CA2509571A1 - Pressure sensitive bypass defrost system - Google Patents

Pressure sensitive bypass defrost system Download PDF

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Publication number
CA2509571A1
CA2509571A1 CA002509571A CA2509571A CA2509571A1 CA 2509571 A1 CA2509571 A1 CA 2509571A1 CA 002509571 A CA002509571 A CA 002509571A CA 2509571 A CA2509571 A CA 2509571A CA 2509571 A1 CA2509571 A1 CA 2509571A1
Authority
CA
Canada
Prior art keywords
exhaust
plenum
inlet
air
supply
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002509571A
Other languages
French (fr)
Inventor
Bertrand Poirier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Sheet Metal Ltd
Original Assignee
Imperial Sheet Metal Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imperial Sheet Metal Ltd filed Critical Imperial Sheet Metal Ltd
Priority to CA002509571A priority Critical patent/CA2509571A1/en
Priority to US11/423,011 priority patent/US20070084586A1/en
Publication of CA2509571A1 publication Critical patent/CA2509571A1/en
Abandoned legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F12/00Use of energy recovery systems in air conditioning, ventilation or screening
    • F24F12/001Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
    • F24F12/006Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an air-to-air heat exchanger
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/30Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
    • F24F11/41Defrosting; Preventing freezing
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F12/00Use of energy recovery systems in air conditioning, ventilation or screening
    • F24F12/001Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
    • F24F2012/007Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using a by-pass for bypassing the heat-exchanger
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/56Heat recovery units

Abstract

A heat recovery ventilator defrost system utilizing a bypass section which supplies warm air in both channels of the heat exchanger to accelerate defrost, continue some ventilation of stale warm air, and recirculate a portion of the stale air flow, so as to warm incoming cold fresh air. When the system is in defrost mode, warm exhaust air to be expelled enters an exhaust inlet port and into an exhaust plenum. Because the air being exhausted (by way of the exhaust fan) through the exhaust plenum is under a positive pressure, the stale air will still be sucked out through exhaust passageway into discharge plenum, but also through the passive non-motorized bypass section into inlet plenum.
Further, because fresh air continues to be drawn into inlet plenum, due to the positive pressure, the warm stale air which has passed through the bypass section (flap) into inlet plenum is then drawn through the heat exchanger along the inlet passageway into supply plenum, and out through supply port into the enclosure or dwelling. In this way, the heat recovery ventilators defrost system of the present invention supplies warm air in both channels of the heat exchanger.

Description

PRESSURE SENSITIVE BYPASS DEFROST SYSTEM

FIELD OF THE INVENTION
This invention relates to air exchange ventilators for admitting fresh air into an enclosure while exhausting stale air. More particularly, this invention relates to a defrost arrangement for air exchange ventilators which include a heat exchanger to extract heat 6 from the stale air and transfer it to the incoming fresh air, and which introduces warm air in both channels of the heat exchanger to accelerate defrost, continue some ventilation of stale warm air, and recirculate a portion of the stale air flow at mild temperatures as opposed to the lower temperatures of incoming fresh air.

