Heat Recovery Ventilators and How They Work
Posted on February 28, 2018
A heat recovery ventilator is a simple device that moves stale air out and keeps heat in. It has a number of components including a defrost damper, speed control, blower, heat exchange core, power cord, and many others. Most homes today are squeezed on space and generate both pollutants and moisture. The moisture normally comes from activities such as washing, cooking, showering, and even breathing.
When the moisture reaches excessive levels, it condenses on window surfaces and this may negatively impact the structural integrity of your home. Apart from that, excessive moisture may create breeding grounds for fungi, mildew, mold, bacteria, and dust mites.
Ventilation through Windows
The American Society of Heating, Refrigerating, and Air Conditioning Engineers came up with a standard for residential ventilation at 0.35 air changes per hour on the minimum. The standard also specifies that ventilation should not be less than 15 cubic feet per minute per person. These are values that an old home may exceed particularly on windy days. However, as the seasons change and winter comes, even drafty houses may not meet the minimum penetration standards.
Among the solutions there are for poor indoor air quality include installing an electrostatic filter to reduce airborne contaminants, local exhaust fans to remove excess moisture in the laundry, bath, and kitchen area.
According to ventilation experts, there is a better whole-house solution to poor indoor air quality which is balanced ventilation. The good thing with balanced ventilation is that one fan blows the stale air out of the house while the other one replaces it with fresh airflows. The only problem with this is that for cold air, you will have to heat it up which costs money.
Holding the Heat
A balanced ventilation system works on a similar principle to a heat recovery ventilator (HRV). The only difference is that the HRV uses heat from the outgoing stale air to warm up the fresh incoming air. This is where the recovery comes in.
A typical HRV consists of two fans; one which blows out household air and the other one fans in fresh air. The heat exchanger core is what makes the HRV unique. It is in this core where heat from the outgoing stream is transferred into the incoming stream. The core comprises a series of alternating passages that act as channels for both outgoing and incoming air streams. As the streams move through, heat from the warm side of each passage is transferred to the cold. That said, the air streams never mix.
HRVs come in different models and qualities. There are those models which have a capacity to recover up to 80% of the heat. This makes ventilators energy efficient systems. To install HRV systems, it may cost you between $2,000 and $2,500 depending on your specific situation. The heat recovery ventilator may also be effective during summer, but its popularity and application is mainly in winter.