ERV Sizing Calculator

FAQs

1. How do you calculate ERV size? ERV size is calculated based on factors such as building size, occupancy, climate, and ventilation requirements. A simplified estimation can be made by considering the building area, number of occupants, and desired air changes per hour (ACH). However, for accurate sizing, consult an HVAC professional.
2. How many CFM do I need for an ERV? The required CFM (Cubic Feet per Minute) for an ERV depends on the specific building’s ventilation needs. A typical residential ERV might range from 50 CFM to 200 CFM, while commercial ERVs can be much larger, often exceeding 1,000 CFM.
3. What is the measurement of ERV? ERV capacity is measured in CFM, which represents the volume of air exchanged per minute.
4. What should ERV be set to? The ERV should be set to achieve the desired ventilation rate, typically expressed as ACH (Air Changes per Hour), which varies depending on the application. Common ACH targets for homes are 0.35 to 1 ACH, while commercial settings may have different requirements.
5. Can you oversize an ERV? Yes, oversizing an ERV can lead to problems such as inefficient operation, temperature imbalances, and increased energy consumption. Proper sizing is crucial to avoid these issues.
6. How much humidity does an ERV remove? ERVs do not remove humidity. They transfer heat and moisture between incoming and outgoing air streams to maintain indoor humidity levels.
7. How do I calculate how much CFM I need? Calculate the required CFM by multiplying the volume of the space (length x width x height) by the desired ACH and dividing by 60 (minutes). CFM = (Volume x ACH) / 60.
8. Should I run my ERV continuously? Running an ERV continuously depends on the building’s ventilation needs, climate, and indoor air quality goals. Some ERVs have variable speed settings to adjust airflow based on demand.
9. Is 600 CFM enough? Whether 600 CFM is enough depends on the specific application and ventilation requirements. It may be sufficient for some residential spaces but inadequate for larger commercial settings.
10. What does it mean if your ERV is high? If your ERV has a high CFM rating, it indicates that it can exchange a large volume of air per minute, which can be suitable for larger spaces or those with higher ventilation needs.
11. How do I know if I need an ERV? You may need an ERV if you want to improve indoor air quality, manage humidity levels, or meet building code requirements for ventilation. Consult an HVAC professional to assess your specific needs.
12. What is the difference between an ERV and HRV? ERVs (Energy Recovery Ventilators) and HRVs (Heat Recovery Ventilators) both exchange indoor and outdoor air but differ in how they transfer heat and moisture. ERVs transfer both heat and moisture, while HRVs primarily transfer heat.
13. What are the disadvantages of ERV? Disadvantages of ERVs can include cost, complexity of installation, maintenance requirements, and the potential for overventilation if not properly sized and controlled.
14. Should I turn off my ERV in the summer? It depends on your climate and indoor air quality goals. In some cases, reducing ERV operation in the summer when outdoor air is hot and humid may be beneficial to maintain comfort and energy efficiency.
15. Does ERV need a drain? ERVs typically do not require a drain. They transfer moisture between air streams but do not produce moisture themselves. However, condensation drains may be needed for some ERV installations in specific conditions.
16. Where do you mount an ERV? ERVs are usually mounted in mechanical rooms, basements, or other suitable locations in the HVAC system’s ductwork.
17. What kind of duct do you use for an ERV? ERVs use standard HVAC ductwork made of materials suitable for the application, such as galvanized steel or flexible ducts.
18. Where should ERV vents be placed? ERV vents should be strategically placed to ensure balanced ventilation throughout the building. Common locations include bathrooms, kitchens, and living areas.
19. Does an ERV bring in fresh air? Yes, an ERV brings in outdoor air while simultaneously exhausting indoor air. It helps maintain indoor air quality by exchanging stale indoor air with fresh outdoor air.
20. Does an ERV help with condensation? ERVs can help manage indoor humidity levels, which can reduce the potential for condensation on windows and other surfaces. However, proper sizing and control are essential.
21. How long should an ERV run? ERV runtime depends on factors like occupancy, ventilation requirements, and climate. Some ERVs have variable speed settings to adapt to changing conditions.
22. Is 6,000 CFM a lot? 6,000 CFM is a significant airflow rate suitable for large commercial or industrial applications. It is considered a high CFM rating.
23. Is 2,000 CFM a lot? 2,000 CFM is a substantial airflow rate and is often used in larger commercial or industrial HVAC systems.
24. How many CFM do I need for a 12×12 room? The CFM needed for a 12×12 room depends on ventilation requirements, but for residential applications, it might range from 50 CFM to 100 CFM or more.
25. What is the best efficiency of an ERV? The efficiency of an ERV can vary by model and manufacturer. Look for ERVs with high Sensible Effectiveness (SRE) and Total Recovery Efficiency (TRE) ratings for better performance.
