CA1316349C - Heating system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An improved heating system uses a unique damper arrangement for distributing intake flows to two blowers.
The arrangement provides full flexibility in adjusting the composition of the air circulated through a building and allows flushing of the system when desired. Heat energy is advantageously salvaged in the preferred heating system.

Description

131~34L9 TITLE: HEATING_SYSTEM

FIELD OF THE INVENTION
_ The present invention relates to heating and ventilating systems suitable for either commercial or residential purposes. In particular, the invention is directed to such systems which allow energy efficient exchange of interior and exterior air.
ûver the past ten years, energy conservation measures have resulted in sealing of buildings whereby exchange or circulation of air within the building has been greatly reduced. It is generally accepted that at least a 10% requirement for makeup air is required and, in many cases, this is now being satisfied by air exchange through doors and other openings in the building. The effective sealing of windows and eliminating drafts has greatly reduced the exchange of air in this manner and problems have occurred where buildings have been effectively sealed whereby the amount of makeup air is not sufficient to remove odors and/or humidity, as but two examples.
United States Patent 4,655,278 discloses a particular system which causes air under pressure to be circulated to opposite heat exchanges of a heat pump and effectively provides for makeup air. In this case, ducts are provided for the passage of the makeup air and they suggest these can be controlled by dampers. Although this system does accommodate some air exchange, it does not allow a significant variation in the air exchange and the arrangement is complicated and relies on air that has 3û already been pressurized to be fed to a suction side of a different blower. In this case, the energy required to pressurize the air is effectively lost. In addition, this patent teaches various means for effectively limiting the temperature range in which the heat pump operates and as such, reduces the design requirements for the heat pump system. In effect, the patent teaches the use of heat , , ~31~3~
salvaging for modifying the extreme temperatures that the heat pump system would otherwise see Design requirements for heat pumps are more critical in Canada and the northern United States where extreme temperature ranges are common for a large portion of the year. These design requirements make the demands on the heat pump system more rigorous.
These design requirements are fully described in United States Patent 4,655,278.
Efficient energy conservation and design of a heating and ventilating system must recognize the widely differing characteristics of a building. For example, there are portions of the building, washroom exhausts, kitchen exhausts, as but two examples, which are normally separately vented. This is done to avoid contamination of the overall lS air of the system, however, makeup air is required to accommodate the amount of exhaust vented to atmosphere. It can be appreciated that these are not constant and fluctuate throughout the day, depending upon the building usage and the number of occupants within the building. Other factors come into play such as the use of the building by occupants which in the case of office buildings, is concentrated during the day and in the case of homes, is concentrated in the evening. Occupants contribute heat to the building while also increasing the required makeup air. Thus, the heating and ventilating system should be flexible, accommodate variations in the demand for makeup air, effectively salvage energy from the air to be vented, and preferably allow for selective adjustment of the amount of makeup air as the requirements change. For example, complete purging of the building, ie. venting all of the return air and bringing in 100% makeup air, may be desirable for a limited time, however, the energy within the return air should not merely be dumped to the atmosphere, it should be effectively salvaged prior to being vented to the atmosphere.

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., 3 ~ 9 The heat pump c~cle effectively transfers energy from one environment to another environment by means of heat exchangers. In all cases, a fluid circulation system is employed and a compressor is used for circulating of the fluid about the heat pump. In most cases, there is residual energy in the fluid and, according to the present invention, a portion of this energy is removed and used for secondary heating.
The present invention also makes it possible to lû provide a simple means for distributing air within a heat pump by means of a air plenum chamber and a damper disposed therein which effectively distributes the return air and outside air to the heat pump along one of two paths.
Depending upon the position of the damper, the percentage of inlet and outside air can be varied in each of the two air flow streams.
United States Patent 2,401,560 discloses a heat pump system having a host of dampers which cooperate to allow adjustment in the ratio of makeup to return air recirculated throughout the system. This structure, although satisfying various provisions, is somewhat complicated due to the host of dampers.

SUMMARY OF THE INVENTION
The present invention relates to improvements in heating systems where the heating system has a first heat exchanger and blower for processing a first flow of air, and a second heat exhanger and blower for processing a second flow of air, with the heat exchangers working in cooperation with each other for the transfer of heat energy between the air fIows. Two separate sources of air flow cooperate with an adjustable damper means of the air flow mixing means on the suction side of the blowers whereby the first and second air flows are simultaneously oppositely varied to increase or decrease the amount of air originating from each of the ~ .

