5/20/2015

Zehnder Interview Series: HRV and ERV FAQs

Interviewer: Could you please introduce yourself, Micky?   

Micky Dunegan:  My name is Micky Dunegan. I am the Technical Sales Representative for the Southwest region, which includes California, Arizona, Utah, and Nevada.

Interviewer: What factors go into considering an HRV vs ERV?

Micky Dunegan: There is not a definitive answer regarding this question. There are important factors to consider that are based on geographic location as well as occupant density and the humidity level in the home.  In situations where either can be used, it’s often recommended to use an HRV because of the higher efficiency.  Some HRVs/ERVs (such as Zehnder’s systems) have a removable core so that the best option can be used for the best time of year.  Have the peace of mind that when you send over your project plans, Zehnder makes a customized HRV vs ERV recommendation on each project.

Does the HRV device need to be in a conditioned space?  Where are some places it’s commonly put in the home?

While there is minimal heat loss in our well-insulated units, our recommendation is that our units, as well as our distribution components, are located within the thermal envelope.  Our units are commonly installed in mechanical rooms as well as conditioned attics, mud/laundry rooms and closets as they are very quiet.

If you have an HRV or ERV, do you still need a bath fan?

We design our systems to meet or exceed the minimum continuous ventilation requirements for bathrooms, therefore, eliminating the need for intermittent bath fans.

Why is an HRV or ERV system a better approach than periodically opening doors and windows for fresh ventilation?

There are a number of reasons. One of which is, the peak level of benefit regarding proper ventilation for the occupants in a dwelling are had during sleeping hours. Doors and windows are best kept closed and locked for safety reasons and of course during the heating and cooling season to avoid energy loss and physical discomfort. Other valuable benefits include the removal of elevated levels of VOC’s and CO2 that are likely to occur. The same applies to an unoccupied home. Excess moisture mitigation, energy recovery, and overall good indoor air quality must also be achieved when the home is unoccupied at which time windows and doors are closed and locked. Outdoor air quality can be an issue as well.  Keeping doors and windows closed reduces the introduction of airborne allergens and pollutants into the home in which case a superior ventilation strategy is necessary.

Does running a Zehnder HRV or ERV system use a lot of electricity?

Running a Zehnder HRV/ERV requires very low energy consumption. The only moving parts in our units are two ECM DC radial fans that are very quiet and highly efficient.

Who usually installs a Zehnder HRV or ERV system?

While an HVAC contractor would appear to be the obvious candidate to install our systems, it is not uncommon for the general contractor and in some cases the homeowner to perform the installation themselves. Our distribution system is very installer friendly and requires very few tools and the design layout that is provided by our design team serves as a very effective and convenient “road map”  Helpful and comprehensive installation videos are available on our website to aid and guide in the installation process as well.