Heat recycling – keep the heat, exchange the air.

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Cindy Parker

Heat Recovery Ventilators (HRVs) ensure that the air inside your home or building includes fresh air from outside. As we eliminate air leaks, caulk every crack and insulate walls, floors and ceilings – our air tight homes can get a little stuffy. Although it’s great to bring in outside air – you don’t really want a cold winter breeze flowing through your house. HRVs and Energy Recovery Ventilators (ERVs) handle the task of providing fresh air while recovering heat from the air that is released – or exhausted, from your home.

It is essential to exhaust air from your indoor environment. Indoor air becomes “polluted” with indoor activities such as cooking, showering, using cleaning compounds – almost any indoor activity results in odors, moisture or chemicals being released to the indoor atmosphere.

Oxygen is pulled from your indoor environment while operating your furnace, fireplace or woodstove. People and pets also consume oxygen and continually release carbon dioxide (among other gases) – changing the composition of the indoor air.

HRVs are mechanical ventilation systems that take care of removing stale air and providing fresh, preheated air to your building. The fresh air is “preheated” by passing through an air to air heat exchanger. As warm (stale) air is leaving the home, cool fresh air is entering. The opposing air streams do not mix as they pass through the heat exchanger “box.” This heat exchanger is part of your central air/heat system. The cool air entering the heat exchanger is warmed by the stale air that is leaving. Supply and return air ducting is fundamental for this type of whole house ventilation.

If your home (or commercial building) does not have an HRV system, they are usually not too difficult to have installed. The payback is generally realized very quickly by the change in comfort and in the fact that the air you are heating has a higher temperature than straight, unconditioned outdoor air. Even if you have a baseboard or hydronic heating system, you may consider central exhaust ducting and an HRV to compensate for kitchen and bathroom exhaust fans and to provide filtration to your fresh, make-up air. This is also a good application to provide whole house ventilation and better heat distribution for folks who use woodstoves.

HRVs may use one or two fans to control and regulate the air exchange process. The systems require very little maintenance. For Michigan, it is recommended that HRVs have an automatic defrost cycle to prevent ice and frost buildup on the air inlet side of the system.

Pricing for HRV systems runs from around $700 to $2,000. Installation should be done by a licensed contractor.

ERVs (Energy Recovery Ventilators) operate much the same as HRVs but take into account the latent heat and moisture content of the air. These systems are great for helping to manage the relative humidity in your building on a year-round basis.