The ratio between heat removed - to watt of power used - EER and SEER Cooling equipment systems used in residential and small commercial buildings often express cooling system efficiency in terms of the Energy Efficiency Ratio - EER - and/or Seasonal Energy Efficiency Ratio - SEER. For room air conditioners the commonly used efficiency ratio is the EER - Energy Efficiency Ratio For central air conditioners the commonly used ratio is SEER - Seasonal Energy Efficiency Ratio These ratings are posted on the Energy Guide Label attached to all new air conditioners. Some air conditioner manufacturers participates in the voluntary Energy Star labeling program where the Energy Star label indicates higher EER and SEER ratings. EER - Energy Efficiency Ratio EER is a measure of how efficient a cooling system operates in steady state (over time) when the outdoor temperature is at a specific level (outdoor conditions commonly used are 95 oF). the higher EER - the more energy efficient system EER can be expressed as EER = qc / P         (1) where qc = output cooling energy (Btu) P = input electrical energy consumption (watt-hours, Wh)   EER is commonly used for room air conditioners ranging 5,000 Btu per hour to 15,000 Btu per hour.

1 Btu/h = 2.931x10-4 kW = 0.0299 kpm/s = 0.252 kcal/h = 3.986x10-4 hk = 3.939x10-4 hp = 0.2163 ft lb/s In mild climates air conditioners with EER of at least 9.0 should be selected. In hotter climates air conditioners with EER over 10.should be selected. split ac units dubaiNote that EER is sometimes expressed with cooling power and electrical power consumption EERpower =  qc / P      (1b) where qc = output cooling power (Btu/h) P = input electrical power consumption (W) SEER - Seasonal Energy Efficiency Ratio SEER  - Seasonal Energy Efficiency Ratio - can be expressed as SEER = Qc / P         (2) where Qc = seasonal cooling energy (Btu) P = seasonal electrical energy consumption (Wh) SEER should be at least 10 -  there are units where SEER reach ate least 17. 1994 honda civic ac unitExample - EERpower A cooling unit operating at 1 ton/kW would have an EERpower of 12,000 Btu per hour divided by 1000 watts or 12. 1 ton window ac price chennai

This is mathematically equivalent to multiplying the COP by 3.413. Therefore a small cooling unit operating at 1 ton per kW (1000 watts) is equivalent to a COP of 3.516, or an EERpower of 12. Rule of Thumb A/C sizing question from Practice Exam I have a question regarding a question on the practice test. On page 11 there is a question that seems to conflict with the information I was looking up. The correct answer is 700 sq ft but some of the research I did supported 500 sq ft per ton. What is the correct answer? Wisconsin requires passing the National Exam and I�m doing everything I can to get ready for it within 2 weeks. A rule of thumb for air conditioning is a ton of air conditioning is needed for:700 square ft A one story house The contractor asks you how many square feet of living space there are in your house. He (or she) then tells you what size unit you need. This is called "sizing by square footage" and is the most commonly used inaccurate method of sizing.

A typical value used for air conditioners is one ton (12,000 Btu/hour) per 500 square feet (46 m2). This does not take into account differences among houses in design, construction, or energy efficiency. Table 1: Capacity rules of thumb for room air conditioners Rules of thumb for estimating air conditioner size vary by manufacturer. This example, from Carrier, includes the following suggestions for adjustments: If a room is heavily shaded, reduce capacity by 10 percent; if the room is very sunny, increase by 10 percent; and if using the unit in a kitchen, increase capacity by 4,000 Btu per hour. 100 to 150 5,000 150 to 250 6,000 250 to 300 7,000 300 to 350 8,000 350 to 400 9,000 400 to 450 10,000 450 to 550 12,000 550 to 700 14,000 700 to 1,000 18,000 Re: Rule of Thumb A/C sizing question from Practice Exam That's the rule-of-thumb we used for the Texas TREC exam. Of course, Texas is a bit warmer than some climates. IRC - M1401.3 Sizing.

Heating and cooling equipment shall be sized based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies. Yes, I'd personally choose a CMI every time over every other inspector. ~ Nick Gromicko, InterNACHI Founder Certified Master Inspector - 2010 Florida Licensed Home Inspector - HI176 Florida Licensed Mold Assessor - MRSA208 Square-One Inspection "Assurance begins here" I support the privacy of homebuyers Doesn't negate the fact that it's on the NHIE... Michael W. Gault, SC RBI 1728 A to Z Home Inspections Charleston, Dorchester & Berkeley Counties in S.C. Rules of thumb may be dumb but if I inspect a house that's a ton undersized based on that rule and we are here in hot Texas then I will call for a HVAC guy to be consulted so he can do those calcs and tell the buyer if the AC is properly sized. I won't say it is not properly sized but I will say that it should be looked into.

