How to properly maintain your mechanical ventilation system
Posted by Grant Bowman on September 8, 2015
It is important to maintain mechanical ventilation systems in your home and keep them in good operational order. Otherwise you risk the possibility of unwanted conditions arising in your home. In this blog, I’ll cover some of the common ventilation systems in our homes, such as: 
• Heat Recovery Ventilator (HRV): This is one of the most energy efficient ways to ventilate your house in Minnesota during the winter. It is a balanced system, in that it brings in the same volume of air as it exhausts outside. The exhausted air helps to preheat the incoming fresh air. To keep a heat recovery ventilator system in tip top performance, you need to clean or replace the filters in the unit and make sure the intake hood on the outside of the house is clear of cottonwood seed and other airborne debris that will clog the incoming air screen. This in turn will change the balanced pressures within the house, creating a negative pressure. You will also need to clean the heat exchanger inside the unit once it starts to foul. Don’t forget about the condensate drains/pans that also need to be cleaned.
• Energy Recovery Ventilator (ERV): This is also an energy saver, but not as common in cold climates like Minnesota. Instead of a heat exchanger, energy recovery ventilators use a desiccant wheel. This allows the heat energy to transfer along with some of the moisture in the air. This helps with summer ventilation in keeping the humidity from outside coming into the house with the fresh air. They need similar upkeep with filters and intake screens to keep the balance correct and the unit from becoming fouled. See the manufacturer’s requirements for cleaning the desiccant wheel.
• Exhaust Fans/Passive intake: This system requires that an exhaust fan on the highest level of the house is kept running continuously. It also requires that fresh air is allowed to passively enter the house through an intake pipe as the exhaust fan creates a negative pressure to draw the fresh air in. This fan normally does not have any means for filtration, so it will need to be removed and cleaned periodically. Also, the intake screen needs to be kept clean as it does not have a forced movement of air to overcome a dirty screen. Do not block the intake inside the house, as it may create a condition where your fuel burning appliances will not vent properly and spill flue gasses into the house.
Ventilation is important, and many things can influence how well it works or if the house has the proper balance. It is a good idea to have a professional contractor who specializes in indoor air quality to test your mechanical ventilation system for proper operation and balance.