Highly energy efficient buildings are generally designed to avoid uncontrolled intake and out-take of air. As some air exchange is necessary to remove stale air and replace it with fresh air, it is desirable in winter to first remove heat and or energy from 16 the stale air and replace it with fresh air, and it is preferable to first remove heat and or energy from the stale air being exhausted to avoid losing this heat. A
heat/energy recovery ventilator is therefore used for this purpose.
A heat recovery ventilator includes a heat exchanger with two discrete air 21 passageways; one for stale air exhaust, and the other for fresh air supply.
As the exhaust air passes out of the enclosure or building through the heat exchanger, it gives up its heat to the fresh supply air entering the enclosure through the heat exchanger.
Accordingly, the heat is recovered in the ventilator during the ventilation process and hence the name, "heat recovery" ventilator. Note: The heat exchangers performance is dependant on the 26 difference in temperature and energy recovery unit works because of a difference in enthalpy between the two airstreams.
Problems ensue with heat recovery ventilators in situations where the fresh air supply is near or below freezing temperatures. During colder seasons, as the stale air 1 generally contains moisture, once it passes up heat the moisture will freeze in the stale air exhaust passageway or on components in the heat recovery ventilator.
Eventually, ice-build up will block the passageway, preventing or inhibiting the exhausting of stale air, or cross contamination due to flap leakage may occur; Balanced ventilation suggests that both incoming and outgoing flows are equal and that pressure drops created within the 6 heat exchanger are higher on the fresh air channel because of its fluted passageway, thus preventing the flap from opening.
Different mechanisms have been proposed in order to defrost the ventilator, for example, as disclosed in Canadian Patent No. 2,059,195 and Canadian Patent No.
11 2,140,232. According to the latter, two actuators and respective valves or flaps are used to close the exhaust outlet and fresh supply air inlet. Stale air is thereby redirected to return back through the fresh supply air passageway to defrost the stale exhaust air passageway. This is carried out periodically, typically before the passageways totally freeze up. A drawback to this arrangement is the cost and complexity associated with 16 utilizing two actuators each controlling separate valves or flaps.
The former patent suggests that instead of having two actuators, it is possible to prevent the cold supply infiltration inlet by diverting stale air exhaust back through the fresh supply air passages in the heat exchanger. While this does eliminate a valve or flap 21 and an actuator, it does present its own problems. As the actuator and flaps are disposed adjacent the cold supply there is a possibility of their freezing, thereby rendering them inoperable. Furthermore, while the fresh air supply is closed stale air is recirculated.
Other problems inherent with conventional heat recovery ventilators is that, while 26 such ventilators in a continuous operational mode, with both fans operating, to circulate air through the heat exchanger provides a balanced ventilation, during defrost mode, however, the fresh air intake motor shuts off to allow the stale air to warm up the heat exchanger, and such a shut off system can contribute to the depressurization within the dwelling. What is required is a heat recovery ventilator defrost system which introduces 31 warm air in both channels of the heat exchanger to limit the depressurization and increase the efficiency of a defrost system.
2 An object of the present invention is to provide an improved heat recovery ventilator defrost system utilizing a bypass section which supplies warm air in both channels of the heat exchanger to accelerate defrost, continue some ventilation of stale 6 cold air, and recirculate a portion of the warm stale air flow to limit the depressurization effect, so as to maintain the heating capacity of the heat exchanger.
According to another object of the present invention, there is provided an improved heat recovery ventilator defrost system which utilizes a non-motorized bypass 11 section for supplying warm air to both channels of the heat exchanger.
A still further object of the present invention is to provide an improved heat recovery ventilator defrost system which uses two independent air flows for defrosting of the heat exchanger.

A still further object of the present invention involves providing a means for protection against system failures. A malfunction that would have both motors operate continuously in wintertime would eventually produce frost build up in the stale air passageway of the heat recovery element, thus increasing the pressure drop that would in 21 turn open the bypass section to let the warm stale air flow in the fresh air passageway to reheat the heat exchanger.
