensible heat.

Latent Heat

The amount of heat put into use for shifting the liquid state of a chemical to its gaseous state is referred to as latent heat.

Saturation Temperature

The point at which saturation takes place or the liquid starts boiling, i.e. the saturation temperature point or boiling point of a substance tends to increase or decrease in direct proportion to the pressure. For example, the saturation temperature of water goes beyond 212 of, when it is heated under high pressure as in case of boilers. “When heat is added to saturated steam out of contact with liquid, its temperature is said to be superheated.”1

Super Heat

Superheat is a term that refers to higher temperature steam, as a result of a second special steam heat exchanger in the boiler that allows steam pressure to increase.”2
This type of steam which is extremely dry in its form is generally represented as degrees above saturation. Its unit of temperature is known as degrees of superheat.

 

Heating Systems

Nowadays, various kinds of heating systems have been developed that can be installed to meet our both home heating and cooling needs. A heat pump is the most basic technology amongst all. Some other common heating technologies are listed below:

  1. Furnaces and Boilers: These are the most ordinary systems employed for home heating purposes.
  2. Wood and Pellet-Fuel Heaters: In this method of home heating, biomass and waste materials are utilized.
  3. Electric Resistance Heaters: This method is considered to be extremely costly for home heating needs.
  4. Active Solar Heaters: This method of home heating utilizes solar radiations for air and water heating. These systems are often employed to meet the supplementary heating requirements in a building.
  5. Small Space Heaters: The efficiency of these systems is less as compared to central heating systems. However, they result in great energy savings when applied in a recommended manner.

 

Types of Heating Systems

Five major types of heating systems include:

Radiant Heating Systems

These heating systems can employ variety of fuel sources for heat generation purpose such as electrical power, boiler systems, solar radiations, and even wood and pellet-fuel heating also. Major advantages of radiant heating systems include their capability to generate easy and natural heat inside a house. These systems are usually designed in such a way that heat energy gets transferred via hot water tubes mechanism positioned beneath the floor. In some designs, these tubes are mounted in ceiling sections. A fuel operated boiler or a heating stove is used for the production of hot water in these systems.
Three major limitations offered by these radiant heating systems are given below:

  1. These systems provide very slow heating in a room since the radiant heat gets generated only after heating and then circulating water via the boiler tubes.
  2. Owing to the complicated tubing mechanism used in these systems, the installation and maintenance cost of these systems gets very high.
  3. Besides, these systems do not comprise the feature of air conditioning or cooling. A separate ductwork system would be needed to attain the cooling facility.

 

Hydronic systems

Unlike other heating systems, these systems function by circulation of hot water instead of steam. They are also referred to as hot water baseboard systems. Their operation is very much similar to radiant heating systems, where the major source of heating is regarded as boiler.

The boiler produces hot water which is then passed via tubes positioned in baseboard heating units. These heating units need to be coupled to the room walls in the house. Major fuel sources consumed for heating purpose in these systems include electric power, oil and natural gas etc. This technology of home heating does not create much noise and is found to be extremely efficient. It can be granted with the features of individual room temperature control.

However, precautions must be taken to keep the baseboard units uncovered by curtains or furniture for avoiding trouble for some consumers. Besides, just like radiant heating systems, the heating operation of these systems is not very fast. Also, they are not designed to provide home cooling services.

Forced air heating systems

It is the most basic type of system found in residential buildings. It is also popularly referred to as central heating system since it occupies a central position in the home, where all the filtration, humidification and dehumidification processes take place. “It works by heating air in a furnace and then forcing the air out into various areas of the home through installed ductwork and vents.”3
The various sources which can be employed for heating air consist of electric power, natural gas, propane and oil etc. This system is capable of meeting both home heating and cooling needs; hence frequently employed in regions where both are required.
There are few disadvantages associated with the use of these systems which are mentioned below:

  • The installation of these systems in old structures is considered to be very complicated since the necessary ductwork tends to seize an area in walls. Besides in new buildings, this system can be implemented only with extra care and preparation.
  • Due to the noise factor involved with its furnace system, it may cause nuisance to the home surroundings.
  • Circulation of air inside the building causes the allergens to move about the whole house.
  • For trouble free performance, the air filtration mechanism inside these systems needs to be periodically maintained.
  • Owing to the high maintenance costs involved, the usage of this system proves to be highly expensive.

Steam radiant heating systems

These systems make use of steam radiators for room heating purposes. They consist of one or two pipes and employ sources like electricity, oil, or natural gas for heating up water. “While these units may be energy efficient and warm a room quickly, they can be inconvenient for furniture placement, as the walls and surrounding area must be clear to avoid fire hazards.”4
Moreover, the appearance of radiators is not liked by some individuals in their homes. Hence, they prefer to go for some other pleasant looking heating system. Also, these systems are not capable of providing cooling facilities.

Geothermal heating systems

These systems are being recently developed to solve heating and cooling problems inside buildings and homes. Their installation cost tends to be very high. However, they utilize heat from the ground for controlling temperature which makes them extremely valuable for causing reduction in cost related with the home heating and cooling needs.

 

Selection of a Heating System

Following points must be considered carefully while making a decision about home heating systems:

  • Power requirements of the heating system
  • Cost of purchase and installation
  • Since central heating system alternatives available in the market offer combined heating and cooling services, one must make a choice depending upon his/her own particular requirements.

 

References

1. Saturartion Temperature
2. Superheat
3. Forced Air Heating
4. Steam Radiant Heating

 

Sources

Arvanitakis
Energysavers
Wisegeek

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Posted in Heating