Sorry, I get so much to reply to I don't usually get back to these posts. You need to e-mail me because I may never see your replies & questions. If my memory is correct, around 35 years ago occassionally the compressors had higher BTUH ratings than the condensing units. Laxer49 I just checked your page & my birthday is on Dec 8th, too, I will be 73. Those 10-SEER condensers' used to do real well. If the E-Coil has a leak it should be replaced anyway. Laxer49, If it were me, I would put a New half ton larger BTUH rated Coil in there with a TXV refrigerant control. If you can get a real good deal on a new 10-SEER with that combination & the correct tightly sealed ducts & airflow it should cool okay in the hottest weather. If you want the most cost-effective payback I would do all I could to reduce the radiant & other heat gain as the insulation will also reduce the heating bills. The Installation is the most important thing, it has to be done right! Read & learn allyou can. Funkeruski, I suppose they replaced the evaporator with a matching TXV controlled coil? Everything has to be performed just right & even then if it is real hot & the indoor load is also heavy it may not equal the old unit which would have a larger BTUH capacity compressor on that 4-ton condenser. Those high SEER tests are performed under rather light load conditions. The SEER of a system is determined by multiplying the steady state energy efficiency ratio (EER) measured at conditions of 82°F Outdoor Temperature, 80°F Dry Bulb and 67°F Wet Bulb (near 50%RH) indoor entering air temperature by the Part Load Factor (PLF) of the system. (The PLF is supplied by the government.) IMO, they ought to be tested at 95 or 100-F outdoor temperature. Which SEER do you think will perform better at 100-F plus ambient temperatures, the one with the larger capacity compressor or the smaller one? You could slow the blower CFM down to keep the suction pressure & E-Coil temp somewhat lower, but that also drops sensible capacity some. At 82-F outdoors, the 15 should do real well against the 10. Just my viewpoint. udarrell _ 2007 Here is a link that might be useful: udarrell.com

I have owned this Maytag 23 SEER IQ Drive equipment from Nordyne (both a 3 ton & a 2 ton unit)since April 2009. I replaced two old, inefficient systems in their entirety. I paid top dollar for this high efficiency equipment and boy was I taken! Lots of service calls (more in 1 year than in the 11 years I owned the older units); high humidity inside the house (a new problem that started with the install of this equipment); noisy fans that wake me up when the units shut down at night; no improvement in energy efficiency at all (I have to keep the house 4 degrees cooler than with the old equipment to keep from sweating, due to the high humidity); equipment is sensitive to power fluctuations (computer brain flips out every time there is a switching transient from the power company and must be reset); and the list just goes on and on. I would NOT recommend purchasing this product. A Trane 2 Stage system would likely be a much better investment (note: I have never owned Trane equipment and I don't know anyone who works for Trane - it just happens to be the alternative I investigated before deciding to buy the IQ Drive.)

If it should happen to have a Dehumidifier TH combo, you would have to set the Dehumid stat to a higher setting. If the AC is oversized for the temperatures where high humidity is a problem, then you would need to look at ways to reduce the infiltration of humidity, or reduce (Vent,etc.) the interior sources. I am thinking that when you slide the button to cool or AC the controls are miswired, & the AC will run until you slide the botton to off. Do NOT short cycle the AC, leave it off for 5 minutes before restarting it! Some have a differential Stat, where it cycles on at say a setting of 77-F & off at your setting of say 74-F. It would not have a differential as wide as yours is performing. A two or three degree Temp diferential will save energy. When the unit is off during the three degree differential, use other fans to move air over the occupant areas. This can be a real money saver especially with oversized AC & Heat Pump equipment systems. udarrell _ 2007 Here is a link that might be useful: udarrell.com

The contractor probably does not want to recalculate the load calculation because he may find a mistake and then you will use it against him. The calculation is probably correct. I am a little skeptical about the duct loss. What he has seems low. I would want an explanation on how that number was generated. There could be an additional 0.5 ton of loss that is missing just in duct losses. I am also concerned that this is the first time he has installed this equipment and in 5 trips he has not been able to solve the problem. When you talk to American Standard, tell them the contractor is having problems getting the equipment to work correctly. Installation issues are not their problem. Let them know you have a load calculation and the unit size is matched to the calculation, but the equipment does not seem to working as per the spec sheet. Tell them it is a new installation and with new duct work. Hopefully they will work with you and send someone to inspect the system.