Originally Posted By: lfranklin
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Thanks Blaine
See if I am getting this right. SEER has to to with the efficeny of the unit and nothing to do with size of the unit.
Thanks Blaine
See if I am getting this right. SEER has to to with the efficeny of the unit and nothing to do with size of the unit.
Originally Posted By: kluce
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That is correct. Ton=size SEER=efficiency
Nobody uses BTU's for Air Conditioning around here, and I would think most places don't use btu ether. So when checking size, most people use tons for Air Conditioning and BTU's for furnaces. I don't even report the efficiency of the A.C. unit.
Originally Posted By: Blaine Wiley
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Larry, you got it.
Kevin, you got it.
Nobody uses BTU for A/C, but just in case you get that inquisitive client, ya just gotsta know how many BTU in a ton. 
Originally Posted By: rpalac
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Very often I find people get hung up on BTU’s, and Tonnage. They are one in the same and just a different form of measurement. Yes, 12,000 BTU’s (British Thermal Unit) = 1 Ton both heating and cooling. Very often as part of the serial number but not always. Carrier for instance has numbers that don’t relate. I just call the manufacture to get better data. However that was when I was in the business of replacing units.
The SEER Rating (which is the measured efficiency rating- Seasonal Energy Efficiency ratio- as some pointed out) has nothing to do with the ability of cooling, but does tell how much energy the unit consumes to do the job. I agree that the seer rating is over exploited as you have proven. The cost to recover the initial expense is over a long period of time.
One of the most important factors with regard to sizing A/C load is removing moisture from the air, and proper feed sizing and returns to circulate the air. If the unit is over sized the A/C will meet temp but never get a chance to pull the moisture from the air. There fore constantly cycling...costing a lot more money to the consumer and not feeling very cool to the skin due to the moisture left in the air. The moisture is what holds the heat. That's why when it is humid out side you feel so hot, and when it is dry in the winter you feel so cold. This is the key to comfort in sizing an A/C system. Using ball park numbers is okay but only for our purposes of round figures. You better believe there is a lot more to the subject of properly sizing and A/C system than ball parking. One of the achieved comport calculations is done by using wet bulb and dry bulb calculations and the humidity content. To properly size an A/C unit it is best left to an HVAC engineer, we can only rough guess that it is close or correct. I use to do calculations for this and the bottom line is does the unit run and are they happy.
As an inspector I have to say that it is more important for me to see that there is nothing restricting the air flow such as blocked filters or obstructions with stored items. I also make sure that the inside and outside coils are visually clean. The outside coil very often in clogged with mud splash from rain, soil from construction or lint because the dryer vent is to close. These are problems that hinder the units performance. If it is winter I make a note that the buyer should have the unit prepared for summer by a reputable HVAC firm and that it was unable to be properly tested due to the current temperatures.
I hope this is somewhat helpful.