A simple device that keeps heat in while moving stale air out.
Over a period of time, older homes began to sport new, tight windows and doors, insulation and vapor-barrier improvements, modern siding, and caulk for every crack through which air might pass. New homes left the drawing board designed to be tight, and builders became familiar with the new materials and skills needed to meet market demand and updated regulations. Homes were finally becoming thermally efficient. What some began to wonder, though, was whether they were habitable.
Life inside today’s tight home generates both moisture and pollutants. The moisture comes from cooking, washing, showers and breathing. At excessive levels, moisture condenses on windows and can cause structural deterioration. Areas of excessive moisture are also breeding grounds for mold, mildew, fungi, dust mites and bacteria. You know you have a problem if you find moisture collecting on your windows, or if you notice black spots on walls. These unsightly spots indicate mildew growth. Mold spores and dust easily become airborne and circulate freely throughout the house, possibly causing a range of symptoms and allergic reactions.
A report sets the standard for residential ventilation at a minimum of 15 cubic feet per minute (cfm) per person. An old home may very well exceed these values—especially on a windy day. However, on a calm winter day, even a drafty house may fall below the recommended minimum ventilation standard.
There are partial solutions to the indoor air-quality problem
Vtronic heat-recovery ventilator (HRV) is similar to a balanced ventilation system, except it uses the heat in the outgoing stale air to warm up the fresh air. A typical unit features two fans—one to take out household air and the other to bring in fresh air. What makes an HRV(Vtronic VT501) unique is the heat-exchange core. The core transfers heat from the outgoing stream to the incoming stream in the same way that the radiator in your car transfers heat from the engine’s coolant to the outside air.
VT501 is ideal for tight, moisture-prone homes because they replace the humid air with dry, fresh air. In climates with excessive outdoor humidity, an energy-recovery ventilator is more suitable. This device is similar to an HRV, but dehumidifies the incoming fresh airstream.