HRV

Common Questions about Heat and Energy Recovery Ventilators

905 403 9914

For the past two decades there has been mounting evidence that dependence on the natural exchange of air between the indoors and outdoors through air infiltration and exfiltration may not be satisfactory for good moisture control and indoor air quality. It also has become increasingly obvious that traditional ventilation methods, like opening a window or use of a common bath fan, are not providing adequate ventilation. A properly designed and installed ventilation system is the key to positive moisture control and will help ensure a healthy indoor environment for the occupant.

This paper discusses selecting and maintaining heat recovery ventilators, HRV s and energy recovery ventilators ERV s. These mechanical ventilation systems use fans to maintain a low-velocity flow of fresh outdoor air into the house (incoming air stream) while exhausting out an equal amount of stale indoor air (exhaust air stream). Fresh air is supplied to all levels of the house while stale air is removed from areas with high levels of pollutants and moisture .

Two options for fresh air distribution with a mechanical ventilation system.

1. If connected to a forced air heating/cooling system, intermittent operation of a fan is required for distribution.
2. Primarily for use in homes without a forced air heating or cooling system.
Residential mechanical ventilation systems are used to bring fresh air into and remove stale air from our homes. Two common types are exhaust-only systems and balanced systems. The exhaust-only system has a fan to provide exhaust air; the supply air is not fan powered. The balanced system uses a fan-powered exhaust airflow that is designed to equal the fan-powered supply airflow. The balanced systems may or may not have heat or energy recovery. Those with heat or energy recovery are commonly called an HRV or ERV. An HRV transfers heat while an ERV usually transfers heat and moisture.

The most common HRV/ERVs are duct-connected house units. Other types of HRV/ERVs are wall or window room units. These are more often found in multifamily dwellings than in single family dwellings. The duct-connected units are more effective because they provide for a better distribution/pickup of air. The fan component of the duct-connected system is commonly installed in the utility or furnace room. It should be easily accessible for regular cleaning, air filter replacement, and servicing.

Frequently Asked Questions about HRV and ERV systems. If you require more in formation call our office to speak to one of our installers. Service in Mississauga, Etobicoke, Oakville Burlington GTA Tornto Brampton Lorne Park Streetsville Hamilton Milton brampton.


Who needs an HRV or ERV ?


Every home (new and old) needs ventilation to bring in fresh air, to remove stale air, and provide moisture control. Effective , 1999, new homes constructed will be required to have a mechanical ventilation system to supply outdoor air for the people inside the home. An HRV, ERV is one mechanical ventilation system that offers convenience, comfort and building durability. In new construction, the connections should be roughed in if, for budget reasons, you do not install the HRV/ERV during construction.

Where do I go to buy an HRV/ERV?


A good mechanical contractor is the key to success. If you are building a new house or remodeling, ask your building contractor about the mechanical ventilation options or check the yellow pages for heating and cooling contractors. A contractor experienced in ventilation should be able overcome any obstacles related to the installation. This would include balancing the system and verifying flow to all pickup points and insuring proper application, i.e., sizing, location of inlets and outlets, and zone control.
We install in Mississauga, Etobicoke, Oakville Burlington GTA Tornto Brampton Lorne Park Streetsville Hamilton Milton brampton.

How much does it cost to install an HRV/ERV?


Costs can vary a lot depending on the type and complexity of the installation, as well as on the size and features of the HRV/ERV. For new construction, the costs would normally run from $1,000 to $2,500. It will generally cost more for a retrofit, due to the difficulty of running ductwork to the source points. Volume (or non-source point) ventilation systems can be installed at a lower cost, but may not be as effective and will require the furnace fan to run continuously.

General Design Considerations
locate the fresh air intake away from driveways and laundry and furnace vents.


install a supply inlet (dedicated inlet or heating register, if connected to forced air) for each bedroom and one for each common area. This is not possible on homes that are finnished.


install a return outlet in each high moisture area such as the kitchen, utility room and bathroom.


return outlets (pick up points) should be within one foot of ceiling and 10 feet away from an oven or cooktop, as vaporized grease could clog the energy recovery core.


keep duct runs as short and straight as possible.


use smooth, round ductwork when possible.


insulate intake/exhaust and any ventilation ducts in unheated spaces and seal all joints.


install a drain to catch any condensate, if required.