Re: Rule of Thumb A/C sizing question from Practice ExamHow do I select the right contractor? System sizing and proper installation are critical to energy efficiency and home comfort. It’s important to hire a qualified contractor who uses Manual J or an equivalent size calculation tool. If your contractor is certified by North American Technician Excellence (NATE), you know they’ve received special training about how to size and install your system. Note: NATE certification is not required for customers to receive rebates. Resources for finding a contractor: AC Check Trained Contractors North American Technician Excellence (NATE) How are air conditioners typically sized to meet the cooling needs for my home? Your comfort while using air conditioning depends both on reducing air temperature and removing humidity. An air conditioner should ideally run for 20 minutes or more on each cycle to cool the indoor air and to reduce humidity. Oversized air conditioners run in short inefficient cycles.

They waste energy since they must run for a few minutes at the beginning of every cycle just to cool down the indoor coil and ducts. Only then can they can cool and de-humidify your home. That original cool-down energy is wasted after the air conditioner shuts off. What is meant by “BTU” and “Ton?” An air conditioner's ability to remove heat is expressed in BTUs (British Thermal Units) per hour,or "tons" of cooling. Each ton equals 12,000 BTUs per hour, and is equal to the energy contained in a ton of ice, a term left over from the days when buildings were cooled with ice. Your air conditioner should have a ton of cooling capacity for every 400 to 1,000 square feet of floor area, depending on your home's energy efficiency and your local climate. How does insulation affect my cooling needs? A poorly shaded home with little insulation and lots of air leaks might need a ton of air conditioning for every 400 square feet of floor area. A well insulated and well-shaded home with few air leaks might only need one ton per 1000 square feet.

Contractors size air conditioning systems using computer programs or extensive hand calculations. To ensure correct sizing, ask your contractor to show you the written calculations for your home. Then have them install the smallest size air conditioner capable of cooling your home. What is the difference between EER and SEER? EER (energy efficiency ratio) is a measure of how efficiently a cooling system will operate when the outdoor temperature is at a specific level (usually 95° F). A higher EER means the system is more efficient. You can calculate kilowatts if you know the EER and the size, in tons. EER = BTUs of Cooling @ 95F / Watts used @ 95F In the case of a 10 EER, 2 ton air conditioner: 10 EER = 24,000 BTUs Out / 2,400 Watts In For the same size unit, but rated at 12 EER: 2 EER = 24,000 BTUs Out / 2,000 Watts In or 20% more efficient. If you want to calculate kilowatt-hours, just multiply the "Watts In" by the number of hours that the air conditioner is running.

SEER (seasonal energy efficiency ratio) is a measure of efficiency over an entire cooling season, as opposed to a single outdoor temperature. Residential units are almost always rated in SEER. SEER came into use as a more practical measure, since the temperature outside is not always 95º F. Also, the denominator is in watt-hours, not in watts as is the case for EER. The same relationship holds ... a higher SEER means the system is more efficient. SEER is the total amount of cooling the air conditioner will provide over the entire cooling season divided by the total number of watt-hours it will consume or: SEER = Seasonal BTUs of cooling / Seasonal watt- hours used What is the importance of EER? There are many goals and benefits of utility sponsored Efficiency Programs. Among these is education for the purpose of using energy wisely. From this a rating system to establish standards for energy consumption has been developed. One way to measure energy consumption is Seasonal Energy Efficiency Ratio (SEER).

SEER is a measure of efficiency over an entire cooling season. SEER ratings are useful in determining the amount of energy used and the amount of energy saved. Often, the unit of measure associated with SEER is kilowatt-hours (kwh). A kilowatt is 1000 watts used for 1 hour. SEER = Seasonal BTUs of cooling / Seasonal watt- hours used. There is more to energy consumption than kwh. Another measure of energy (and thus energy efficiency) is demand. Demand is the maximum amount of electricity used by an air conditioning system. This usually occurs at start up. The unit of measure associated with demand (or peak) is Energy Efficiency Ratio or EER. EER = BTUs of Cooling @ 95F / Watts used @ 95F. Almost all air conditioning units are tested under the same controlled and specific laboratory conditions to determine the EER rating. Your local sponsors, and the country as a whole, are concerned about using energy efficiently. Efficient usage occurs both in the seasonal and peak arenas. Many advocacy partners in the industry recognize SEER alone does not address demand savings.