1. Field of Invention
This invention relates generally to a heat recovery unit for use in association with a fluid distribution system, and more particularly to a heat recovery ventilator for use in association with a central air distribution system such as a forced air heating system or air conditioning unit within a home or office.
2. Description of the Prior Art
Central air distribution systems are commonly used in commercial buildings or in residential homes. Such central air distribution systems comprise of a series of hot air ducts and cold air return ducts connected to a furnace. The furnace heats the air and a blower fan located in the furnace circulates the same through the hot air ducts, throughout the office or home, while the cold air ducts collect the cold air within the office and home and return the same to the furnace for heating.
It should be noted that air conditioning units are commonly connected to the furnace so that during the hot season, the air conditioner cools the air and a blower fan forces same through the hot air ducts throughout the office or home, and the hot air is returned through the cold air return ducts to the air conditioner for cooling.
In either the heating or cooling procedures outlined above, the circulated air becomes "stale", particularly in modern homes of offices which have been efficiently insulated so as to prevent any drafts of hot or cold air between windows, doors, ceilings or the like.
However, when ventilating a portion of the circulated air in the central air distribution systems with fresh air, heat energy or thermal energy losses occur. In the case of ventilating some hot air and replenishing same with fresh air, from the environment heat energy losses occur. In the case of ventilating air conditioned air with fresh air from the environment, heat energy losses occur.
Apparatus and various methods have been devised to transfer thermal energy from one source to another.
For example, Canadian Pat. No. 1,035,766 discloses a thermal transfer system which comprises a sealed plate containing a working fluid which is alternatively evaporated and condensed to transfer heat.
Furthermore, Canadian Pat. No. 1,002,937 teaches a unit for recovering thermal energy which utilizes a plurality of heat pipes which are disposed horizontally and filled with a volume of working fluid sufficient to cause the liquid phase to travel in either direction of gravity, and circumferential capillary grooves in the side walls of the heat pipes transport of the liquid phase vertically above the liquid level to increase the area of the liquid-vapour interphase.
Moreover, Canadian Pat. No. 1,123,690 relates generally to heat exchange systems, and in particular to a gas-to-water heat recovery system which utilizes an array of heat pipes for collecting heat from a stream of heated gas and transferring the heat onto a volume of water for the production of steam.
With the rising cost of energy there is a continuing need for systems to recover heat energy during ventilation of air which is being replenished by fresh air, particularly in central air distribution systems.