Integrated heat and energy recovery ventilator system
A heat recovery ventilator (HRV) and/or energy recovery ventilator (ERV) that integrates with a residential capacity air handling unit (AHU) is embodied in a small footprint HRV or ERV unit that connects directly to the return side of an AHU and to outdoor air inlet and exhaust ducts. The ventilator includes a control system incorporating a processor and sensors that control the operation of the system to provide desired ventilation flow rates under varying conditions.
1. A heat recovery ventilator, comprising:
a case adapted to be mounted directly to a return side of an air handling unit of a residential HVAC system, said case having a front face panel, a left side panel, a rear face panel, a right side panel, a top cover panel and a bottom cover panel, and having:
a first case opening in the left side panel or the right side panel, the first case opening connecting to a mixing plenum in a portion of the case and providing a mixing plenum air inlet for receiving a return air from a conditioned space;
a second case opening in the same side panel of the first case opening, the second case opening connecting to an extract air flow path and providing an extract air inlet for receiving an extract air portion of the return air from the conditioned space;
a third case opening in the top cover panel or the bottom cover panel, the third case opening connecting to the mixing plenum and providing a mixing plenum air outlet for releasing air from the mixing plenum directly to the air handling unit;
a fourth case opening in the rear face panel or the front face panel, the fourth case opening connecting to an outdoor air flow path and providing an outdoor air inlet for receiving an outdoor air;
a fifth case opening in the rear face panel or the front face panel, the fifth case opening connecting to an exhaust air flow path and providing an exhaust air outlet for releasing an exhaust air;
the case containing:
an air-to-air exchanger;
the extract air flow path connecting the extract air inlet to the air to air exchanger;
the outdoor air flow path connecting the outdoor air inlet to the air to air exchanger whereby the outdoor air received in the air to air exchanger is tempered by the extract air to provide a tempered outdoor air;
a tempered outdoor air flow path connecting the air to air exchanger to the mixing plenum whereby the tempered outdoor air is released to the mixing plenum and mixed with the return air from the conditioned space in the mixing plenum; wherein the mixing plenum does not contain the air-to-air exchanger or any other heat exchanger or heat recovery core;
the exhaust air flow path connecting the air to air exchanger to the exhaust air outlet;
whereby the extract air is passed through the air to air exchanger and becomes the exhaust air; and
whereby the exhaust air flows through the exhaust air flow path to the exhaust air outlet;
a variable speed outdoor air fan provided in the outdoor air flow path or the tempered outdoor air flow path for controlling a quantity of outdoor air received to the air-to-air exchanger; and
a variable speed exhaust fan provided in the exhaust air flow path for controlling a quantity of extract air received to the air-to-air exchanger.
2. The heat recovery ventilator of claim 1 , further comprising an outdoor air intake damper provided in the outdoor air flow path for controlling a quantity of outdoor air received to the air-to-air exchanger.
3. The heat recovery ventilator of claim 2 , further comprising a control system which activates the outdoor air intake damper to close the damper when negative pressure in the mixing plenum draws in more outdoor air through the air-to-air exchanger than desired or when closure of the outdoor air flow path is desired.
4. The heat recovery ventilator of claim 1 , further comprising a control system, wherein the control system comprises:
means for determining a volumetric flow rate of air through the outdoor air inlet; and
means responsive to the means for determining the volumetric flow rate of air through the outdoor air inlet to control a speed of the variable speed outdoor air fan.
5. The heat recovery ventilator of claim 2 , further comprising a control system, wherein the control system comprises:
means for controlling the outdoor air intake damper and/or outdoor air fan.
6. The heat recovery ventilator of claim 1 , further comprising a control system to maintain desired ventilation flow rates under varying conditions and heating/cooling operation of the air handling unit, comprising:
means for receiving a user directed outdoor air volumetric flow target;
means for comparing a determined volumetric flow rate to the user directed outdoor air volumetric flow target; and
means of controlling one or more of the fans whereby the difference between the determined volumetric flow rate and the user directed outdoor air volumetric flow target is reduced to less than 5 cfm over the course of 1 minute.
7. The heat recovery ventilator of claim 1 , wherein the variable speed outdoor air fan is positioned adjacent to an outer surface of the air to air exchanger in the tempered outdoor air flow path.
8. The heat recovery ventilator of claim 1 , wherein the variable speed exhaust fan is positioned adjacent to an outer surface of the air to air exchanger in the exhaust air flow path.
