Retrofitting a New Hampshire Cape Home With Energy Recovery Ventilation

This is the second of a two-part series about retrofitting a home with a Zehnder Energy Recovery Ventilation system. Click here to read the first post in the series, which focuses on the importance of home indoor air quality for health.

Steeplechase Builders recently retrofitted an expanded cape home in southern New Hampshire for a couple with a Zehnder Energy Recovery Ventilation (ERV) system. The house had been air sealed to reduce leakage and save energy within the last couple of years, but lack of adequate ventilation caused indoor air quality and mold growth. Zehnder America provided design assistance, installation training, and technical support to Steeplechase Builders throughout the project.

The homeowners wanted the ERV system to ventilate all areas of the approximately 6,000 square foot home, which includes the basement. The challenge for the builders was that the owners didn’t want aesthetic changes to the home and they wanted all the ERV components to be tucked away.  Another challenge was that a section of the house is unheated during the winter,  canceling out the possibility of using one central ventilation system for the entire house; the heat would transfer to the unheated section of the home causing energy loss for the residents. These design constraints meant that Chris Smith, project manager for Steeplechase Builders and carpenter Nikos Zafirakis had to think creatively.

Chris and Nikos decided to install two Zehnder ComfoAir 350 ERV systems to overcome the challenge of energy loss during the winter. These two ERV systems promote home air quality by removing stale or contaminated air while replacing it with a constant supply of fresh, filtered air. One ERV services the heated section of the home, while the other services the unheated section. Steeplechase Builders used Zehnder air distribution components, including the ComfoTube ventilation pipe, manifold assemblies (with a silencer, fine filter, and activated carbon filters), supply diffusers, and return diffusers. Using Zehnder components allows the ERV to run more efficiently and quietly.

“The home has a gas fireplace on the main floor with a wood-framed chimney chase bump-out,” explains Chris. “The chase has a corresponding bump-out in the foundation and extends all the way to the attic. There was enough space on either side of the gas fireplace that we were able to run metal ducts from the ERVs in the basement up the chase to our distribution points in the attic.”

After discovering the chase, Chris and Nikos decided to change the design of the system, which was relatively simple to do. “I was able to call Zehnder, change the order, get some different manifold assemblies, and still have plug and play advantages,” explains Chris. “With this experience behind me, I can see how we can use Zehnder ventilation systems on just about any project.”

Chris and Nikos sought to minimize disrupting existing finished rooms to maintain the aesthetics of the house like the homeowners wanted. “We were able to install all the system components throughout an existing finished house and only had to make drywall patches in two locations,” marvels Chris. “This conflict avoidance took skill and patience on the part of my install partner, Nikos. Whatever time we took planning and exploring was more than compensated for by the time we saved avoiding patches.”

The large attic space that was used for distribution points had been previously inaccessible. Chris and Nikos installed an access hatch that allows for filter maintenance and brings the house to code compliance for firefighter access. They also installed plywood decking and utility lighting to facilitate periodic filter maintenance on the Zehnder ERV systems.

“We’re very proud of the results of this challenging installation,” says Chris. “It was comforting to be working with such well-designed equipment and to have ready back-up from the Zehnder America team when we needed guidance or encouragement.”