Heat recovery ventilators (HRV) started showing up in new homes since about 2008. HRVs bring fresh air into the house and reclaim or recover about 80 percent of the heat from the stale air that is being drawn out of the house.  The need for these systems started when building codes began requiring homes be built tighter and more energy efficient. Homes in the past leaked enough fresh air into the home that a special ventilation system was not needed.

These systems have air filters that need cleaning regularly depending on how much they run. I have not yet found a single HRV that had been serviced and cleaned during a home inspection. On average, they need cleaning at least twice per year. The cleaning task is not difficult when the instructions are followed in the owner’s manual.  People are just not told what the systems do and they need regular cleaning. HRVs are about a foot tall and two feet long and are found mounted close to the furnace and hung from the ceiling. Now that you are aware they need cleaning, it is time to find that manual and get started cleaning your unit.

Here is a good HRV YouTube video to get you started on cleaning your system: https://www.youtube.com/watch?v=pxjwM_P_J14

WHY ARE MY WINDOWS SWEATING
 
If you are having trouble with water collecting on the inside of your windows during cold weather, you are not alone. This can cause water stains, wood damage, mildew and even mold. If you are looking for a way to stop this water problem, we need to understand what is causing the water to form in the first place.   
When air warms, it expands which allows it to hold more moisture. As it cools down, it contracts until it reaches the saturation point and releases this excess water in the form of condensation.
Everyday activities in your home, such as; cooking, showering, using unvented gas heat, and even breathing add moisture to the air. When this warm humid air comes in contact with cold window glass, it cools and condenses. To reduce this problem, you need to reduce the amount of moisture in the air. The homes moisture level is measured by humidity gauge. Below are some suggestions that will help:

• Always run a vent fan in the bathroom when you shower or bath, and leave it on for 15 minutes afterward. Also, make sure to leave the door almost closed so the fan will exhaust most of the moisture and not allow it to escape into the rest of the home.
• Check for and seal up any cracks around windows.
• Lower your thermostat to 66°-68° F. This lowers the difference between the inside temperature to the outside temperature.
• Check to make sure your clothes dryer is vented properly to the outside.
• Unvented gas heaters produce lots of moisture in the home, so consider reducing this heaters usage.
• Check to see whether the kitchen cooking exhaust fan moves steam and fumes outside the home. Many over-the-range microwave ovens are setup to recirculate cooking by-products through a metal screen and back into the room. These can be installed and setup either way.
• If you have only single pane windows, consider adding storm windows to those or consider replacing the older single pane windows. All new windows will have double or triple pane glass.
• If you are still having problems, you will need to consider purchasing a dehumidifier. Below is a list of recommended indoor humidity levels according to the outside temperature.
  • Outdoor temperature over 50˚F, indoor humidity levels shouldn’t exceed 50% anytime during the year
  • Outdoor temperature between 20˚F to 50˚F, indoor humidity levels shouldn’t exceed 40%
  • Outdoor temperature between 10˚F and 20˚F, indoor humidity levels shouldn’t exceed 35%
  • Outdoor temperature between 0˚F and 10˚F, indoor humidity levels shouldn’t exceed 30%
  • Outdoor temperature between -10˚F and 0˚F, indoor humidity levels shouldn’t exceed 25%
  • Outdoor temperature between -20˚F and -10˚F, indoor humidity levels shouldn’t exceed 20%
  • Outdoor temperature at -20˚F or lower, indoor humidity levels shouldn’t exceed 15%