American Aldes HRVERV Installation User Manual

							POINTS TO CONSIDER WHEN LOCATING THE HRV/ERV UNIT
The Heat or Energy Recovery Ventilator (HRV/ERV) must be installed where temperatures will remain above freezing (32°F). The 
unit must be installed where it is easily accessible for maintenance and filter changes. The unit should be relatively close to an 
exterior wall to minimize the length of insulated duct to the exterior vent hoods. The outdoor duct connections must be insulated 
with a complete exterior vapor jacket to prevent indoor moisture from condensing on the inner duct, which would water-log 
the insulation layer. The duct connections to the heat exchanger and the exterior vent hoods must be designed to maintain this 
vapor jacket over the insulation. The fresh air intake must be located approximately six feet or more from any exhaust device, 
including the discharge from the HRV/ERV. It should not be installed where noxious gases from outdoor sources are likely to be 
present, such as the exhaust of an automobile in a driveway.
DUCTING TO THE INTERIOR SPACES - EXHAUST AIR CIRCUIT
American Aldes recommends using the HRV/ERV to ventilate bathrooms and non-cooking, low exhaust areas in kitchens, pantries 
and laundry rooms, provided that the duct runs can be accomplished within the recommended distance and availability of wall 
and ceiling/floor cavities or special chases. If this is possible, the HRV/ERV can do double duty as the local exhaust of these spaces 
and as general indoor air quality throughout the dwelling. In addition, quiet ventilation of these areas is assured by the remote 
mounting of the ventilator.
FRESH OUTDOOR AIR CIRCUIT
Fresh supply air should be ducted to the bedrooms and main living areas (bedrooms with an attached bath that is being exhausted 
do not require a dedicated supply, as fresh air will be drawn through the bedroom to the bathroom).
AMERICAN ALDES DOES NOT RECOMMEND CONNECTING TO FORCED-AIR DUCTING. Contrary to the recommendations of most 
manufacturers of heat and energy recovery ventilators, American Aldes strongly discourages drawing exhaust air from the return 
HVAC ducting and supplying the fresh air directly into the HVAC duct system. In the case of both heating and cooling systems, 
connecting to the ducting can result in severe imbalance of supply and exhaust airflows as the HRV/ERV operates on low to high 
speeds, as well as the variable speed operation of modern furnaces and air conditioners. It is virtually impossible to assure the 
design airflows will remain in balance when the two systems are operated at varying blower speeds, and the result is a large 
variation of static pressure in the HVAC ducting system.
The exhaust fan in the HRV/ERV is working against the negative pressure in the return plenum. If the return plenum pressure is 
sufficiently high with the HVAC blower running, it can reduce or even stall the exhaust airflow. At the same time, if the HRV/ERV 
supplies air to the return plenum, the supply blower has the assistance of the HVAC blower to supply excess fresh air whenever 
the HVAC system is operating. This situation makes it difficult to assure the HRV/ERV will remain in balance.
If the HRV/ERV is set up to operate only with the HVAC system, then mechanical ventilation is not provided when most needed – 
in milder weather but when windows remain closed. Ventilation is likely to be excessive in severe weather when the air handler 
operates more frequently.
POINTS TO CONSIDER REGARDING CONTINUOUS OPERATION OF THE HVAC OR FURNACE
NOTE:  American Aldes uses the term furnace to refer to a forced air heating system and HVAC to refer to a forced air heating and 
cooling system. In climates where no air conditioning is required, it is possible to exhaust from and supply to the furnace return and 
operate the furnace blower continuously (although there may be a significant electrical penalty for the continuous operation of the 
furnace blower 24 hours per day).
Continuous operation of the HVAC blower is strongly discouraged in climates with warm summers and high humidity, whether or 
not fresh air is introduced to the system. If the blower continues to run for extended times after the cooling thermostat is satisfied, 
the water remaining on the coil and in the drain pan re-evaporates. During this time, the air continues to be cooled by the cold AC 
coil and by the evaporation of water, so the space temperature continues to decrease, while the relative humidity increases. On the 
next cooling cycle, this humidity has to be condensed again, so any efficiency gain in evaporating this water is offset by the next 
cycle and by the loss of comfort at higher relative humidity.
