Regardless of the acrimonious comments, BX is typical of the guys in the field. As I win small concessions from him and others, I realize what I am fighting. If I met with him on a regular basis, I would probably cherish his acquaintance. I am not the typical HVAC service guy, so I am not wedded to previous ways of doing business. Although I serviced several generations of equipment, I only spent about 20% of my time with HVAC and refrigeration as a service guy. I performed service for many years, but only spent a small portion of time with HVAC. I did not believe in many of the NEW techniques for installation, until I understood why they are necessary. If I had the money or desire for continuing education, I am sure that I could learn new tricks. What I do not like are old-timers that just donÂt want to keep up with new design techniques. Texas has attempted to force continuing education of contractors. This is a hindrance to the small guy, and large companies do not typically train the rank and file worker. The real problem is the availability of junk courses that can be taken that do nothing for training or learning of new information. Furthermore the requirement is only for licensed contractors. It does not include the workers. When a major company has multiple trucks, I would imagine the information gleaned is not passed to the workers. Since management is a small subset of the workforce, the training of workers does not exist in Texas. As long as they have a CFC certificate, this is all that is needed. As to duct installation, training is on-the-job. The typical worker is non-English speaking; non green card entitled foreigners. This group of people is NEVER trained for more than is necessary to do a minimal job. Furthermore when they are knowledgeable, they are too old to do the job quickly, so they are replaced. I am sure this is not the norm in all geographic areas, but in the southern areas this is typical. The hot climate areas are where design is so important for proper operation of equipment, but is done by minimal trained workers. When you see a legal worker, he is probably at the same level as the other group discussed. Last summer was proof of the need for trained installation workers. The typical cooling bill for my area was double of previous years. Complaints of bills higher than mortgage payments were common. One story that emphasizes this issue was on TV and about an owner of a 3000 sqft house that had $900+ monthly electric bills, which were more than his mortgage payments. If I sound too authoritative, sometimes it is needed, to wake up the general population. We tend to ignore problems until faced with them ourselves. Then when we look for help; it just isnÂt there.

Since this isn't a typical replacement but rather a completely new installation with new ductwork, a load calculation is necessary. A new system sized and designed based on guesswork will do you no favors down the road. It's possible that one has been done, although often times they are not done, especially if it is a straightforward changeout and the previous size equipment "did the job." You should ask for the heating and cooling loads, in btu/h, from Manual J (method for load calculations). If a 4 ton is more appropriate, even if it's a 2-stage unit, a 5 ton system will be less efficient, cost more upfront, and likely dehumidify worse (due to running shorter cycles).

Hi, guys. I just want to give you an update on my central AC project. I finally went with the contractor that gave the most detailed estimation and also did the heat load calculation to figure out that I needed a 4T AC. I decided to go with the Carrier 24ACA3-48-A003 and CNPVP4821 for a good compromise between price and efficiency. I would not be able to recoup the extra few hundred dollars that I paid up front for the higher SEER units. The final price that I paid is $4885 (I got 5% off for paying with check instead of credit card). This also includes a nice TP-PAC18 Edge programmable thermostat. The contractor did the installation today. He put in new lines (3/8 for liquid and 7/8 for vapor) on the outside of the house going from ground up to the attic. He also had to install a couple of extra things due to the vertical seperation is more than 20'. The job is pretty nice and clean. This installation also includes Carrier extended warranty for 10yrs, part and labor, on everything. Pretty nice. I guess now I have to wait till the first hot day to see how well this work. Thx for everyone's help.

I have to agree with the two posts before this. With the numbers that your are providing you would typically need the 2 1/2 ton to size for both the latent and sensible sides of the load. To find your sensible capacity you must ask the manufacture for their expanded ratings of their condensing unit. Then you must pay close attention using your wet bulb and indoor dry bulb temperatures. This information will give you your sensible ratio. Both loads will have their percent requirements that need to meet or exceed the loads required from the original Manual J report that you conducted. For Manual J, Manual D, Manual S, heat load calculations, and energy code compliance reports please visit our websites. THIS IS NOT AN ADVERTISEMENT!!! We only want to offer additional sources for assistance. Our goal is to help our industry toward more energy efficient building practices. Good luck with your building project! http://www.larsentech.org http://www.myspace.com/manualj Here is a link that might be useful: http://www.larsentech.org