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~316349 separate sources of air flow by means of changing the position of the damper means.
In a forced air heating or ventilating system, according to the present invention, a first blower circulates air through the system and cooperates with aiI
mixing means having connected thereto an outside air source and a return air source separated by an adjustable damper means for determining the mixture of outside and inside air fed to the suction side of the first blower. The damper means is adjustable to simultaneously vary the mixture of outside and inside air fed to the first blower by causing the appropriate portion of inside air to be exhausted from the system.
According to a preferred aspect of the invention, the damper means is adjustable between the limits of essentially 100% outside air in the mixture and essentially 100% inside air in the mixture. In most cases, a capability of 90% either inside or outside air in the mixture would be sufficient and would clearly surpass any of the known systems having a damper means which simultaneously adjusts both inside and outside air.

BRIEF DcSCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in the drawings, wherein:
Figure 1 is a schematic view showing the structure of the heat pump and the fluid circuit of the heat exchanger in cooperation with secondary heat storage devices;
Figure 2 is a schematic view of a modified heating system; and Figures 3 and 4 show an~alternate damper arrangement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be described with respect to the overall system of Flgure 1 and then the modified systems of .
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Figure 2 can be understood as they rep~esent simplifiedversions of the complete system of Figure 1.
The system of Figure 1 shows a heat pump 2 having a first heat exchanger 4 and associated blower 8 and a second heat exchanger 6 and associated blower 10. These represent the opposite heat exchangers of the heat pump and the second heat exchanger is designed to have outside air essentially pass thereover and the inside heat exchanger 4 is principally designed to have inside air pass thereover. The amount of inside air and outside air, which is fed to the suction side of each of the blowers 8 and 10, is controlled by the movable damper 12 disposed in the air distribution plenum 1~. The plenum 14 is connected to the suction side of each of the blowers 8 and 10, and the suction side of each of the blowers are separated by the damper 12.
In the position shown in Figure 1, the damper directs all outside air, shown by arrow 15, to the suction side of blower 10 and all inside air, shown by arrow 18, to the suction side of blower 8. By rotating the damper about 2n its central pivot 20 in a clockwise direction, a portion of the inside air 18 can now gain access to the suction side of blower 10 and, similarly, a portion of the outside air 16 can gain access to the suction side of blower 8.
This movement of air past the damper will pressure equalize the system and automatically cause in more outside air being fed as makeup air to blower 8, if and when required by the building, for example, the positive exhaust which is vented as indicated by arrow 22 to blower 10. This will initially tend to create a slight negative pressure within the building and the outside air will be under a slightly greater positive pressure and, therefore, a greater flow will occur to the suction side of blower 8 through any gap between the damper and the air plenum 1~. In this way, the system automatically adjusts for various demands of the building in that the pressure differential between inside and outside tends to result in a balancing of the pressure .
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13~l~3~9 by increasing or decreasing the amount of makeup air that passes to blower 8.
As brought out in the background of the invention, a 10% makeup air is the recommended constant amount and, in 5 most cases, the damper will always allow some outside air to gain access to the suction side of blower 8. By causing damper 12 to pivot through 90, the damper now causes the inside air to be processed to the suction side of blower 10 and the outside air to be processed to the suction side of blower 8. In this position, the building is effectively purged as all return air is being vented from the building.
Note that due to the arrangement of blowers and the arrangement of the dampe-r, this inside air is passed through the blower and similarly the exhaust air is passed through the blower and will pass over heat exchanger 6. In this way, the energy in the inside air and in the exhaust air is extracted or a portion thereof is extracted as it passes through the second heat exchanger.
An alternate shutter type damper arrangement 12a is shown in Figures 3 and 4 which can replace the rotatable damper 12 of Figure 1. In Figure 3, one set of shutters are open and the others closed to fully separate the two intake air flows, whereas in Figure 4, the opposite orientation of shutters is present whereby all inside air forced under pressure through the building originates from outside intake air 16. The shutters can be automatically controlled and adjusted to achieve mixtures between the extremes of Figures 3 and 4.
The shutter type damper and the pivotting damper of Figure 1 can be insulated to reduce heat loss and reduce condens~ation problems. Each can be automatically controlled and~adapted to close when the system is idle.
The air flow arrangement shown is preferred, but other arrangements are possible to selectively mix outside air and~return air to the blowers.

