Maybe it’s happened to you. The friendly service technician is explaining what your system needs, but starts throwing out all these acronyms: “...the BTUs are too low, but per the AHRI you can get an ECM to increase the SEER.”
And you think to yourself: “Huh?”
I apologize in advance if one of our technicians starts spouting off unknown acronyms. We don’t mean to. We want you to understand your situation and how we can help improve it. But sometimes we get excited and forget that these acronyms, which are part of our everyday vocabulary, are most likely foreign to you.
So here’s a short glossary of some common acronyms that you will hear related to the HVAC industry. (That’s “Heating, Ventilating, & Air Conditioning”, just in case...)
The Air Conditioning, Heating, and Refrigeration Institute (AHRI) is a North American trade association of manufacturers of air conditioning, heating, and commercial refrigeration equipment. The organization performs political advocacy on behalf of its member industries, maintains technical standards, certifies products, shares data, conducts research, and awards scholarships. An HVAC system may have an “AHRI Rating” that qualifies it for tax rebates. This means the AHRI has tested and certified the efficiency of the system and assigned it a certification number.
The British Thermal Unit (BTU) is the standard measurement for heating capacity in heating and cooling systems. 1 BTU is the amount of energy it takes to raise the temperature of one pound of water by one degree Fahrenheit. When used for a heating system, then the BTUs of a unit are the amount of heat that it consumes or produces. When used for a cooling system, then the BTUs are the amount of heat that is removed in order to cool the air.
The electronically commutated motor (ECM) was developed to offer a greater range of operability choices, and to minimize noise in an HVAC system. ECMs are variable speed, DC motors that function using a built-in inverter and a magnet rotor, so they are able to achieve greater efficiency in air-flow systems than some kinds of AC motors and can reduce operating costs. (Although AC voltage is used to supply power to an ECM, the ECM’s internal rectifier converts the current to DC voltage). Additionally, ECMs are not prone to overheating and are also relatively low-maintenance; the use of true ball bearings reduces the need for oiling, and varied start-up speeds reduce stress on mounting hardware.
An energy efficient motor (EEM) is one which consumes less power while it is in operation as compared to a standard motor. EEMs run at a constant speed and are characterized by cost efficiency, lower operating cost, and lower demand charges and are also suitable for operations at higher ambient temperatures. EEMs run an AC power and perform better than normal motors under adverse conditions like unbalanced voltages.
The Energy Efficiency Ratio (EER) of a cooling unit is the ratio of output cooling energy in BTUs to input electrical energy in watt-hours at a given operating point. EER is generally calculated using a 95°F outside temperature, an inside temperature of 80°F and 50% relative humidity. The EER is a more realistic measurement of energy efficiency in warmer climates due to the high demand and higher cost of peak hour electricity.
The efficiency of heat pumps is rated by the SEER (see SEER below), but also by the Heating Seasonal Performance Factor (HSPF). HSPF is specifically used to measure the heating efficiency of air source heat pumps. HSPF is the heating output in BTUs during a typical heating season divided by the watt-hours of electricity used during the same period. The higher the HSPF rating of a unit, the more energy efficient it is.
The efficiency of air conditioners and heat pumps is often rated by the Seasonal Energy Efficiency Ratio (SEER). It is pronounced like one word, rather than saying each letter like the rest of the acronyms in this list. The SEER rating of a unit is the cooling output in BTUs during a typical cooling-season divided by the total electric energy input during the same period. The higher the unit’s SEER rating the more energy efficient it is. SEER rating more accurately reflects overall system efficiency on a seasonal basis whereas EER reflects the system’s energy efficiency at one specific operating condition. (See EER above.)