dit

I assume IQ model is one of those in the Nordyne unbrella of companies. Correct? Sometime ago, I believe I read that what Nordyne calls a 4 ton model actually has a cooling BTU output up to around 52K.You might want to verify that with dealer.

I think you might attempt to determine if there is a reasonable payback if you elect the four ton IQ system over the five ton Amana. Any warranty difference?

IMO

Yes, the IQ drive is the Nordyne units. The 4 ton model can run up to 118% of rated capacity and they say can get up to 54K BTU. If I look at the calculations on SEER and compare a 16 SEER to a 21 SEER, there should be payback, especially if fuel prices continue to rise.

We are dealing with the same issue on a rental we own. I like the contractor, but we have halted finalizing the bid as HVAC is behind in the US, and you will be paying a premium for an IQ drive, no matter which wrapper is used (Tappan, Westinghouse, Maytag, etc.). The house is two-story with an existing 5 ton unit. The contractor said that the 4 ton IQ Drive limitation would not work well so we are opting for two 3 ton units on each floor. Even the contractor said that the IQ Drive equipment is too expensive, but he did say that for comfort he has excellent luck with the IQ Drive. I cannot see the other manufacturers not answering today's call with their own rebuttal to the IQ Drive, so my wife and I decided to wait. During the interim we paid the contractor for the load calculations, although he said we did not have to, until we decide which direction to go as there is about ten year minimum ROI on an HVAC unit.

Following this post on HVAC-Talk.com also.

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.)