David Richardson/NCI
Interior Hvac Diagram
David Richardson/NCI
If you know what to look for, a visual inspection provides clues to unsafe operation. It's never good for one package unit to exhaust into the economizer of an adjacent unit.
National Comfort Institute
Before you jump on the heat pump bashing bandwagon, look at your duct installation practices first.

Seven Steps to HRV/ERV Maintenance

Oct. 1, 2004
Static type air-to-air heat exchangers are the solid-state electronics equivalent of the energy recovery ventilation market, regardless if you are facing

Static type air-to-air heat exchangers are the solid-state electronics equivalent of the energy recovery ventilation market, regardless if you are facing a metal or plastic plate exchanger or heat pipe device.

The equipment you service may be a heat recovery ventilator (HRV) transferring temperature differential or a plate energy recovery ventilator (ERV). In either case, proper maintenance is critical to bringing in needed fresh air, saving energy, and keeping building occupants comfortable.

The following are seven steps to provide routine maintenance for static type airtoair heat exchangers. These simple steps can be easily and efficiently performed by service technicians, thereby ensuring peak ventilation and efficient energy performance for many years to come.

1. Caution and safety

Start at the beginning and read the manufacturer's maintenance instructions. Products from various manufacturers have different maintenance requirements. Don't assume you can wash an energy exchange core just because that's the way you serviced your last unit. In addition, always disconnect power before servicing.

2. Inspect weatherhoods and screens

Remove any accumulated debris and clean both intake and exhaust hoods and associated screens. Debris isn't only a source of particulate pollution when associated with fresh air intake hoods; it can also reduce ventilation rates when restricting either intake and exhaust hoods. In addition, confirm that hoods are above snow drift levels and that intake hood velocities are 500 fpm or lower.

3. Inspect, service and adjust blower/motor packages

This standard service procedure is required for any air handler. While service differs between direct drive and belt drive packages, the service for both should include:

  • Pulley alignment and securing to shafts

  • Review belt wear and replace belts on a regular interval

  • Adjust belt tension and secure motor mounts

  • Clean dust and dirt from blower wheels and housings and motor vent openings

  • Lubricate blower and motor bearings.

4. Replace filters

Generally, filters should be replaced quarterly or every 2,000 operation hours. The timing for replacement can vary greatly depending on the amount of particulate in the airstreams and the type of filters that you use.

Furthermore, filter replacement should be scheduled in order to maintain specified airflow in each air stream. Make sure to use filters with a pressure drop and particulate arrestance comparable to the original filters. Use equivalent sized filters that fit securely in filter racks to minimize air bypass.

5. Inspect and clean the exchanger cores

Follow manufacturer's recommendations for cleaning the energy recovery component. Typically, this should be completed on an annual basis. Vacuuming with a soft brush attachment is frequently all that's needed or prescribed.

Some metallic heat exchangers may require washing, which could require removal of the cores from the unit. Care should be taken to avoid abrading or deforming the faces of the heat exchanger, because this will result in loss of airflow or energy performance.

6. General cleaning and inspection

Vacuum or use a damp cloth to remove accumulated dirt from the inside surfaces of the unit. Inspect seals and gaskets to ensure they're serving their purpose of isolating the two air streams and minimizing case leakage.

7. Confirm operation

Close and latch doors and access panels. Restore power to the unit and run through an on-off cycle to ensure proper operation. Schedule the next filter change and service.

Douglas Steege is vice president for marketing and sales with RenewAire LLC, a Madison, WI-based manufacturer of static plate energy recovery ventilators. Steege can be reached via email at dsteege@ renewaire.com.