No matter what make sure you get a Manual J done. I spent 2 months researching after my AC unit needed replacing. I interviewed 5 (I think) different HVAC companies in this area. All have been mentioned on this board. The one I chose did the Manual J, answered all my questions, and was very good about it. He ended up bringing his whole crew to do the install to get it done as fast as possible.
The 4 I didn't choose wanted to replace the unit with the same size, or bigger unit. This is a big problem because the original unit was over sized and caused it to loose efficiency.
Check out these two forums
Residential HVAC - HVAC-Talk: Heating, Air & Refrigeration Discussion
Heat Pumps and Electric Heating - DoItYourself.com Community Forums
and this maybe helpful for comparing fuel costs.
WarmAir.net - Fuel Cost Comparisons
Okay time to boast my technical knowledge since some have doubts...
Is the system Manual J designed, and for what parameter? Did they ask for such info as window specs., floorplans, home orientation, building materials, or dimensions? Did he/she give the the load calculation report? Because salesman are good at sniffing out that you want a bigger unit or a smaller one even though it's not needed. A Basic 13 SEER Unit must operate for 30 mins before it even achieves its 13 SEER rating, did you know that? If they undersized your unit you will only achieve inefficiency and that will lead to more serious issues like a sick house.
Manual S reports should follow a load calc. and will designate the proper equipment size. Did they provide a report of this to ensure that they selected the proper size?
So let's say they did give all that to you, now after the replacement did they replace the entire trunkline (including all sheet metal supplying all the air for the system) to compensate for the lesser amount of air moving through the system? If they did replace ductwork did they use the manual D method? If not then you have a poorly designed duct system that will not perform correctly with the smaller unit they just installed and you will lose efficiency. As we know that = $.
Okay so lets say they did all of the above. Now you have a brand new system supposedly designed and installed correctly, now where's the proof? Do you have all of the paper work to prove it? Its your house and its the only way to know for sure.
Oh, so they did give you all the paperwork including all the reports? Well did you get a second opinion on the hard copy evidence you have to prove that everything was done correctly?
These are the things consumers need to know. Salesman are salesman because they are good at what they do. Your only protection is education and knowledge of whatever the project is you have them out there for. I agree with you on the research part and you did a good job, but don't be so sure the one you used was doing it correctly either unless you know for sure how to do it yourself, or you have researched it.
Engineers don't waste time at a desk writing designs and books on how to properly do stuff for no reason.
