How to Perform HRV Maintenance and Keep Your House Warm

A heat recovery ventilator (HRV) is a great option for homeowners who want to keep fresh air circulating throughout the home while minimizing heat loss in the process. If you have an HRV system, you should perform regular maintenance to ensure it stays in tip-top shape. In this guide, we’ll discuss a few tips for maintaining your HRV system to prolong its life and improve performance.

What Are the Main Components of a Heat Recovery Ventilator?

A heat recovery ventilator (HRV), which is a type of HVAC system add-on, usually consists of four main components:

• A core unit

• Ducts that carry fresh air from outside

• Ducts that carry exhaust air from your HVAC system

• Blower fans

Core Unit

The core unit is the portion of the HRV where the heat exchange takes place. It includes a counterflow heat exchanger, as well as a heat pump. Both the supply and exhaust ducts flow through the core unit, and as they do, heat is exchanged based on the demands of your HVAC system.

When it’s hot outside, the cool exhaust air is used to cool off the warm air coming into the home. This helps reduce the strain on your HVAC condenser and AC capacitor, as less cooling is needed. When it’s cold outside, the warm exhaust air heats the cold intake air, which, again, reduces the amount of work your HVAC system needs to do.

If you have a baseboard heating system or steam system instead of a forced hot air system, the HRV system can still remain active for your central air and remain dormant during the colder weather.

Fresh Air Ducts

The fresh air ducts pull air from outside your home, lead into the core unit, and eventually connect to your HVAC system for cooling or heating. These ducts sometimes run underground through a ground heat exchanger to condition the air a little before it hits your HVAC system for complete conditioning.

Exhaust Ducts

The exhaust ducts in your HRV take stale air from your living space, route it through the core unit, and vent outside.

When it’s warm outside, the cool air in the exhaust ducts can cool off warm intake air via the counterflow heat exchanger to reduce strain on your AC system. When it’s cold outside, the warm exhaust air heats up incoming fresh air to reduce strain on your furnace.

Blower Fans

Blower fans are the components in your HVAC system that circulate air, and they work the same way in an HRV system. When the fans are on, they force air through your system. When they’re off, the air in your ducts remains more or less stagnant. An HRV system uses several blower fans to circulate air in both the intake and exhaust ducts.

Now that you understand how the system works, we can discuss how to carry out heat recovery ventilator maintenance.

1. Turn Off the System Before Doing Maintenance

Whenever you're dealing with mechanical systems that run on electricity, it's always best to turn off and unplug the system first for safety reasons. Even if you’re just replacing filters, shutting the system down can prevent personal injury or damage to your system if something goes wrong.

2. Clean Air Filters Every 2 Months

For optimal performance, you should know how to clean HRV filters and carry out the cleaning process every two months. Since your system pulls in fresh air from outside, the filters are more likely to get clogged with pollen, dirt, and other debris, so cleaning them regularly is the best practice.

To do this, remove or open the door on the front of your unit, unclip and slide the air filters forward and remove them from the unit, and use a vacuum cleaner and rag to clean up any significant buildup. Soak the filter in warm water, rinse, and let dry. Then, put the filters back in the unit.

3. Replace Air Filters Once or Twice per Year

You should replace air filters in your HRV unit every six to 12 months. Exactly how often depends on how dirty your air filters are getting. If they get very dirty between cleanings and are showing signs of wear, err on the side of caution and replace them twice per year. If buildup is minimal, you can just do it once per year.

Don’t use a pressure washer to clean the air filters, because it can damage them. Running them under a sink faucet should do the trick.

4. Check Vents Regularly

It's not just the air filters you need to be concerned about: the HRV outdoor intake and exhaust hoods can get clogged with leaves and other debris that can affect the performance of your system.

If the vents aren't fully cleared, the airflow won't be as strong and the system won't work as well, so keep them clear. In the winter, be especially mindful of snow or frost building up and blocking the vents.

5. Inspect Other Parts of Your System

While keeping the air filters and vents clean will go a long way to ensuring your HRV is functioning optimally, there are other parts of the system that you’ll want to perform maintenance on, as well.

• Condensate drain: This is a tube that comes out of the bottom of the unit and disposes of condensation that builds up as heat exchanges between ducts; you can check it by pouring warm water into the drain pan to ensure proper flow. If it’s clogged, use a pipe cleaner or a mixture of baking soda and vinegar to clear it.

• Heat exchange core: Consult with your manual first before cleaning the energy recovery component in your system, which should at least be done annually. If you know how to clean the HRV core, you can do that when you clean your filters. You should vacuum the core and wash it with soap and water to prevent dust buildup. Remember to shut off your system and unplug it until it’s completely dry.

• Ductwork: Inspect the grilles that cover the duct ends to see if they need cleaning.

6. Contact a Professional

While you can do a lot HRV maintenance yourself, it may be best to contact an HVAC company near you to do the work. Even if you are keeping air filters and vents clean, you should still have a pro service your system annually. They can spot potential issues you may have missed and make repairs before issues get severe. They can also tell you when it may be time for a replacement.

An HVAC professional can also do more complicated maintenance, like ensuring the motor is working properly by reviewing belt wear, adjusting belt tension, cleaning dust and dirt from blower wheels, and lubricating bearings, all of which can extend the life of your system. You might even consider getting an HVAC maintenance service contract.

Additionally, you should consider testing the air quality in your home to ensure your HVAC system and HRV are working properly. The cost of indoor air quality testing is $400 on average. You can also use an indoor air quality checklist to evaluate the air in your home yourself.