Zehnder Interview Series: HRV System Planning


Interviewer: John, could you introduce yourself?

John Rockwell: My name is John Rockwell. I’m a Technical Sales Engineer with Zehnder America. I’m trained as an architect, and I design Zehnder Comfosystems for residential and small commercial applications.

Interviewer: Why is it important to have matched HRV and air distribution components?

Zehnder Comfosystems include every needed component for a balanced ventilation system: HRV, ductwork, silencers, controls, registers, diffusers, grills, etc. They are designed to work together, so customers do not have to cobble a system together from varied and different suppliers.

Interviewer: Where should the HRV be placed in the home?

John Rockwell: It is crucial that the entire system of HRV and distribution be within the thermal enclosure of the building. Locating it in a chilly basement or cold attic defeats the purpose of high-efficiency heat recovery and may affect comfort, as the supply air may be cooler than desired. Also, the HRV location should minimize excessive lengths of ductwork for supply and return air. Finally, if the HRV is near an exterior wall, the ducts which connect to outside – fresh air intake and exhaust air – can be shortened – a good thing in cold climates.

Interviewer: What advice do you have for choosing the right space to put the central HRV unit?

John Rockwell: While it’s a very quiet system, it is a piece of mechanical equipment so you don’t want it directly in a visible space. It’s best suited for a mechanical room, a laundry room or a similar designated space. Also, it’s very important to keep it within the building’s thermal enclosure, so that it’s not subject to the temperature swings of a hot attic, or a really cold basement space.

Interviewer: Can you tell me about the Zehnder design service?

John Rockwell: A technical sales engineer will review a customer’s architectural drawings, indicate the optimum location for the HRV or ERV, and where supply and exhaust points should be located. From this, a detailed quote and system layout are provided to the customer. This helps the installer to locate the HRV and air distribution components in the building.

Interviewer: Why should the HRV be separate from the central HVAC system?

John Rockwell: We believe in 24/7 balanced ventilation. Which means fresh air is supplied to rooms and stale air is removed from rooms at all times. If that system is part of a central HVAC system with ducting, it’s complicated to optimize the system for constant ventilation but only intermittent heating or cooling.