According to one aspect of the present invention, there is provided a heat
3 1 recovery ventilator comprising a heat exchanger having discrete inlet and exhaust passageways extending therethrough for providing heat transfer and flow between respective fluids flowing along said inlet and said exhaust passageways, said inlet passageway providing fluid communication between an inlet plenum and a supply plenum, said exhaust passageway providing fluid communication between an exhaust 6 plenum and an exhaust discharge plenum; and a bypass section positioned between said inlet plenum and said exhaust plenum, the bypass section being movable between a venting configuration, in which the bypass section is in a closed position for allowing fluid communication between the exhaust plenum and the exhaust discharge plenum, and a defrost configuration, in which the bypass section is in an open position and permits 11 fluid communication between said inlet plenum and said exhaust plenum, in addition to allowing fluid communication between the exhaust plenum and the exhaust discharge plenum.
According to another aspect of the present invention, there is provided a heat 16 recovery ventilator comprising a heat exchanger having discrete inlet and exhaust passageways extending therethrough for providing heat transfer and flow between respective fluids flowing along said inlet and said exhaust passageways, said inlet passageway providing fluid communication between an inlet plenum having an inlet port for admitting supply air into said inlet plenum and a supply plenum having a supply port 21 for discharging supply air, said exhaust passageway providing fluid communication between an exhaust plenum having an exhaust inlet port and an exhaust discharge plenum, said exhaust discharge plenum having an exhaust port for discharging exhaust
4 1 air from said exhaust discharge plenum; and a bypass section positioned between said inlet plenum and said exhaust plenum, the bypass section being movable between a venting configuration, in which the bypass section is in a closed position for allowing fluid communication between the exhaust plenum and the exhaust discharge plenum, and a defrost configuration, in which the bypass section is in an open position and permits 6 fluid communication between said inlet plenum and said exhaust plenum, in addition to allowing fluid communication between the exhaust plenum and the exhaust discharge plenum.
Yet another aspect of the present invention provides for a heat recovery ventilator 11 comprising a heat exchanger having discrete inlet and exhaust passageways extending therethrough for providing heat transfer and flow between respective fluids flowing along said inlet and said exhaust passageways, said inlet passageway providing fluid communication between an inlet plenum having an inlet port for admitting supply air into said inlet plenum and a supply plenum having a supply port for discharging supply air, 16 said exhaust passageway providing fluid communication between an exhaust plenum having an exhaust inlet port and an exhaust discharge plenum, said exhaust discharge plenum having an exhaust port for discharging exhaust air from said exhaust discharge plenum; a supply fan mounted within the inlet plenum for augmenting fluid flow along said inlet passageway; an exhaust fan mounted within one of the exhaust plenum and the 21 exhaust discharge plenum for augmenting fluid flow along the exhaust passageway; and a bypass section positioned between said inlet plenum and said exhaust plenum, the bypass section being movable between a venting configuration, in which the supply fan is turned 1 on and the bypass section assumes a closed position for allowing fluid communication between the exhaust plenum and the exhaust discharge plenum, and a defrost configuration, in which the supply fan is turned off and the bypass section assumes an open position and permits fluid communication between said inlet plenum and said exhaust plenum, in addition to allowing fluid communication between the exhaust 6 plenum and the exhaust discharge plenum.
The advantage of the present invention is that it provides an improved heat recovery ventilator defrost system utilizing a bypass section which supplies warm air in both channels of the heat exchanger to accelerate defrost, continue some ventilation of 11 stale cold air, and recirculate a portion of the warm stale air flow to limit the depressurization effect, so as to maintain the heating capacity of the heat exchanger.
Yet another advantage of the present invention is that it provides an improved heat recovery ventilator defrost system which utilizes a non-motorized bypass section for 16 supplying warm air to both channels of the heat exchanger.
A still further advantage of the present invention is that it provides an improved heat recovery ventilator defrost system which uses two independent air flows for defrosting of the heat exchanger.

