Heat Recovery (HRV) & Energy Recovery Ventilators (ERV)

Interior quality of air issues have greatly increased since the the later part of the 1970’s when building technologies succeeded in creating energy-efficient "tight" homes. Heat recovery ventilators (HRV) have for ages been widely used in Canada and are also growing to be popular in the United States. Believe it or not, Canada has a nationwide ventilation law. During 1992 there was in excess of 125,000 systems sold there. Within the U.S., there are only 3 states that have ventilation laws and there are more than 15,000 units presently being used in the United States.

Contaminants inside of homes, which once escaped through cracks and crevices around doors and windows, are now confined inside producing an internal atmosphere that's typically Two to five times more polluted compared to outside the house. Family pet dander, mold spores, dustmites, allergens, cigarette smoke along with other pollutants amount to very poor indoor air quality. An Energy Recovery Ventilator  (ERV) or a Heat Recovery Ventilator (HRV) is an excellent solution to combat bad indoor air quality by delivering clean fresh air into your house whilst expelling stagnant air.

ERVs and HRVs utilize internal fans to pull fresh air flow in and then transfer stagnant air out of your house. The main element to efficient ventilation is the HRV or ERVcore -- which warms or cools down inbound fresh air, recapturing Sixty to eighty percent of the conditioned temperatures which would otherwise be wasted.

HRV vs. ERV - so what exactly is the difference?

There's two kinds of energy-recovery systems: heat recovery ventilators (HRV) and then energy recovery (or also called enthalpy recovery) ventilators (ERV). Both types incorporate a heat exchanger core, one or more fans that will help drive air through the device, and some controls. The primary difference between a heat recovery and an energy recovery ventilator is the means by which the heat exchanger core functions. With an energy-recovery ventilator, the heat exchanger exchanges a specific amount of water vapour together with heat energy, while a heat recovery ventilator simply only transfers heat. The part of the United States that you reside is going to determine the type of unit that's right for your family's needs. In most cases - HRVs are generally suggested for cold climates with lengthier heating seasons. ERVs tend to be used for milder, more humid climates with longer cooling seasons.

Installation & Sizing

HRVs/ERVs are normally sized to ventilate the entire house at a minimum of .35 air exchanges each hour. In order to calculate the lowest CFM requirements, you need to take the sq footage of the property (which includes the basement) and multiply by the height of the ceiling so you can get the cubic volume. Next, divide by 60 and multiply by .35.

The ideal way to configure the unit installation on an ERV or HRV is to always make a dedicated system of ducts to blow out old stagnate air from trouble spots (kitchens, bathrooms) and bring in fresh air to the more frequently used areas (lving rooms, bedrooms). Even though this is preferred, it is sometimes not possible - particularly in a retro-fit scenario. The most typical, and much easier installation is achieved by attaching the ERV/HRV supply and exhaust ductwork straight to the return air-duct of the home’s present forced air hvac system.