Drainwater Heat Recovery Devices Moving into Building Codes
Ecodrain vertical drainwater heat recovery unit
More than 60,000 devices drainwater heat recovery systems have been installed in North America. In a typical single family home, a drainwater heat recovery (DHR) device can reduce the amount of energy used for domestic hot water by 15 percent to 22 percent.
A DHR is a heat exchanger that transfers heat from hot shower waste water to cold incoming water, effectively providing a larger capacity of hot water. For example, a 30-gallon waterheater will perform like a 40-gallon or 50-gallon unit. It operates when water is flowing down the drain at the same time hot water is drawn, such as during a shower. The devices work with both tank-style and tankless water heaters.
According to RESNet, "water heating is a large energy load in homes and its contribution to total home energy load has increased in recent years as building envelops and mechanical systems improvements have resulted in significantly reduced energy consumption."
The systems are required under the IECC 2015, which forms the basis for building codes in some jurisdictions in the United States. In some locations, the systems are required under local codes such as Ontario and Manitoba in Canada. In Georgia and California, DHRs are under review for inclusion in state building codes. Currently Georgia's building codes are based on the 2009 IECC, which does not require DHRs.
The DHR systems also contribute to green building program points and also contribute to a home's HERS index, administered by RESNet.
According to Green Building Advisor, installing a DHR can lead to a 2 to 4 point reduction in the HERS score, depending on the climate zone.
Most DHRs are installed vertically, but EcoDrain has pioneered horizontally oriented products as well. EcoDrain is also developing vertical products for markets that require vertical installations, according to President David Velan.
Horizontally mounted units provide an easy installation in single story and slab-on-grade construction where there isn't sufficient space to install a DHR that may be up to 5 feet long under the shower drain. Vertical-style systems can be installed in a home with a basement, or in a two-story home with the shower on the second floor.