A still further advantage of the present invention is that it provides a means for protection against system failures. A malfunction that would have both motors operate 1 continuously in wintertime would eventually produce frost build up in the stale air passageway of the heat recovery element, thus increasing the pressure drop that would in turn open the bypass section to let the warm stale air flow in the fresh air passageway to reheat the heat exchanger.

Figure 1 is a side perspective view, which illustrates the intake of fresh air and exhaust of stale air in a conventional air exchange ventilation system;
Figure 2 is a side perspective view of one embodiment of the present invention, which 11 illustrates the intake of fresh air and exhaust of stale air, and which illustrates the airflow of two independent air flows for defrosting of the heat exchanger; and Figure 3 is a diagram of an interior of a heat recovery ventilator according to the present invention in a ventilation mode;

Figure 4 is a side view which illustrates the intake of fresh air and exhaust of stale air in a conventional air exchange ventilation system;
Figure 5 is a side view which further illustrates the embodiment shown in Figure 3, and 21 which shows an interior of a heat recovery ventilator according to the present invention in a ventilation mode;
Figure 6 is a side view which further illustrates the embodiment shown in Figure 3, and which shows an interior of a heat recovery ventilator according to the present invention in 26 a ventilation mode; and 1 Figure 7 is a side view which further illustrates the embodiment shown in Figure 3, and which shows an interior of a heat recovery ventilator according to the present invention in a ventilation mode.
DESCRIPTION OF THE PREFERRED EMBODIMENT
6 The present invention provides a defrost arrangement for air exchange ventilators which includes a heat exchanger to extract heat from the stale air and transfer it to the incoming fresh air, and which introduces warm air in both channels of the heat exchanger to accelerate defrost, continue some ventilation of stale warm air, and recirculate a portion of the stale air flow at mild temperatures as opposed to the lower temperatures of 11 incoming fresh air. In conventional systems, during the defrost mode the fresh air motor shuts off, and warm stale air is used to defrost the heat exchanger. This air is then totally expelled outdoors which can contributes to the depressurization within the dwelling or building. With reference to Figures 1 and 4, incoming fresh air is admitted into the air exchange system at (2) to flow through an inlet passageway (4), which is then passed 16 through the heat exchanger (6), to flow (8) into an enclosure. Exhaust air to be discharged from the enclosure flows at (10) through the heat exchanger (6) to an outlet passageway (12) and out of the enclosure at (14).
In the present invention, the heat recovery ventilator utilizes a non-motorized 21 bypass section (flap) to introduce warm air to both channels of the heat exchanger, so as to accelerate defrost, continue some ventilation of stale warm air, and recirculate a portion of the stale air flow, so as to warm incoming cold fresh air. In the present invention, because the stale air is under a positive pressure, the air being bypassed is 1 being sucked back into the dwelling, thus reducing the net stale air exhausted to the outdoors. Thus, the present invention provides a highly effective defrost arrangement for air exchange ventilators which operates to provide extreme weather performance, and withstand extreme cold. During normal ventilation, the static pressure created by air moving through the fresh air passages in the heat exchanger creates more of a pressure 6 drop than the strait air passages on the stale air side. Thus, this differential pressure is used to close off the bypass section (flap).
In one embodiment of the present invention and with reference to Figure 2, a heat recovery ventilator 1 utilizes a non-motorized bypass section (flap) 42 to introduce warm 11 air to both channels of the heat exchanger or heat exchanger 6 during defrost, in one air flow marked as S to warm one channel of the heat exchanger 6, and another independent air flow 7, which flows through the bypass section (flap) 42 to warm the other channel of the heat exchanger 6.
16 During defrost, and with further reference to Figures 3, 5, 6 and 7, at the heat exchanger of the heat recovery ventilator 1 is a heat exchanger 6 having an inlet passageway illustrated by arrow 20 and an exhaust passageway illustrated by arrow 36.
To augment air flow along the inlet passageway 20 and exhaust passageway 36, an exhaust fan 54 may be mounted within an exhaust plenum 34, and a supply fan 60 may 21 be mounted in an inlet plenum 24. Of course, providing such fans within the heat recovery ventilator 1 is desirable in order to make the heat recovery ventilator 1 a "stand 1 alone" unit. Preferably, these fans should be of similar capacity and may be arranged, if required, to share a common motor (not shown).
A housing (not shown) defines an exterior of the heat recovery ventilator 1, and it will be appreciated that the actual unit will have a front cover, which is not shown in the 6 Figures so as to show its interior. The inlet passageway 20 and outlet passageway 36 allow heat transfer between respective fluids flowing therealong without allowing co-mingling of the fluids. As is common with air to air heat exchangers, the heat exchanger 6 may comprise a plurality of individual passageways therein (not shown), which allows fluids flowing in the inlet passageway 20 and exhaust passageway 36 and through the 11 heat exchanger 6 a greater surface area with which to enhance heat transfer. The inlet passageway provides fluid communication between the inlet plenum 24 and supply plenum 26. The outlet passageway provides fluid communication between the exhaust plenum 34 and discharge plenum 40. The inlet plenum 24 has an intake port 30 for admitting fresh supply air (outside air) 28 into the inlet plenum 24.

