I know this is not the season for air conditioning.  But here in Texas, it got up to 112 deg for several days.  I had electric bills that were nearly $500 for 4 months and my AC ran 24 hours a day.   I do not want to live through that again.  My home and air conditioning unit were built/ purchased in 2004.  I feel that the unit is undersized but most contractors have disagreed because they are going by some EPA recommendation.  The unit is a 3 ton Carrier, I think 8 seer.  The home is 1987 sq ft, two story.  Here is my quesiton:  How can I determine how much electricity will be save if I upgrade to a 4 ton 13 seer unit?Welcome to the community. I remember seeing news reports last summer about the truly smoking hot weather down south. Since you have SEER, (Seasonal Energy Efficiency Rating), ratios for both old and new units, a rough estimate is fairly easy.  The new larger unit will hopefully not have to run 24/7 like your current one does. Based strictly on output per watt of power in and assuming all other conditions are the same, the new A/C will use about 8/13 as much electricity. 

This is about 38% less energy use. Hopefully next summer won’t be as hot either! I hope this helps, In November 2010 we replaced a 4 ton Lennox 1992 8 seer with a 4 ton XR 15 Trane 16 seer (including compressor, air handler and UV lights. Under air we have 2045 SQ feet (two story) Cost installed was about $4600.00 After installation the KW usage dropped so dramatically the Electric company sent out a meter reader to check  :-) how does outside ac unit workIn Florida the hottest months are usually July-August-SeptemberJuly -August 2010 temps were an average of 90 degrees,  we used 3353 KW hours that month.the outside ac unit is not turning onIn comparison the July -August 2011  KW hours usage at average temps of 93 degrees was 1842 KW hours. small ac unit for house

My last bill received was $132.00 with budget billing as opposed to the average of  $300.00 we were paying prior to installing the new unit. Made a big difference, you will notice it within 30-60 days. I hope this helps.  THank you for the info.  My high kilowatt usage was Aug 4-Sep 5 at 4712.8 kwh. If I am calculating correctly, 38% less kilowatts, that would be around 2929 kwh.  So that would be good.  You gave me even more good information with the numbers on the kw usage.  From Aug 4- Sep 5 we used 4712.8 kwh and Sep 6-Oct 5 3859 kwh.  If I can reduce usage like you did to 1842 kwh, I would be happy. Newf - is the calculation you are using 8/13 referring to the 8 seer vs 13 seer systems?  So if I get a 15 seer the calculation would be 8/15 ?  Thanks in advance for the info.Mathematically, comparing pure ratios the numbers work out that way. Going from 8 to 15 you would use 8/15 as much power (53%), saving 47% compared to what you used to use. While your mileage may vary due to real world factors like fan motor run-time, changes in weather from one year to the next, etc. the savings are still substantial. 

floridalife57's real world examples show the energy savings. I should add that anywhere you can improve on insulation will also reap rewards. Programmable thermostats can also help when there are periods of time the home is unoccupied. Hello floridalife57 and welcome to the Community! We are glad to have you join the forum. Thanks for the real world information on your energy savings. Let’s keep the meter readers busy. Please keep us updated on your projects and feel free to join in helping others. Hi Newf, Is it better to replace the AC Unit during the fall and winter months? If so, what are the advantages of doing so?  The only advantage I can think of is that in the "off" season you MAY be able to get a price break. While the same people that install A/C units generally also do furnaces, there is no hurry to install an A/C unit now in much of the country.  As a result, the install can be timed when crews are not busy.  Add to that the occasional clearance sales from manufacturers at this time of year and there is at least the potential of saving some money.

Also a cost issue, if you need to replace your furnace then adding in a new A/C unit at the same time can result in some savings. Hi Newf - I am still planning this project and I am down to deciding on heat pump or electric furnace to go with my new AC.  Can you tell me which one uses less electricity?  Heat pump or electric furnace?< 1 2 3 > Originally Posted by lifelongMOgal You likely have an 8 - 10 SEER system. Going to the minimum standard of 13 SEER would be a 30 - 62% increase in efficiency. Of course it's hard to say how much that would save you but generally the warmer the climate, the longer the AC runs, and the larger % of your power bill comes from the AC. Generally 70% of your power bill is for HVAC system. So if your power bill is $100/month then about $70 is from your HVAC system. Let's just say you chose a 13 SEER system and you previously had a 10 SEER system. You would expect about a $21/month savings. Over the course of 10 years using 6 months out of the year as your cooling season you'd save $1,260.

Doesn't seem like much, huh? But what about the other scenario? You have an 8 SEER system (or less) and you go to the minimum 13 SEER system. Your power bill is $200/month. Your savings, all things being equal, would be $5,208 for the 10 year period. I'm assuming you're in MO and your cooling season is probably a little longer than 6 months but those were just for the examples I provided. Originally Posted by mscrash It can't hurt to have your coils and fan blades cleaned and to have a checkup for things like voltage drop on your contactor and the integrity of your capacitor tested. Older units because of lack of efficiency standards and general manufacturing practices were built like tanks and tend to be made with more material than today's units. Those are signs of a lack of proper airflow. Believe it or not the temperature drop actually increases as the volume of air going over the evap coil decreases at the same time overall capacity decreases. You can have the coils cleaned or you can clean them yourself if you're somewhat handy.

I wouldn't recommend you cleaning the fan blades yourself unless you're comfortable tearing the system apart and putting it back together correctly. It also could be a failing fan motor which a technician can evaluate. I would take the other's suggestions and start looking now. Start saving money for the replacement and if you can wait until you're in between seasons and the HVAC company is hurting for work. You'll also want to get lots of bids and use guidelines like this to make your evaluation: 7,748 posts, read 14,728,356 times 1,289 posts, read 2,165,956 times 433 posts, read 884,540 times A new A/C unit and the insulation job cost approx the same, There is no way in any portion of the world or underworld that insulation would cost as much as a new AC system!! You should be looking at $400-$600 max. UNLESS you are trying to get the latest and greatest Icynene insulation, (which you can STILL do it yourself! just google "do it yourself spray insulation")

The other poster is right. Just get a few friends and have them help you blow some insulation in. Give them the opportunity to drink the RIGHT fluids (ie water, Gatorade, etc ) before hand and the right Fluids after they are done. (then also give them the option to try other fluids when they have rehydrated! ) 14 posts, read 31,033 times 107,588 posts, read 39,577,952 times All I would say is that your condensing unit may be an 81' model. This doesn't mean that the heart of it ..the compressor hasn't been replaced 6 times. Fans go bad and are replaced. If the coils and tubing are good, then other than efficiency concerns, let her be. Now granted, today especially if a compressor goes out an entire new cond. unit is generally recommended. Depending on the service companies prices you might opt either way. BTW, if he really added a "little" freon and it really needed it...did he fix the leak? Did he charge extra for this little squirt of freon? No need to answer..... just questions to ponder.