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~31~349 The heat exchange fluid medium and the circuit thereof includes a compressor 2~, an accumulator 26, an expansion valve 28 and a reversing valve 30. In addition, there is a fluid to ~luid heat exchanger 32 and a further heat exchanger 34. Heat exchanger 3~ is optional and may be used to extract heat from other sources such as a ground source water supply if available. Heat pumps which have accumulators are known and they effectively increase the efficiency of the heat pump such that it can operate at lower outside temperatures. The reversing valve in Figure 1 is positioned for the air conditioning cycle and will be briefly described.
Hot compressed gas leaves compressor 24 through line 4û and enters the top of heat exchanger 6. Air is passed under pressure through the heat exchanger 6 and serves to cool the gas and give off heat. The fluid is then passed through line 42 into line 44 and enters line 46 due to check valve 48. This is a one-way check valve and the pressure of the heat exchange medium closes the check 2û valve. Note that check valve 5û allows the heat exchange medium to pass,therethrough whereas check valve 52 stops any flow through line 45. Check valve 49 at the end of line 45 is a one-way check valve and only allows a flow out of line 45. Heat exchange medium then passes through heat exchanger 32 which is sized to effectively transfer lû0% of the heat of condensation. The amount of heat transfer will depend upon the temperature of the water being circulated on the other side of the heat exchanger and the temperature thereof. In practice, the water being fed may be brought in 3û at about 70 and may leave at about 100F. Therefore, much in the way the outside air has removed heat, heat exchanger 32 in the air conditioning cycle again removes further heat prior to the heat medium being passed through the accumulator. The accumulator further subcools the heat exchange medium prior to it Ieaving through expansion valve 28.

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Heat may be added at the exchanger 34 and the heat exchange medium passes through line 45 and enters line 54 enroute to the first heat exchanger 4. The heat exchange medium enters the heat exchanger 4 and is evaporated and thus removes heat from the inside air flow which is passed thereover by blower 8. The heat exchange medium is removed through line 56 and circulated to the accumulator 26 where further heat may be removed in subcooling the exchange medium in line 46, whereafter the gas is fed to the compressor. Thus, the heat exchange fluid medium returning to the accumulator is superheated and any residual liquid is transformed into gas prior to being fed to the compressor.
If necessary, the air fed through blower 8 may be excessively cooled to dehumidify the air as it passes through heat exchanger 4 and thereafter additional heat may be added to the air being circulated by heat exchanger 60.
This is a hot water to air heat exchanger and can be used if dehumidification of the air in the air conditioning cycle is necessary requiring excessive cooling of the circulation air By reversing valve 30, line 56 becomes connected to line 40 and heat exchanger 6 becomes connected to the accumulator. The compressor 24 passes hot compressed gas, which is normally superheated, through line 40 and it enters through line 56 into heat exchanger 4. The air discharged by blower 8 is forced through the heat exchanger 4 and heat is removed from the hot compressed gas. This hot compressed gas, having a certain amount of energy removed therefrom, is passed through line 54 and passes through check valve 48 and into the heat exchanger 32. Energy is transferred to the water system and then the heat exchange medium is passed through the accumulator 26. More heat is removed at the accumulator prior to passing through the expansion valve 28. The heat exchange medium is then passed through heat exchanger 6 which extracts energy from the outside air and the heat exchange medium is then passed to the accumulator 26 by means o~ the reversing valve 30. The heat : , , - : .
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exchange medium returns to the compressor 24 in a gaseous state.
Thus, in the heating mode, the compressed gas being discharged by compressor 24 is fed to heat exchanger 6 fiIst and, depending on how much energy is Iemoved in this heat exchanger, the amount of energy removed by the second heat exchanger 32 will be effected. For example, the temperature of the house may require more heat to be added and blower 8 could be shut down. Therefore, very little energy will be dissipated by heat exchanger 4 and more energy will be transferred to the water circulation system generally shown as 100 through the heat exchanger 32. To a certain extent, this is controlled by the temperature sensor 75 which interacts with the expansion valve 2~. Therefore, the placement of heat exchanger 32 relative to heat exchangers 4 and 6 is important.
The hot water`circulation systern generally shown as 100 includes a hot water tank 102 having an outlet line 104 connected to the normal hot water system as well as connected to the heat exchanger 60. Water is circulated through heat exchanger 60 by controlling the modulating valve 106. In one position of the modulating valve 106, line 108 is connected to the floor storage system 110 which essentially is a long length of tubing placed within a floor slab, as but one example. Thus, hot water at perhaps 140F can pass out of the hot water tank, be circulated to the heat exchanger 60 and then passed through the floor storage system 110 where it might Ieave at about 70F.
This water is then fed by pump 112 through heat exchanger 32 and is returned to the hot water tank at possibly 100F by line 114. Line 114 has a discharge somewhere approximately one-third of the way from the bottom of the hot water tank as indicated at 116. This lower discharge serves to minimize mixing of the water within the hot water tank.
Modulating valve 106, when heat is not required or water is not circulated through heat exchanger 60, provides a ~ ~ ~' ' ' .'',' , -- ` . 10 ~ 3~3~
straight path through the modulating valve into the floor slab system 110 and finally through the heat exchanger 32 prior to entering the tank by inlet 116. The hot water tank also includes a cold water inlet indicated at 120.
A ~urther modification of the system can be appreciated by considering the heating cycle ~nd the need in the winter months to provide humidified air within the house. In a heat pump, the outside heat exchanger, in this case exchanger 6, requires de-icing and as such, goes into a lû heating cycle to melt any ice on the heat exchanger~ In most cases, this water is merely dumped on the ground or directed to a drain, however, the water can be directed to the tray 130 of heat exchanger 4 from tray 132 of heat exchanger 6 whereby effectively distilled water, or water 15 not having any minerals therein or at least reduced minerals, is fed to the base of heat exchanger 4 where it can enter the air and humidify the air as it passes thTough heat exchanger 4. Such a system is preferred to existing systems where inlet water from the supply system is merely 2û passed through a humidifier and accumulated in a tray.
The heating system of Figure 2 again has a slab energy storage system 100 which cooperates with the hot water heating tank 102 much in the manner as described with respect to Figure 1. Cold water may pass through the slab 25 heating system to raise the temperature thereof prior to being brought into the hot water tank at inlet 116. This is controlled by the modulating valve 106. In this case, hot water from the tank 102 can be circulated to the heat exchanger 6û which is placed in the plenum of a furnace or 30 other heating system. The blower 61 forces air over the heat exchanger and thus extracts heat from the hot water, with the water being returned normally through the energy storage system 100. The water is circulated by pump 112.
This arrangement is also valuable for off peak heating in that energy may be accumulated in the slab heating system 100 during periods of low demand and this energy is more , . , ' , , - : :