The supply plenum 26 has a supply port 31 for discharging air 29, which has passed through the heat exchanger 6 from the heat recovery ventilator 1 into an enclosure or dwelling. The discharge plenum 40 has an exhaust port 33 for discharging exhaust air 37 from the discharge plenum 40. The exhaust plenum 34 has an exhaust inlet port 35 for 21 admitting warm air 38 from an enclosure or dwelling into the exhaust plenum 34. It will, however, be understood that external fans (not shown) might also be connected to the exhaust inlet port 35 and the intake port 30 to assist in augmenting air flow along the 1 inlet passageway 20 and outlet passageway 36.
A non-motorized bypass section (flap) 42 separates the inlet plenum 24 and the exhaust plenum 34, and, when the bypass section (flap) 42 is opened, provides fluid flow and communication therebetween, in a discharge mode. As noted previously, the heat 6 recovery ventilator utilizes a non-motorized, passive bypass section (flap) 42 to introduce warm air to both channels of the heat exchanger 6, so as to accelerate defrost, continue some ventilation of stale warm air, and recirculate a portion of the stale air flow, so as to warm incoming cold fresh air. In the present invention, because the air is under a negative pressure, the air being bypassed is being sucked back into the dwelling, thus 11 reducing the net stale air exhausted to the outdoors. With further reference to Figure 3, when heat recovery ventilator 1 is in its ventilation mode, warm moist air from a dwelling is replaced with fresh outside air, while, at the same time, recovering the heat from the warm moist air to be expelled and transferring it to the incoming fresh outside air, while at the same time accelerating defrosting of the heat exchanger 6.
Of course, the 16 transfer of heat to the incoming fresh air will cause condensation on the heat exchanger, which will accumulate, thus requiring defrosting of the heat exchanger 6.
As noted above, the air being exhausted (by way of the exhaust fan) through the exhaust plenum 34 is under a negative pressure, so the stale air will still be sucked out, 21 and fresh air drawn in, even when the fresh air supply fan is not on (such as during defrost mode). In the embodiment of the present invention shown in Figure 3, warm exhaust air 38 to be expelled enters the exhaust inlet port 35 and into the exhaust plenum 34. Because the air being exhausted (by way of the exhaust fan) through the exhaust plenum 34 is under a negative pressure, the stale air will still be sucked out through 26 exhaust passageway 36 into discharge plenum 40 (along flow path 77 in Figure 3 and 1 which is also indicated as flow path "B" in Figure 5), but also through the passive non-motorized bypass section (flap) 3 (which move to allow the air flow therethrough under the negative pressure) into inlet plenum 24 (along flow path 79 in Figure 3 and which is also indicated as flow path "A" in Figure 5). Further, because fresh air continues to be drawn into inlet plenum 24, due to the negative pressure, the warm stale air which has 6 passed through the bypass section (flap) 42 into inlet plenum 24 is then drawn through the heat exchanger 6 along the inlet passageway 20 into supply plenum 26, and out through supply port 31 into the enclosure or dwelling. With reference to Figures 3,5,6 and 7, it can be seen that two independent air flows are introduced in both channels of the heat exchanger 6, so as to accelerate defrost, continue some ventilation of stale warm air, 11 and recirculate a portion of the stale air flow at mild temperatures as opposed to the lower temperatures of incoming fresh air. During normal ventilation (that being, when the fresh air supply motor is engaged after the defrost mode), the static pressure then created by air moving through the fresh air passages in the heat exchanger creates more of a pressure drop than the strait air passages on the stale air side. Thus, this differential 16 pressure is used to then close off the bypass section (flap).
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled 21 in the art are intended to be included within the scope of the following claims.

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A heat recovery ventilator comprising:

