HVAC School - For Techs, By Techs
EER in the Field - Short #231
· Summarized
Key takeaways
- EER and SEER are crucial metrics for evaluating HVAC system efficiency, with EER providing a snapshot and SEER offering a seasonal average.
- Measuring EER requires understanding BTU production and converting it against wattage, necessitating accurate temperature and airflow readings.
- Field conditions significantly influence the calculated EER, making it essential to understand the test conditions behind EER and SEER ratings.
- Using modern tools like MeasureQuick can simplify the process of obtaining accurate EER measurements in the field.
- Understanding related metrics like COP and HSPF is important for a comprehensive assessment of HVAC system performance.
Summary
Understanding EER and SEER
In this episode, Bryan delves into the differences between Energy Efficiency Ratio (EER) and Seasonal Energy Efficiency Ratio (SEER). He explains that while SEER accounts for seasonal performance averaged over cooling seasons, EER is a snapshot of the system's performance under specific conditions. Bryan clarifies that EER is calculated as the ratio of cooling capacity (in BTUs) to electrical power input (in watts), emphasizing that understanding these metrics is essential for assessing HVAC equipment efficiency.
Calculating EER in the Field
The podcast discusses the practical approach to measuring EER in the field. Bryan explains the need to determine BTU production, which involves measuring delta enthalpy, airflow (CFM), and wattage consumption. He provides insights on using tools like MeasureQuick to simplify this process. Bryan highlights the importance of accurate wet bulb temperature readings and CFM measurements, detailing methodologies such as the TrueFlow grid and blower charts to ensure precise calculations.
Impact of Operating Conditions
Bryan discusses how varying field conditions, such as indoor/outdoor temperatures and humidity levels, can significantly affect EER calculations. He emphasizes the importance of knowing the specific conditions under which EER and SEER ratings were obtained, particularly with revised standards for EER2 and SEER2, which provide more realistic testing conditions. The episode explains how these factors influence the overall efficiency ratings and the operation of HVAC systems.
Understanding COP, HSPF, and Measurement Challenges
In addition to EER and SEER, Bryan highlights the Coefficient of Performance (COP) and Heating Seasonal Performance Factor (HSPF) metrics. He explains that COP is essentially a direct ratio of watts out to watts in and discusses how HSPF applies to heat pumps. The podcast also touches on the complexity of measuring wattage in modern HVAC equipment, especially with ECM motors and inverter-driven systems, where traditional volt x amp calculations may not suffice.
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Show notes
In this short podcast episode, Bryan talks about EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratio) and how to calculate EER in the field.
EER and SEER are ratings that we often see on equipment (as are SEER2 and EER2) based on a ratio of an output to an input. Whereas coefficient of performance (COP) is a direct ratio of watts out to watts in, EER and SEER account for BTUs and watts. EER and SEER indicate the cooling capacity (in BTUs) we get from the watts we put in.
The ratio changes based on field conditions, and EER2 and SEER2 have more realistic test conditions than EER and SEER (the static pressure for systems rated below 65,000 BTUs per hour was 0.1"wc for EER and SEER, and it is now 0.5"wc for EER2 and SEER2, which is much closer to average field conditions).
To determine EER, you have to figure out BTU production and stack it against your wattage. You'll need to know your delta enthalpy (delta H), multiply it by the CFM, and then multiply the product of those by 4.5 to get your BTU output. A calculator on apps like measureQuick can help you find out your delta H, but you'll need a proper wet-bulb temperature before you can do that. You can determine CFM with a TrueFlow grid or manufacturer's blower charts.
Finding watts can be a challenge with ECMs and inverter-driven systems; it's not as simple as volts x amps, and you will need a meter that can measure power factor and take readings from the condenser fan, compressor, and blower motor. That wattage becomes the number you divide into BTUs to get the EER. SEER is averaged over a season, HSPF is for heating instead of cooling, and you can convert the BTUs to watts (by multiplying by 3.41) and determine the ratio of watts out to watts in.
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