Energy Recovery Ventilation (ERV) is almost same as Heat Recovery Ventilation with an added feature. The former besides transferring heat can also transfer moisture between the two airstreams. As it transfers moisture as well, it allows the dry air in winter to have some moisture when it gets inside the rooms. This prevents too much dryness that usually prevails inside in the colder months. In summer the ERV makes the fresh air coming inside the house free of moisture. The humidity inside the rooms is lessened to some extent. This feature also keeps the heat exchanger warm and prevents freezing in winter.

How to know if you need energy recover ventilation in the house?

• You can get a blower test done in the house as a part of an energy audit. If rate of air exchange is 0.5 air changes per hour (ACH) or less, then it a good idea to have the house fitted with an ERV.

• Always try to monitor how long an odor lingers in the house; if it stays for long, then the house is airtight without proper ventilation. Buy an ERV to enable ventilation.

• If your heating and/or cooking equipment is not adequately ventilated, an ERV is recommended. In many houses the stoves do not vent out or the gas ranges are without hoods.

• If you keep chemicals inside the house, good level of ventilation is required. These substances often give out toxic gases in the air. Moreover these days the furnishing in the house also contains formaldehyde.

• In areas which are prone to high radon level, buying an ERV is a smart thought. However radon level cannot be controlled with ventilations solely.

These devices are best for houses that have supply and return duct for each bedroom and for all common living areas. The ducts should laid straight and have short length for good efficiency level. If you live is region where temperature dips quite low in winter buy an ERV with an additional device that prevent frost build up. The ERVs should be cleaned periodically to allow them deliver a good performance. It’s good to have a professional service the unit annually. You should change the filters and clean the drain after every couple of months.