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How HRVs and ERVs Operate in Chicago Area Homes

Energy efficiency is extremely important during the winter months, especially in cold-climate cities like Chicago. Many newer homes have been built with an emphasis on energy efficiency, however this comes at a cost. Efficient, airtight homes often lack sufficient ventilation, which is why many homeowners turn to ventilation systems like heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs)

Why Your Home Needs Ventilation 

When a home lacks ventilation, moisture can accumulate in the air. Although moisture in the air is completely normal, it can create problems if it's allowed to build without ventilation. Excess moisture can lead to stale air, which can subsequently lead to mold, mildew, bacteria and even structural damage.

Heat recovery ventilators and energy recovery ventilators combat excess moisture and contaminants while still maintaining high levels of efficiency. Both systems target stale air and replace it with fresh air. While they're both based on the same concept, they work in slightly different ways.

Heat Recovery Ventilators

A heat recovery ventilator can either be installed with a furnace or it can be used independently. The ventilator uses two fans to replace old air with new. One fan targets the stale indoor air and blows it outside while another pulls in fresh outdoor air and circulates it through the home.

What makes a heat recovery ventilator different from traditional ventilators is a heat-exchange core that takes heat from the old air and transfers it to the new, fresh air. The idea is similar to the operation of a car's radiator, which transfers heat from the engine to the air outside the vehicle. This method of heat transfer allows you to bring new air into the home without wasting warm for which you've already burned energy.

Most heat recovery ventilators are approximately 85 percent effective in transferring heat from old air to new. That means you'll lose some efficiency as the system replaces your indoor air with outdoor air. However, losing 15 percent efficiency is still more efficient than simply opening a window to get some fresh air.

Heat recovery ventilators also have different fan speeds to allow a homeowner to customize the airflow depending on the environment. A low setting may be appropriate for a modest home with only one or two people inside, while a large home filled with guests may require a higher rate of ventilation.

Energy Recovery Ventilators

Energy recovery ventilators (ERVs) are based on the same idea. Like HRVs, energy recovery ventilators also push old air outside and replace it with newer, fresher air. Similarly, they also transfer heat from the old to the new air to reduce energy waste.

Energy recovery ventilators differ from heat recovery ventilators in that they don't just transfer heat; they also transfer the latent heat from the moisture in the air. Latent heat is produced when moisture changes forms. A good example is the heat that's produced when boiling waters begins to change from liquid to gas.

Latent heat is a significant part of the heat in a home's air, but it's not transferred by heat recovery ventilators. Energy recovery ventilators are able to transfer latent heat, which makes them effective at controlling moisture and energy efficiency.

In choosing between an HRV or an ERV, it's helpful to consider the climate and outdoor environment. Heat recovery ventilators do better in climates with cold winters and summers that aren't incredibly humid. Since the heat recovery system simply replaces the indoor air with the outdoor air, it could bring in moisture in a humid climate. An energy recovery ventilator may do better in a humid climate since it's able to pull the moisture out of the air for energy use.

For more information on heat recovery ventilators and energy recovery ventilators, please contact us at Comfort24-7.com. Our dealers proudly serve Chicagoland, northwest Indiana and southwest Michigan.

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