Will operating costs increase my electric, heating or cooling bill ?


An HRV/ERV requires service and electricity to run the fan but it provides an opportunity for heat recovery. All homes need ventilation air that must be heated in winter and may be cooled and dehumidified in summer. 1 calculated the cost for 80 CFM of continuous balanced ventilation in several Ontario cities with and without heat recovery. A typical annual cost of 80 CFM of continuous ventilation was calculated at $170 with heat recovery and $280 without heat recovery. Of these amounts, approximately $70 is the cost of the electricity to run the 60 W fan).2 Systems requiring the furnace fan to run continuously will have additional costs for operation. Continuous operation of a typical furnace fan for heating or cooling and circulation would range from $0.40 to $1.00 per day.

How does the heat and moisture transfer of an HRV/ERV work?


The incoming fresh air is tempered with a heat or energy recovery core. Heat is exchanged through a core that is frequently made of multiple plates of aluminum or plastic. Water vapor is transferred with a rotating wheel with desiccant material or permeable plates.

Models with heat recovery only transfer heat from the exhaust air stream to the incoming air stream in the heating season and from the incoming air stream to the exhaust air stream in the air conditioning season. Models with heat recovery and moisture recovery transfer heat and moisture from the exhaust airstream to the incoming air stream during the heating season, and transfer heat and water vapor from the incoming air stream to the exhaust air stream during the air conditioning season.

What options and features are available?


Heat recovery with and without moisture transfer control.


Defrost control or preheater system to prevent ice buildup on the recovery module (should be a standard in cold Ontario climates)


single or multiple speed controls (standard on many HRV units.

Pollutant sensor controls (central control with high speed override)


High efficiency air filter on incoming air discuss these options with your mechanical contractor.

How can I compare the performance of different HRV and erv models?


Systems are tested and rated for performance. An independent laboratory such as the Home Ventilation Institute (HVI) should certify tests and ratings. You can compare these performance ratings for:

airflow capacity in cubic feet per minute (CFM)


recovery efficiency of the energy recovery core (heat and/or moisture) in percent sound (noise) level in sones
You can also compare the warranty coverage on installation and parts such as fans, cores, and controls.

What size HRV/ERV do I need?


New homes must comply with the Energy Code. The mechanical ventilation requirement is for airflow and does not require energy recovery. It is based on the number of bedrooms with a minimum airflow of 15 CFM/bedroom + 15 CFM and a total ventilation capacity equal to 0.05 CFM/square foot. Additional ventilation may be needed for special needs such as crafts/hobbies and excessive moisture generated by the occupants or by foundation moisture.

Do I still use a bath fan?


It depends on HRV/ERV duct design, bathroom airflow requirement, and manufacturer’s guidelines.

Do I still use a kitchen exhaust fan? What if I have a “high CFM” fan?


A kitchen exhaust fan is still needed to remove grease and combustion gases. High capacity kitchen exhaust systems (downdraft or range hood with an airflow of greater than 250 CFM) present problems with natural draft combustion appliances and separate makeup air will be needed.

In the summer do I need to use a dehumidifier or air conditioner with an HRV/ERV?


If your unit exchanges moisture, you may not need a dehumidifier. While an HRV/ERV will reduce the cooling load added by the ventilation, it will not eliminate the need for an air conditioner.

In winter can my house get too dry?


If it gets too dry you may need to use a humidifier or temporarily reduce the airflow. Dryness is more likely to happen if the unit exchanges heat but not moisture. You may wish to discuss this with your contractor.

What will I need to do to maintain a system?

Check the owner’s manual. Typically maintenance can be done by the homeowner and includes the following:

clean or replace air filters every 1-3 months.


clean or unblock outside hoods and screens every 13 months


clean the energy recovery core every 6 months


clean condensate drain and pans every 6 months.




The homeowner should also service (oil if needed) and clean fans every 3-6 months, and annually clean grills and inspect ductwork for any leaks or obstructions. In addition, a professional should annually check the system and verify that the system is properly balanced.

We hope this has helped in your decision making for an installation of an HRV and ERV system.If you are still in need of more information on these systems, and need a reputable contractor for installation please call us. 905 403 9914

in Mississauga, Etobicoke, Oakville Burlington GTA Tornto Brampton Lorne Park Streetsville Hamilton Milton brampton.