Heating and air - conditioning

People are comfortable when they are neither too cold nor too warm and when the air around them is neither too dry, nor too damp and is not stuffy or dusty. To bring about these desirable conditions the heating or air conditioning apparatus must be capable of maintaining the following conditions outside may be.

For adequate heating when it is cooled outside the heating plant, in­cluding the necessary ducts, registers, piping, radiators, etc, must be able to keep all the rooms at 70 degrees, even if it is 20 or 30 degrees below zero outside.

To avoid stuffiness, the air around should be given a certain amount of motion. Under winter conditions this must be sufficient to distribute the heat uniformly throughout the rooms. It must not be too cold at life floor nor too hot at the ceiling. A stove causes the hot air around it to rise up to­ward the ceiling and cooler air to flow toward the stove. A radiator acts in this respect like a stove. Warm air registers bring heated air into a room with a certain motion or velocity which imparts movement to the air al­ready in the room. An outlet for air should be provided in order to have good ventilation. In summer - time such greater air -motion is needed enough to change the air in the room completely from 3 to 10 times per hour. Sometimes a fan is placed in the attics to blow the warm air out and to cause the cooler night air to flow it through open windows. When this is done air in the house can be expected to be changed completely every 2 or 3 minutes. When air is brought into a house from outside, heated in a fur­nace and distributed through all the rooms, it ought to be cleaned by passing it through «filters» before it enters the furnace. These filters must be capable of straining out from the air all dust, soot and other impurities. Filters should be so installed that they can be easily replaced. Cleaning the air this way prevents the dirt from entering the house and soiling the walls and furniture.

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