26. Are ERVs worth it? ERVs can be worth it for improving indoor air quality, managing humidity, and meeting building code requirements. Their value depends on specific needs and conditions.
27. How long do ERVs last? ERVs can last 15-20 years or more with proper maintenance. However, components may need replacement over time.
28. What if CFM is too high? If CFM is too high, it can lead to overventilation, resulting in energy waste, discomfort, and potential indoor air quality issues. Properly size and control the ERV to avoid this.
29. Can you have too much CFM? Yes, having too much CFM can lead to overventilation, energy inefficiency, and potential comfort problems. Proper sizing is crucial.
30. Is it better to have more CFM or less? It’s better to have the right amount of CFM to meet ventilation requirements without overventilating. Excessive CFM can lead to energy waste and discomfort.
31. Does ERV increase humidity in winter? ERVs transfer moisture between air streams but are designed to maintain indoor humidity levels. They do not inherently increase humidity in winter.
32. Is ERV energy efficient? ERVs can be energy-efficient because they recover heat and moisture from exhaust air, reducing the load on heating and cooling systems.
33. Why would I need an ERV? You might need an ERV to improve indoor air quality, manage humidity, meet building code requirements, or enhance energy efficiency in your HVAC system.
34. Is an ERV noisy? ERV noise levels vary by model and installation. Some ERVs are designed to operate quietly, while others may produce more noise.
35. How much does it cost to install an ERV? The cost of ERV installation varies depending on factors such as ERV size, complexity, location, and labor rates. It can range from a few thousand dollars to several thousand dollars.
36. Should I install an HRV or ERV? The choice between an HRV (Heat Recovery Ventilator) and ERV depends on your specific needs. ERVs are more suitable for managing both heat and moisture transfer, while HRVs primarily transfer heat.
37. Can you run ERV in the winter? Yes, you can run an ERV in the winter. In fact, ERVs are often more beneficial during cold weather to recover heat from exhaust air.
38. Does an ERV have a compressor? ERVs do not have compressors. They rely on passive heat and moisture transfer mechanisms.
39. Does an ERV heat the air? ERVs do not heat or cool the air. They transfer heat and moisture between incoming and outgoing air streams to maintain indoor comfort.
40. Can you add an ERV to an existing system? Yes, you can add an ERV to an existing HVAC system to improve ventilation and energy efficiency.
41. Do ERV systems have filters? Some ERV systems have built-in filters to help improve indoor air quality by capturing particles and allergens.
42. What are the different types of ERV systems? There are various types of ERV systems, including standalone units, integrated HVAC ERVs, and rooftop ERVs, each designed for specific applications.
43. Where would you use an ERV? ERVs are used in residential, commercial, and industrial buildings where improved ventilation, indoor air quality, and energy efficiency are desired.
44. How many CFM do I need for my ERV? The required CFM for your ERV depends on factors like building size, occupancy, and ventilation goals. Consult an HVAC professional for accurate sizing.
45. How often do you need to clean your ERV? ERV maintenance frequency depends on factors like usage and local conditions. Typically, ERVs should be inspected and cleaned every 3-6 months.
46. Does ERV help with mold? ERVs can help control indoor humidity levels, which may reduce the risk of mold growth. However, they are not a sole solution for mold prevention.
47. What does 4,000 CFM mean? 4,000 CFM means that the system can exchange 4,000 cubic feet of air per minute.
48. How do I convert RPM to CFM? RPM (Revolutions Per Minute) alone cannot be directly converted to CFM. CFM depends on factors like fan size, blade design, and motor efficiency.
49. Does a higher CFM mean more airflow? Yes, a higher CFM indicates a greater volume of air moved per minute, resulting in increased airflow.
50. What is the rule of thumb for CFM? The rule of thumb for CFM varies by application but is often estimated at 1 CFM per square foot of living space for residential ventilation.
51. How many CFM do I need for a 10×10 room? For a residential room, 10×10 feet in size, you might aim for around 100 CFM of ventilation.
52. How many CFM is a typical house fan? A typical house fan might have a CFM rating ranging from 2,000 to 3,000 CFM or more, depending on the fan’s size and type.
53. Why is an ERV better than HRV? ERVs are considered better than HRVs when both heat and moisture transfer are desired. They help maintain indoor humidity levels in addition to heat recovery.
54. How many CFM do I really need? The required CFM depends on the specific building, occupancy, and ventilation requirements. It’s best to consult with an HVAC professional for an accurate assessment.
55. Is 50 CFM a lot? 50 CFM may be sufficient for small spaces or applications with low ventilation needs but is not considered a high airflow rate.
56. How do you convert CFM to kW? CFM (Cubic Feet per Minute) is a measure of airflow, while kW (Kilowatts) is a measure of power. The conversion between CFM and kW depends on factors like air density and temperature, making a direct conversion challenging.