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, effectively used during periods of high demand. For example, if this was an electric furnaceS the furnace in effect could be shut down during periods of high demand with heat being taken from the hot water tank 102 and circulated through heat exchanger 60 to provide the necessary heat for the house.
Any cold water that is required first passes through the slab heat storage system 100 and is raised thereby lowering the amount of energy required to raise it to operating temperature. In this way, the hot water tank serves as an energy storage system to smooth the energy demands of the system. This system has a more constant demand and in periods of high energy requirements, the electrical requirements can be reduced significantly. This type of arrangement has application for modifying existing heating systems, particularly electric systems where penalties or increased prices are charged for electrical consumption during high peak periods~ This system is a simplification of the highbred heating and cooling 2û ventilation system disclosed in Figure 1 which can function in a similar manner~
In addition to the system of Figure 1, it can be appreciated that other equipment can use the waste heat of heat exchanger 6 during an air condition-ing cycle. For example, a hot tub or swimming pool can be connected to a heat exchanger associated with the return of the hot water tank and extract further energy for this particular use.
Thus, the energy that is extracted from the house to keep the house cool is transferred via this system to the swimming pool which must be heated.
As can be appreciated, the present system provides positive pressure control in that the blowers 8 and 10 can be controlled to provide a slight positive pressure within the building if desired by varying the operation thereof.
It is generally found that it is desirable to run a building in a slight positive pressure rather than a negative pressure.

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13~3~9 The present system recaptures heat from whatever sources are available and effectively transfers it to another portion of the system. The system uses an air to air heat pump cycle in combination with liquid heat S exchangers which are normally more efficient. In addition, a hot water to air heat exchanger can advantageously combine with the heat pump cycle to add supplementary heat where or when required. The check valve arrangement provided at the bottom of the fluid circuit diagram advantageously lû automatically causes a correct flow of the heat exchange medium through the heat exchanger 32 which is thus useful both in the heating and cooling cycle of the system.
Dehumidification and humidification of the air systems are possible and, in a preferred embodiment, water is transferred from one heat exchanger to the other for humidification. The system also lends itself to off peak demand requirements where energy consumption during periods of high power demand are reduced~ The system, in its preferred form, has various storage systems where the heat 2û pump can operate more continuously to build up heat when the building does not necessarily require it. This heat is then used when required. It is recognized that a large portion of the energy consumption is caused during startup of a compressor and the energy required to continue to run the compressor is not nearly as significant relative to this high demand upon startup. This system allows the compressor to run for longer periods of time and thus more effectively uses the energy it requires. By use of the heat exchanger 60, once the compressor has been shut down, it is possible to provide supplemental heat without even restarting the compressor, thus further reducing the startups of the compressor~
Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that var~iations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.
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Claims (4)

1. A building ventilating system comprising a first blower for directing air flow to the inside of a building, a second blower for directing air flow exteriorly of the building, first and second interior building air intakes, an exterior air intake, and damper means for determining mixture of interior air recirculated through said first interior air intake and exterior air through said exterior air intake to said first and second blowers, said damper means being adjustable to simultaneously and equally vary such mixture, said second air intake feeding to said second blower to exhaust air from the building independently of the mixture at said damper means.

2. A system as claimed in claim 1 wherein said system is self balancing to adjust position of said damper means to bring in additional exterior air according to the amount of air exhausted from the building.

3. A system as claimed in claim 1 wherein said system includes means for heating the building.

4. A system as claimed in claim 1 wherein said system includes means for both heating and cooling the building.