GAS FIRED SYSTEMS
VENTED ROOM HEATERS:
These heaters can be wall-mounted or standing and provide heat by heating fuels. The heat can be provided by the means of convection or radiation there by dividing the types of heaters into 2 types: convective heaters and radiant heaters.
These heaters are termed as vented heaters because they are usually installed with vents or connected to chimneys so as to provide sufficient air for combustion. The major advantage of these types of heaters is that they do not take up room air for combustion.
HEATERS WITHOUT VENTS:
These heaters do not have the convenience of vents and as a result they end up utilising the room ambient air for combustion. This leads to a drop in oxygen level in the space and it is because of this reason that these heaters are equipped with technologies that stop the working when the oxygen level of the room drops below the required set point
CATALYTIC HEATERS:
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These heaters are relatively new compared to the traditional ones. Catalytic room heaters provide heat by combusting the gas (fuel) in the presence of a catalyst and oxygen. The combustion happens without flames and takes place on a fibrous material that is wrapped around a conducting electric coil.
Initially the electric coil is supplied with electricity so as to preheat the catalyst followed by switching on the gas supply. The gas then begins to burn and provide heat and continues to do so even after the power supply is cut off.
Catalytic heaters have major safety feature due the flameless ignition.
The mode of heat transfer used by these heaters is both convection and radiation.
FURNACES:
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Furnaces are generally used as central heating systems that generally requires ductwork. The basic principles on which these furnaces work on are roughly the same. Air that is to be heated and supplied to the room is passed over a heated element (usually coils or pipes).
There are usually 2 vents that are provided so as to aid the combustion process. One brings in fresh air for burning and the other takes out the flue gases. If these vents are not provided the furnace will devour the ambient room air depleting the oxygen level of the room.
There are broadly 3 types of furnaces namely Gas fired, Electric and Oil fired furnaces.
The difference between the above mentioned furnaces is the method that is employed to raise the temperature of the heating elements.
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Gas Fired Furnaces burn natural gases like LPG, etc. to heat the supply air. The flame produced is controlled via thermostat in order to maximize energy savings. The heated gas is driven into the tubes via a draft fan. When supply air is passed over these tubes it gets heated and is thus supplied to different rooms. The draft fan provides enough -ve pressure to pull fresh air from outside to support combustion as well as sufficient +ve pressure to eliminate the flue gases.
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Electric Furnaces use electric resistance to heat up the coils. When supply air is blown over the coils, they get heated and are supplied to the room.
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Oil fired Furnaces make use of compressed oil. This oil is then spayed into tiny droplets with the help if a nozzle and ignited. The flame produced is used to heat up the supply air and then distributed throughout the building .
ELECTRICAL SPACE HEATERS
Electric space heaters make use of the heating effect of electric current. Current is passed through a heating coil whose electric resistance is very high. Both convective and radiant heating can be obtained through these heaters.
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Radiant heating increases the temperature of the objects by emitting radiations that are then absorbed by these objects.
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In convective heating the ambient room air is heated so as to provide a comfortable environment. Radiant heating is gaining more popularity these days because heat loss in convection is more due to infiltration losses or opening a door.