With the trend to new homes being sealed tight to conserve energy, all new homes will now include an Energy Recovery Ventilators (ERV) to act as the ‘lungs” for new homes. Please note that these devices are very different from the previously mandated HRV’s. The HRVs brought in fresh air but also brought in excessive humidity in summer and excessively dry air in winter. The ERV removes moisture from incoming air in summer and adds moisture to incoming air in winter. It is this ability to moderate humidity that makes the ERV so much better.
These devices can greatly improve air quality in your home. Unfortunately, there is a lot of confusion on the part of homeowners and even some professionals and home inspectors about their proper use.
To get the facts on this we interviewed Jean-Guy Marchand C.E.T C.I.M. from Venmar.
Blythwood Homes specializes in building upscale bungalows for empty nesters and retirees. The advice here relates to owners of our typical homes which are about 1,600 to 2,000 sq ft. on the main floor and similar size in the basement.
The ERV maintains fresh air in the home by bringing fresh air inside and exhausting stale air outside. Here are some guidelines for a couple living in a tightly sealed home:
- Bathroom and kitchen odours should be exhausted directly to the outside. (It is best to have a timer on bathroom fans so you can let them go for about 30 to 60 minutes after a shower)
- To maintain air quality set the ERV controls to the intermittent on off cycle.
- This continuous intermittent setting should be maintained all year round.
- If you have a party or are cooking food with odours you can turn the control to high for an hour or so.
HOW THE ERV WORKS
The ERV heats (or cools) cold (or hot) air coming from outside with air being exhausted from inside to save energy. It also removes humidity from incoming air in summer and adds humidity to incoming air in winter.
Don’t run the ERV in summer as it will create humidity.
Not True. The ERV contains an Energy Recovery Core (made of polymerized paper and aluminum) that decreases the humidity of incoming air in the summer by up to 60%. (This Recovery Core acts like a membrane moving humidity for the incoming air to the outgoing air.) As a result, your air conditioner system will run less this way then if you just opened a window.
Don’t run the ERV in the winter as it will dry out the home.
Not True. In winter the ERV will recover up to 60% of humidity from the outgoing air and add it to the incoming air. As a result, continuous operation is usually appropriate. Continuous operation in very cold weather could result in humidity levels getting too low. A humidifier on the furnace can compensate for this.
In winter we recommend that you monitor the level of humidity using a humidistat centrally placed in the home and turn the ERV down if humidity gets below 35%.
Running an ERV all the time is Expensive?
No not at all. In the summer the ERV takes in fresh air but with reduced humidity so you’re A/C runs less. Proper use if the ERV controls moisture and helps avoid expensive mold issues.
We recommend that our buyers run their furnace fan continuously. This circulates the air in your home and takes humid air away from the basement. The hydro cost to run your furnace fan continuously for one year about $35.
So, lets summarize to make it simple:
- Run your ERV on the intermittent on and off cycle all year long.
- If you have more people or odour causing activities put it on high until the air clears.
- In winter, monitor the humidity level in your home. If humidity drops below 35% you should turn up your humidifier or set your ERV to a lower setting.
- When the air outside is extremely cold, you can expect to have condensation on the windows. Ultimately there is no solution to solve condensation on your windows. You can lower the humidity in your home to deal with this or just wipe the condensation off on cold days. We are sorry to say this will happen with all new homes. After all we are in Canada Eh!
The Venmarr AVS CR 12 ERV used by Blythwood Homes is simple to maintain.
Twice a year, unplug the unit, open the side door and remove the two filters. Wash the filters, replace and plug back in. You can also clean the Recovery Core by vacuuming once a year.
I hope this summary takes the mystery out of the operation of your ERV. It works, so use it!