There are 3 ACCA approved programs. The software manufacturers are Elite, Wrightsoft, and Nitek. The last time I talked to ACCA HVAC-calc 4.0 was not one of them. I have never used it to compare with the approved softwares. Just remember, when working with any software,
garbage in = garbage out.

I've used HVAC-Calc with good results; it agreed with Manual-J calculations by several contractors. It also will allow you to some 'what if' calculations by changing insulation levels, home orientation, etc., etc. Easy to learn, nice tool to play with.

I am a homeowner who used the HVAC-Calc software and am satisfied with the results I got.

In addition to using the software to do as-is calculations, some of the what-if calculations I did were:

Effect of installing improved windows and effect of changing the orientaion of the same windows.(not done)
Effect of adding insulation in the ceiling. (not done)

Effect of adding wall insulation in air conditioned crawlspace.(done)

Using HVAC Calc results and heat pump output at various outdoor temperatures to set the balance point.(Changed balance point set by contractor)

Determined that one large room does not get enough CFM which led to the addition of a heating run and register to that room (may have been able to accomplish the same resulting by rebalancing duct flows).

Etc...

To overcome the two month limit on the use of the software, temporarily change the date setting on the computer.

Um, demetrius - I wouldn't advise anyone to change the sys date in order to extend the period. In my neck of the woods we call that stealing. :)

C'mon, he's getting a deal anyway for his $50 anyway. We want our subs and contractors to be honest with us - let's be honest with our suppliers.

Doc

We've had good results with HVAC-Calc. Easy to use too. Plus the author will help you if you have any questions, a real big plus!

Since so many dealers guess, not a bad investment to be sure what you get will keep you comfortable efficiently for the next 15-20 years!

The responses are really appreciated. I was leaning towards this and will proceed and see what I end up with. I cannot imagine why I would need more than 60 days. I cannot wait to be done with this task!

Anyone want to turn me on to a good installer/acontractor in the Santa Cruz or San Jose area?

Thanks again
Al

Where can I get this?

http://www.hvaccomputer.com/

Just bought this yesterday and found the 2 of the 3 bids I got for heat and AC were WAY over sized in both departments. Very nice tool, anyone looking to replace an existing unit should invest the $49 for piece of mind as well as the education you will get while performing the calculation. The program is easy to use and the amount of measuring is minimal! I sent 2 emails to the author asking questions concerning sizing received answers within hours! As a computer programmer and former Automechanic, I was very pleased at the ease of use and very well written users manual/tutorial! As was mentioned it is cheap insurance and piece of mind that you are getting the proper sized system. Of the one contractor still on the short list that had over sized the AC by almost a ton.. he said he would not install the smaller unit. The contractor that under sized has not yet returned my call but I am guessing he will go up 6000 BTU.