1. 2)Look for a sheet taped to the front of the air handler (indoor unit), where the HVAC contractor has listed the performance data for the system.

  2. 3)Some manufacturers encode the SEER rating in the beginning of the model number on the data plate of the condenser. For example, the “XC21” at the beginning of the model number of the Lennox condenser shown below indicates it is rated at 21 SEER. Older systems do not do this.

  3. 4)If it is a replacement system and you have a copy of the building permit, it will usually also show the SEER of the system. In many areas, building permits can be looked up online at the county or city building department’s website, and it will often show the SEER of the system in the description of the work or the attached notes.

  4. 5)If you look for the manufacturer’s logo plate on the side or top of the condenser, it will may have a model name like “Comfortmaster 1200” or “RoyalAir 10,” which indicates the approximate—but not always exact—SEER of 12 or 10 for the system. See photos below at right for examples.

  5. 6)If you know the year of manufacture of the system, which is usually coded in the data plate of the condenser unit as the first two or second two numbers of the serial number, you can determine an approximate SEER based on the when it was made. See our blog post “What is the SEER of my old air conditioner?” for more on this approach.

  6. 7)And last, if all else fails and you really, really want to know the exact SEER of the system, jot down the model number and serial number from the data plate and call or email the manufacturer’s customer service department with the information and a request for the SEER rating of your unit.

    There is one potential flaw in several of these techniques. It has been required since 2006 that both the condenser and air handler be replaced unless it can be verified that the new half of the system that the HVAC contractor is switching out is matched by the manufacturer for performance with the remaining component. However, if part of the system was replaced by someone willing to do it without the required building permit, the SEER rating efficiency of the new part of the system may not be achieved because of the mismatch to the older part. If, for example, your outdoor unit is LENNOX and the indoor unit is GOODMAN, you definitely have a mismatched system and there is no way to determine the actual efficiency rating.

    To learn more about the requirement to match condenser and air handler, click on the link below to download a pdf info sheet from the Florida Department of Community Affairs.


While we hope you find this series of articles about home inspection helpful, they should not be considered an alternative to an actual home inspection by a local inspector. Also, construction standards vary in different parts of the country and it is possible that important issues related to your area may not be covered here.
© McGarry and Madsen Inspection


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More blog posts about heating and air conditioning:

  1. How can I find out the size of my air conditioner?

  2. How can I find out the age of my air conditioner or furnace?

  3. The coils on my heat pump are covered with ice on cold mornings. What’s wrong with it?

  4. What is the difference between the “ON” and “AUTO” settings on my thermostat?

  5. What is a “ton” of air conditioning?

  6. What is the best air conditioner for a mobile home?

  7. How do I find the right size air conditioner for my house?

  8. What is an HVAC system?

  9. What is the difference between the SEER and EER of an air conditioner?

  10. What does an ultraviolet air treatment system do?

  11. The coolant line to the outside unit of my air conditioner is frozen. What's wrong?

  12. What size air conditioner is right for my mobile home?

  13. What is the minimum SEER rating for a new air conditioner?

  14. What does the “AFUE” rating of a furnace mean?

  15. How much life is left in that air conditioner?

  16. Why is there mold around the air conditioning ducts?

  17. What is a geothermal heat pump?

  18. What is the difference between a heat pump and a cooling air conditioner?

  19. Is it alright to close the air conditioning vents in unused rooms?

  20. What is the right MERV number for my air conditioning filter?

  21. Should I move my air conditioner into the attic?

  22. My air conditioner won’t turn on What’s wrong?

  23. What are the minimum requirements for bathroom ventilation?

  24. What is an air conditioning heat recovery system?

  25. When should I switch the thermostat to “EMERGENCY HEAT” for my heat pump air conditioner?

  26. Why does the air conditioner condensate drain line need a trap in it?

  27. What is the average lifespan of an air conditioner?

  28. Should I remove an old whole house fan or keep it?

  29. What is a jump duct?

  30. Is it acceptable for an air conditioning condensate drain line to terminate under the house?

  31. What is the purpose of the vent grille over the bedroom door?

  32. Should I have a return air vent in the master bedroom?

  33. Will closing doors reduce my heating and cooling costs?

  34. How much will I save on my utility bill if I get a new higher SEER air conditioner?

  35. Which one is better for a home heating system: electric or natural gas?

  36. Why does an air conditioner condenser need to be level?

  37. Why is it bad to have a clothes dryer vent near an air conditioning condenser (outdoor unit)?

  38. When does the ban on R-22 air conditioning refrigerant take effect?

  39. Why do the lights dim when the air conditioner turns on?

  40. How can I tell if an air conditioner uses R-22 or R-410A refrigerant?

  41. Why is my air conditioner not cooling enough?

  42. What is a return air plenum for a furnace or air conditioning system?

  43. Why does it take so long to cool a house when the air conditioner has been off for a while?

  44. What are the right words to use when talking about a heating and air conditioning system?

  45. What is a ductless mini-split air conditioner?

  46. What is a FanRecycler and AirCycler?

  47. Why is my bathroom vent fan not exhausting enough air?

  48. Why has the thermostat screen gone blank?

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