a heat exchanger having discrete inlet and exhaust passageways extending therethrough for providing heat transfer and flow between respective fluids flowing along said inlet and said exhaust passageways, said inlet passageway providing fluid communication between an inlet plenum and a supply plenum, said exhaust passageway providing fluid communication between an exhaust plenum and an exhaust discharge plenum; and a bypass section positioned between said inlet plenum and said exhaust plenum, the bypass section being movable between a venting configuration, in which the bypass section is in a closed position for allowing fluid communication between the exhaust plenum and the exhaust discharge plenum, and a defrost configuration, in which the bypass section is in an open position and permits fluid communication between said inlet plenum and said exhaust plenum, in addition to allowing fluid communication between the exhaust plenum and the exhaust discharge plenum.
2. The heat recovery ventilator of claim 1, wherein the inlet plenum further comprises an inlet port for admitting supply air into said inlet plenum.
3. The heat recovery ventilator of claim 1 or 2, wherein the supply plenum further comprises a supply port for discharging supply air from the supply plenum.
4. The heat recovery ventilator of claim 1 or 2, wherein the exhaust plenum further comprises an exhaust inlet port for admitting exhaust air into the exhaust plenum.
5. The heat recovery ventilator of claim 1 or 2, wherein the exhaust discharge plenum further comprises an exhaust port for discharging exhaust air from the exhaust discharge plenum.
6. A heat recovery ventilator comprising a heat exchanger having discrete inlet and exhaust passageways extending therethrough for providing heat transfer and flow between respective fluids flowing along said inlet and said exhaust passageways, said inlet passageway providing fluid communication between an inlet plenum having an inlet port for admitting supply air into said inlet plenum and a supply plenum having a supply port for discharging supply air, said exhaust passageway providing fluid communication between an exhaust plenum having an exhaust inlet port and an exhaust discharge plenum, said exhaust discharge plenum having an exhaust port for discharging exhaust air from said exhaust discharge plenum; and a bypass section positioned between said inlet plenum and said exhaust plenum, the bypass section being movable between a venting configuration, in which the bypass section is in a closed position for allowing fluid communication between the exhaust plenum and the exhaust discharge plenum, and a defrost configuration, in which the bypass section is in an open position and permits fluid communication between said inlet plenum and said exhaust plenum, in addition to allowing fluid communication between the exhaust plenum and the exhaust discharge plenum.
7. A heat recovery ventilator as claimed in any one of claims 1 to 6, wherein any of the said inlet passageway and exhaust passageway includes a plurality of individual adjacent passageways.
8. A heat recovery ventilator as claimed in any one of claims 1 to 7, wherein the supply inlet plenum, the supply discharge plenum, the exhaust inlet plenum and the exhaust discharge plenum are at least partially defined by a housing containing the heat exchanger.
9. A heat recovery ventilator as claimed in any one of claims 1 to 8, wherein fluid flow along the exhaust passageway is augmented by an exhaust fan mounted within one of the exhaust plenum and the exhaust discharge plenum.
10. A heat recovery ventilator as claimed in any one of claims 1 to 9, wherein fluid flow along said inlet passageway is augmented by a supply fan mounted within the inlet plenum.
11. A heat recovery ventilator as claimed in claim 9 or 10, wherein the exhaust fan and the supply fan are of similar capacity.
12. A heat recovery ventilator as claimed in claim 11, wherein the exhaust fan and the supply fan share a common fan motor.
13. A heat recovery ventilator comprising:
a heat exchanger having discrete inlet and exhaust passageways extending therethrough for providing heat transfer and flow between respective fluids flowing along said inlet and said exhaust passageways, said inlet passageway providing fluid communication between an inlet plenum having an inlet port for admitting supply air into said inlet plenum and a supply plenum having a supply port for discharging supply air, said exhaust passageway providing fluid communication between an exhaust plenum having an exhaust inlet port and an exhaust discharge plenum, said exhaust discharge plenum having an exhaust port for discharging exhaust air from said exhaust discharge plenum;
a supply fan mounted within the inlet plenum for augmenting fluid flow along said inlet passageway;
an exhaust fan mounted within one of the exhaust plenum and the exhaust discharge plenum for augmenting fluid flow along the exhaust passageway; and a bypass section positioned between said inlet plenum and said exhaust plenum, the bypass section being movable between a venting configuration, in which the supply fan is turned on and the bypass section assumes a closed position for allowing fluid communication between the exhaust plenum and the exhaust discharge plenum, and a defrost configuration, in which the supply fan is turned off and the bypass section assumes an open position and permits fluid communication between said inlet plenum and said exhaust plenum, in addition to allowing fluid communication between the exhaust plenum and the exhaust discharge plenum.
14. The heat recovery ventilator as claimed in claim 13, wherein, when the supply fan is turned off during the defrost configuration, the exhaust air being exhausted through the exhaust plenum is under a positive pressure, and, as a result of the positive pressure, the exhaust air continues to be drawn out while supply air continues to be drawn in to the inlet plenum.
15. The heat recovery ventilator as claimed in claim 14, wherein, when the supply fan is turned on during the venting configuration, static pressure is created by supply air moving through the inlet passageway in the heat exchanger, and the static pressure creates a greater pressure drop than static pressure created by exhaust air moving through the exhaust passageway in the heat exchanger, which moves the bypass section to assume the closed position.
16. The heat recovery ventilator as claimed in claim 14, wherein the bypass section is a passive, non-motorized damper.
CA002509571A 2005-06-09 2005-06-09 Pressure sensitive bypass defrost system Abandoned CA2509571A1 (en)

Priority Applications (2)

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CA002509571A CA2509571A1 (en) 2005-06-09 2005-06-09 Pressure sensitive bypass defrost system
US11/423,011 US20070084586A1 (en) 2005-06-09 2006-06-08 Pressure Sensitive Bypass Defrost System

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FR3013823A1 (en) * 2013-11-28 2015-05-29 Elyt 3 DOUBLE FLOW AIR / AIR EXCHANGER, AIR TREATMENT PLANT AND METHOD FOR CLEANING SUCH EXCHANGER
WO2015079046A1 (en) * 2013-11-28 2015-06-04 Elyt 3 Dual-flow air/air exchanger, apparatus for processing air and method for protecting such an exchanger against ice and for cleaning same
JP2016540183A (en) * 2013-11-28 2016-12-22 エリート・トロワ Dual-flow air / air exchanger, apparatus for treating air, and method for protecting such an exchanger from ice and purifying it
US10408479B2 (en) 2013-11-28 2019-09-10 F2A-Fabrication Aeraulique Et Acoustique Dual-flow air/air exchanger, apparatus for processing air and method for protecting such an exchanger against ice and for cleaning same
CN106765993A (en) * 2017-01-19 2017-05-31 浙江森风环境设备科技有限公司 Fresh air interchanger defroster

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