A Heat recovery ventilator has a few jobs to do and does a good job at it as long as its being maintained and is set up properly.
So what does a Heat recovery ventilator do?
Out with the old
One of the jobs of the HRV is to remove stale air from inside the house. Instead of individual bathrooms, kitchens and laundry room exhaust fans that remove the moist warm air and discharge it outside, the HRV is a single point fan that draws air from all these locations and other ductwork in the house and discharges it to the exterior.
In with the new
The HRV draws air in filters it and distributes the air throughout the home. we want to be in somewhat of control of how much air enters the home, where it comes from and where it goes. If we don't provide makeup air, air will be drawn in from any points, typically around doors and windows, this can create drafty uncomfortable living conditions.
Warming things up
The standard bathroom fan works well to get rid of stale humid air, but not very efficient to take air that has been warmed and just blow it outside. So the HRV takes the heat from the exhaust air and transfers it to the cold incoming air with the use of an exchanger core. The 2 air flows never touch or mix, it just transfers the heat.
Why HRV's are becoming more important
As seal any air leaks to improve energy efficiency, your heating bill will decrease. If you have the same air inside your home your indoor air quality will decrease, and that's why we started using HRV's. In shorty, they increase energy efficiency while helping to maintain good indoor air quality.
Do I need one in an old home?
The short answer is NO, but you may want to consider installing one. If you have installed new windows, furnace or upgrading insulation levels, all these upgrades change how the components of the house work together. If you are getting condensation on your windows, need to run a dehumidifier in the winter, feel like you have stuffy air or feel the need to open windows in the winter, these are all signs you may benefit from an HRV.
Keeping a balance
HRV's should be operational all year and never leave it unplugged. HRV's are essential in keeping the air you breathe healthy and controlling humidity to prevent mould.
New things always have a learning curve
In the first few years that HRV's were installed, there were many misconceptions on how to balance when they should be operating. If you have lots of cold air and humidity problems in your house it would be good to get your HRV balance and serviced again.