More importantly, in the case of air conditioning, American Aldes does not recommend ducting the supply air from the HRV to the 
Considerations for Locating, Installing, and 
Ducting Heat & Energy Recovery Ventilators
APPLICATION 
GUIDE 
						

							HRV/ERV Considerations
2
ducting of the HVAC. (During summer months, the outdoor 
humidity supplied through the HRV may cause condensation 
on interior surfaces of the HVAC equipment and the supply 
plenum and ducting. These surfaces will be around 60°F, and 
outdoor air dew points in the summer in much of the United 
States are well above this temperature. These are the very 
conditions that promote mold growth. It would be ironic if 
the very system tasked to provide good indoor air quality by 
means of ventilation were to be the means of promoting mold 
growth, by lack of attention to basic psychrometric principles.
THE SOLUTION RECOMMENDED BY AMERICAN ALDES
The best solution is a totally independent ducted system 
for the HRV/ERV, with exhaust from the bathrooms, kitchen 
and laundry/utility rooms, and fresh air ducted to bedrooms. 
(Bedrooms with attached baths connected to the HRV/ERV 
exhaust ducting do not need direct supply, as the exhaust of 
the bath will draw air from the main living areas and hallways 
through the bedroom to the bathroom exhaust grille.)
An alternate solution permits fresh air from the HRV/ERV 
to be supplied to a main living area, where it can be drawn 
into the return ducting and distributed by the HVAC system 
throughout the house. A cycle timer can operate the HVAC 
blower periodically to assure the distribution of fresh air. A 
cycle timer permits the use of the HVAC system to distribute 
the fresh air without the need for a dedicated supply duct 
system. Rather than making a hard connection of the supply 
air to the return duct of the HVAC system, American Aldes 
recommends supplying air through a supply diffuser close 
to a major return grille for the HVAC. This way the fresh air 
is dispersed in the room, avoiding a high concentration of 
outdoor humidity in the cold ducting.
To assure thorough mixing of fresh air throughout the home, 
use a cycle timer to periodically turn on the HVAC blower a 
few minutes every hour. This device wires in parallel with 
the thermostat to periodically operate the blower. It avoids 
redundant fan operation by starting a timed off-cycle at the 
end of blower operation for a heating, cooling or previous 
ventilation cycle. Then it turns on for a few minutes, as set by 
the installer or occupant. This approach reduces the electrical 
cost of constant fan operation and reduces draft during the 
winter, all while assuring good mixing of fresh air throughout 
the home. (If the occupant intends to operate the central fan 
continuously, as for an electronic air cleaner, and in those 
cases where the issues discussed above regarding humidity, 
comfort and potential of mold growth in the ducting do not 
apply, then the use of a cycle timer is not necessary.)
American ALDES Ventilation Corporation  •  4521 19th Street Court East, Suite 104  •  Bradenton, FL 34203 – USA
941.351.3441  •  800.255.7749  •  941.351.3442 (fax)  •  [email protected]  •  www.aldes.us
© 2013 American ALDES Ventilation Corporation.  Reproduction or distribution, in whole or in part, of this document, in any form or by any means, without the express written consent of American ALDES Ventilation Corporation, is strictly prohibited. The information contained within this document is subject to change without prior written notice.
hrv-erv  considerations_application  guide_1113   
The most desirable configuration. 
Highly recommended to get the 
best results in all climate types.
A hybrid approach that allows 
the system to be an effective 
exhaust fan, while taking 
advantage of the central H/AC 
duct system to distribute fresh 
air. Maintaining unit balance is 
often challenging.
The least desirable solution 
because it is difficult to 
assure balanced airflow 
and can cause moisture 
problems in duct during 
warm, humid seasons. 
Requires knowledgeable 
installer.
Fully Ducted System
Dedicated Exhaust Points with Distribution of Fresh 
Supply Air through the Central H/AC System
Exhaust from H/AC Return and Distribution of Fresh Air 
through H/AC System