9. An energy recovery ventilator, comprising:
a case adapted to be mounted directly to a return side of an air handling unit of a residential HVAC system, said case having a front face panel, a left side panel, a rear face panel, a right side panel, a top cover panel and a bottom cover panel, and having:
a first case opening in the left side panel or the right side panel, the first case opening connecting to a mixing plenum in a portion of the case and providing a mixing plenum air inlet for receiving a return air from a conditioned space;
a second case opening in the same side panel of the first case opening, the second case opening connecting to an extract air flow path and providing an extract air inlet for receiving an extract air portion of the return air from the conditioned space;
a third case opening in the top cover panel of the bottom cover panel, the third case opening connecting to the mixing plenum and providing a mixing plenum air outlet for releasing air from the mixing plenum directly to the air handling unit;
a fourth case opening in the rear face panel or the front face panel, the fourth case opening connecting to an outdoor air flow path and providing an outdoor air inlet for receiving an outdoor air;
a fifth case opening in the rear face panel or the front face panel, the fifth case opening connecting to an exhaust air flow path and providing an exhaust air outlet for releasing an exhaust air;
the case containing:
an air-to-air exchanger;
the extract air flow path connecting the extract air inlet to the air to air exchanger;
the outdoor air flow path connecting the outdoor air inlet to the air to air exchanger whereby the outdoor air received in the air to air exchanger is tempered by the extract air to provide a tempered outdoor air;
a tempered outdoor air flow path connecting the air to air exchanger to the mixing plenum whereby the tempered outdoor air is released to the mixing plenum and mixed with the return air from the conditioned space in the mixing plenum; wherein the mixing plenum does not contain the air-to-air exchanger or any other heat exchanger or heat recovery core;
the exhaust air flow path connecting the air to air exchanger to the exhaust air outlet;
whereby the extract air is passed through the air to air exchanger and becomes the exhaust air; and
whereby the exhaust air flows through the exhaust air flow path to the exhaust air outlet;
a variable speed outdoor air fan provided in the outdoor air flow path or the tempered outdoor air flow path for controlling a quantity of outdoor air received to the air-to-air exchanger; and
a variable speed exhaust fan provided in the exhaust air flow path for controlling a quantity of extract air received to the air-to-air exchanger.
10. The energy recovery ventilator of claim 9 , further comprising an outdoor air intake damper provided in the outdoor air flow path for controlling a quantity of outdoor air received to the air-to-air exchanger.
11. The energy recovery ventilator of claim 10 , further comprising a control system which activates the outdoor air intake damper to close the damper when negative pressure in the mixing plenum draws in more outdoor air through the air-to-air exchanger than desired or when closure of the outdoor air flow path is desired.
12. The energy recovery ventilator of claim 9 , further comprising a control system, wherein the control system comprises:
means for determining a volumetric flow rate of air through the outdoor air inlet; and
means responsive to the means for determining the volumetric flow rate of air through the outdoor air inlet to control a speed of the variable speed outdoor air fan.
13. The energy recovery ventilator of claim 10 , further comprising a control system, wherein the control system comprises:
means for controlling the outdoor air intake damper and/or outdoor air fan.
14. The energy recovery ventilator of claim 9 , further comprising a control system to maintain desired ventilation flow rates under varying conditions and heating/cooling operation of the air handling unit, comprising:
means for receiving a user directed outdoor air volumetric flow target;
means for comparing a determined volumetric flow rate to the user directed outdoor air volumetric flow target; and
means of controlling one or more of the fans whereby the difference between the determined volumetric flow rate and the user directed outdoor air volumetric flow target is reduced to less than 5 cfm over the course of 1 minute.
15. The energy recovery ventilator of claim 9 , wherein the variable speed outdoor air fan is positioned adjacent to an outer surface of the air to air exchanger in the tempered outdoor air flow path.
16. The energy recovery ventilator of claim 9 , wherein the variable speed exhaust fan is positioned adjacent to an outer surface of the air to air exchanger in the exhaust air flow path.
17. The heat recovery ventilator of claim 1 , wherein the third case opening is provided in the top cover panel and comprises a rectangular opening adapted to mount directly to the air handling unit so that air can be passed directly from the plenum of the HRV/ERV to the plenum of the air handling unit of the HVAC system.
18. The heat recovery ventilator of claim 17 , wherein the first case opening and second case opening are provided in the left side panel, and the fourth case opening and fifth case opening are provided in the rear face panel.
19. The energy recovery ventilator of claim 9 , wherein the third case opening is provided in the top cover panel and comprises a rectangular opening adapted to mount directly to the air handling unit so that air can be passed directly from the plenum of the HRV/ERV to the plenum of the air handling unit of the HVAC system.
20. The heat recovery ventilator of claim 19 , wherein the first case opening and second case opening are provided in the left side panel, and the fourth case opening and fifth case opening are provided in the rear face panel.