Does my Heat Recovery Ventilator (HRV) have a problem?

Does my Heat Recovery Ventilator (HRV) have a problem? Do you have condensation in your windows?

No, your HRV is not the problem.
An HRV is an effective, energy-efficient and healthy method of managing moisture in your home in the winter, but your HRV does not remove condensation from your windows, it removes excess moisture in the air.

If condensation forms in your windows, it is because the temperature of the surface of the window is lower than the dew point of the surrounding air. There may be several reasons why the window temperature is below the dew point of the air such as poor window quality or too high a dew point.

The condensation in your windows is the same as the condensation that forms on a cold beverage can on a hot, humid summer day. The surface temperature of the can is lower than the dew point of the air outside.

The dew point of the air depends on the amount of water vapour in the air. The higher the relative humidity, the higher the dew point and the more condensation will occur at high temperatures. For example, air at 21°C and 40% relative humidity has a dew point of 8°C.

All surfaces with a temperature of 8°C or less, such as a window, will become covered by a layer of water droplets.

To eliminate condensation in windows, there are two solutions.

  • Lower the dew point of the surrounding air, or
  • Increase the temperature of the window surface

To lower the dew point

Your HRV is the perfect appliance for lowering the dew point of the air when it is cold outside.  Your HRV will evacuate moist, stale air from your home and replace it with fresh, dry air from outside, lowering the dew point. Why is the air outside dryer? Because cold air holds less water vapour than warm air. When cold air is heated, first through the HRV and then through the home’s heating system, the relative humidity drops.

There are other technologies that can also lower the dew point of your home, for example, a dehumidifier. However, a dehumidifier does not supply any fresh, filtered air.

Increase the temperature of the window surface

The only other possible solution to eliminate condensation in the windows is to increase the temperature of the inner surface of your windows.

Window panes are exposed to very large temperature differentials in the winter. Some windows are better than others at preventing heat loss through transmission. For example a single pane will have almost the same temperature on the inside surface as the outside surface, whereas triple pane windows with air gaps will provide more insulation and significantly reduce heat loss, meaning the inside surface temperature will be closer to the room temperature.

The most effective method for increasing the temperature of the inner window surface is to promote air flow across it. Window treatments, such as curtains or blinds, create “microclimates” near the window and lower the surface temperature, which helps to form condensation.

To promote air circulation near windows, you can:

  • Open the curtains and raise the blinds
  • Use a fan to blow air toward the windows
  • Place a heat source under the window

If your windows are very old and need to be replaced, energy efficient windows (such as triple-pane) will also help ensure the interior surface temperature of the window is higher.  Regardless of the quality of the window, if a “microclimate” is created on the window surface due to a lack of air movement, there could still be some condensation, depending on the outdoor temperature and the indoor dew point.

New version of Selector software is now available!

Selector saves you a lot of time when choosing the right commercial HRV/ERV.

Just select your airflow requirements, design conditions and other criteria, and Selector will propose one or more product models that meet your needs. Then you can generate a submittal PDF with all the project details for quotes and approvals.

The new version now includes all our new Light Commercial HRVs and ERVs, new coil calculations, and many bug fixes.

If you are already using Selector on your Windows device, all you need to do is start it and click on the “Check for updates” button on the title screen.

If you do not already have a copy, please download the installer. Please note that it is an executable file (.exe) and is only compatible with the Windows operating system.

Once the software is installed, start the Selector and fill in your contact information. Enter your e-mail and click the button marked “get registration key by e-mail”. Do not close the program.

Check your e-mail to find the key. Return to Selector and enter the registration key. Click “Key Validation” to activate your copy of the software.

Are Bathroom Fans Obsolete?

The residential ventilation strategy of using an HRV and ZRTs to ventilate bathrooms, instead of using individual bathroom fans, is more cost effective for the builder and for the home owner. Not only is the initial cost of the equipment and installation less expensive: the operating costs are lower as well.
Rather than installing energy-wasting bathroom fans that require individual ducting, it is more advantageous to install zoned exhaust terminals that direct the ventilation capacity of the HRV to the right place at the right time, while recovering most of the heat in the exhaust air.
And there are many other advantages to our approach:

  • Tighter building envelope and more attractive home exterior (fewer penetrations)
  • More balanced ventilation, avoiding negative pressure
  • Quieter operation
  • Avoids user error of leaving the fans on for extended periods

Please check out our new video and go to the Aldes Professional’s Zone (or contact your sales representative) for a copy of our White Paper that shows in detail how Aldes HRVs with ZRTs are winning combination.

Aldes Canada is now a member of the HRAI

Founded in 1968, the Heating, Refrigeration and Air Conditioning Institute of Canada is the national trade association of manufacturers, wholesalers and contractors in the Canadian HVACR industry. Aldes Canada’ membership in this important organization comes as we continue to significantly expand our reach across Canada. Providing fresh healthy air to the occupants of homes and commercial buildings is what we do best, and more and more engineers are specifying Aldes HRVs and ERVs for their reliability, high quality, and variety of options that make them a great fit for even the most challenging of projects.

Autumn is HRV Maintenance Season

Across Canada, heating season is fast approaching. While it is still warm out, it’s an ideal time to open up your HRV and do the annual maintenance: clean the heat-recovery core, wash or replace the filters, and ensure that the drains are clear of any blockages. Our new and improved residential installation and maintenance guide offers many helpful tips for maintaining your HRV and keep healthy air flowing through your home during the winter months.

If you or your clients have an older HRV that is inefficient or is no longer functioning, Aldes HRVs are an easy choice for a replacement. Our compact top port units can hang in the same place as the old unit and connect up easily with flex duct to the existing ductwork. In many cases you can even connect the existing wall controls to the Aldes HRV without re-wiring. Contact us and we can help you assess whether your existing HRV can be replaced with a new Aldes ENERGY STAR® model.