Energy recovery ventilators (ERVs) provide fresh air while maintaining indoor comfort and reducing energy costs. They’re valuable in tightly sealed, well-insulated houses where air quality can be a concern. This Old House plumbing and heating expert Richard Trethewey shows the functionality of an ERV in the video above. Keep reading for everything you need to know about energy recovery ventilators.
What Are Energy Recovery Ventilators?
Energy recovery ventilators exchange stale indoor air with fresh outdoor air, simultaneously transferring heat and moisture between the two air streams. They’re a good choice in homes that are stuffy or prone to moisture and mold.
How Does an ERV Work?
There are five primary components of an ERV: ductwork, fans for circulation, filter, heat exchanger core, and system controls. Here’s a look at how ERVs work:
- The ERV pulls air from bathrooms, basements, and other areas, which is run through the filter.
- The ERV pulls fresh outdoor air into the system.
- The two air streams pass through a heat exchanger core, where energy transfer occurs.
- Fresh, conditioned air is distributed throughout the home, and the stale air is expelled outside.
The heat exchanger core is the heart of the ERV system. It allows for the transfer of heat and moisture between the incoming and outgoing air streams without the air actually mixing.
What Are the Benefits of an ERV?
The biggest benefit ERVs offer homeowners is improved ventilation, but they can also provide the following:
- Improved indoor air quality: Stale air can collect contaminates, but the ERV filters out particles and allergens.
- Reduced energy load: Modern ERVs can recover up to 80% of the energy from exhaust air, depending on the model and operating conditions. This means they can reduce energy costs, especially in hot and humid climates.
- Consistent indoor temperature: In the winter, the ERV transfers heat from the warm exhaust air to the cold incoming air, reducing the load on your heating system. In the summer, heat from the warm incoming air is transferred to the cooler exhaust air.
- Better humidity levels: ERVs transfer moisture between air streams, lowering humidity levels and reducing mold growth potential. In winter, this transfer can also help prevent dryness.
- Reduced HVAC load: Since the ERV helps to maintain a consistent indoor temperature, the HVAC doesn’t have to work as hard, extending its lifespan while also lowering energy bills.
- Smart home system integration: Modern ERVs can be controlled via smartphone apps and home automation systems, allowing for automatic adjustments based on indoor and outdoor conditions, scheduling, real-time air quality monitoring, and remote operation. They can also be integrated with HVAC systems for improved performance.
ERVs are continuing to improve. In the future, expect to see advanced filtration systems, integration with air purification technologies, machine learning algorithms for predictive operation, and more efficient heat exchanger designs.
Installing an ERV
To purchase the right ERV for your home, consider climate conditions, your existing HVAC system, home size, home layout, and local building codes and regulations.
A licensed HVAC technician can help you find the right unit for your home. We recommend professional installation to ensure the ERV works with your home’s existing systems and to improve overall performance. The HVAC technician’s expertise can help prevent potential issues that could arise from improper installation.
Cost of Installation
The cost of installing an ERV system can vary, depending on factors such as the size of your home or existing infrastructure. You can expect to pay at least $2,000 for a professionally installed ERV. The investment pays off through improved air quality and energy savings over time.
Maintaining Your ERV
Your ERV needs to be regularly maintained to keep it running efficiently. Homeowners should perform the following tasks:
- Check and clean fan blades and housing.
- Check that ductwork is free from obstructions.
- Clean or replace filters every three to six months.
- Inspect and clean the heat exchanger core annually.
- Schedule professional servicing once a year.
- Verify proper operation of controls and dampers.
Common issues with ERVs include reduced airflow due to clogged filters, unusual noises from the fan components, ineffective humidity control, and faulty controls or sensors. Some of these issues, such as clogged filters, can be repaired by homeowners. Others may require a professional. Address any problems you notice right away to prevent further damage to your ERV
ERVs vs. HRVs
ERVs and heat recovery ventilators (HRVs) transfer heat between incoming and outgoing air streams. However, ERVs also transfer moisture and can help cool the home, while HRVs can’t.
ERVs are a good choice for climates with high humidity or for homes where maintaining consistent indoor humidity is a priority. HRVs can be a better choice for climates with mild humidity or in colder environments, as ERVs can have trouble functioning in cold temperatures.
Choosing between the two depends on existing humidity issues, home occupancy and activities, local climate conditions, and personal comfort preferences.