Is Your House Too Tight? ERV/HRV Basics for Homeowners
We often get the question, “Won’t spray foam make my house too tight?” Our answer for this is to remember the saying, “Build them tight, ventilate them right.” In fact, most houses are not too tight – windows and doors leak plenty of air. Yes, urethane spray foam insulation will make your house tight, but that’s a good thing. We do recommend installing air-to-air exchangers (ERV or HRV) to allow stale air to be exchanged efficiently.
Even if you are using standard fiberglass insulation, it may be a good idea to add mechanical ventilation to your home for mold prevention. Controlled mechanical ventilation can improve indoor air quality.
Insulation Foam Spray Kansas City
When we meet with homeowners to discuss the use of urethane spray foam, we highlight the importance of installing a ventilation system properly calculated by a professional.
Heat Recovery Ventilators (HRV) exhaust stale indoor air outside and bring fresh air inside. The outside air passed through a heat exchanger picking up heat (or coolness, depending on the season), from the warm indoor air as it passes by the heat exchanger. The air never mixes. This image does a great job illustrating the exchange.
Energy Recovery Ventilators (ERV) work similarly, but help remove humidity from incoming fresh air. These systems work best in warmer climates.
The video below explains the differences between the two systems in a bit more detail. While an HRV system just exchanges heat, an ERV system is slightly more efficient because not only does it transfer the thermal energy in the air, it also transfers the latent energy in the water vapor.
Either system can be set up to duct with or without the HVAC system. However, it is best to connect it to the HVAC system return and supply system. Be sure to consult with an HVAC design professional for information as it pertains to the specifics your home.
Do You Need an HRV/ERV?
To determine whether or not an HRV/ERV is needed for your home, it is best to conduct a Blower Door Test. This diagnostic tool tests the airtightness of a home using a special fan to ensure that air sealing work is effective. A Home Energy Rater certified by RESNET will check the Air Changes Per Hour (ACH). They will be able to tell you if you need to mechanically ventilate. If so, ensure you work with an HVAC professional qualified to design a system to meet the requirements.
If you are interested in talking with an HVAC professional, but aren’t sure where to start, we would be happy to provide recommendations based on contractors we have worked with. If you want to learn more about the ways our urethane spray foam insulation can benefit your home, give us a call. We would be happy to meet with you!
