I just had three contractors bid on putting in central AC. All three contractors came up with very different bids with different sizes and details, and I am asking your help figuring them out as I am pretty confused.
Background info: my house is a 1200 sq ft, one story, 1962 brick ranch near Denver, CO. There is also a full finished basement. The 125,000 BTU Janitrol forced-air gas furnace is newer, replaced in 1993. There is already a large, Goodman U-49 coil sized for up to a 4-ton condenser (or so I'm told) installed above the furnace (coil is an R22), but no refrigerant lines (20 foot run to side of house). I can't tell what year the coil is from but seems likely that it would have been installed in 1993 with the furnace--before I owned the home. The forced air ducts that are in the basement ceiling are metal ducts and the tin-over-joist space method to carry return air. There is no insulation at all in the exterior walls, which I will probably try to have corrected asap with blown-in insulation, and there is 6" of cellulose fill in the attic. The windows are brand new (2006), low-e, double-pane vinyl windows.
Now to the bids:
#1) Will install a 14 SEER 2.5 ton Goodman model 140301 with a 2 year labor warranty, using existing coil.
#2) Will install a 13 SEER 3-ton (he recommends going a bit large due to the age of my home, though he would be willing to install a 2.5 ton 130301A also) Goodman model 130361, again using my existing coil. His labor warranty is only one year. Also, he says my furnace blower won't fully utilize a 14 SEER Goodman model--something about the blower not being variable speed?--and I'll just get 13 performance anyway because I will run it like the single speed 13 SEER unit.
#3) Wants to rip out the existing coil and install a 2-ton R410a Lennox Elite XC13 (13 SEER) for much, MUCH more money than #1 or #2, whose bids are almost exactly equal. He has a five year labor warranty but only if we either sign a yearly maintenance agreement with him or maintain it well ourselves.
All three say they did manual J worksheets on the house and then compensated for their experience in the area. All three have excellent references. #2 lives in a house of similar vintage and construction to mine. I've been working with #2 the most so far, but mostly because the electrician he recommended impressed me the most. (The electrical bids were done separately as I needed a service box/panel upgrade to pass code.)
My First Question: The 14 SEER unit from #1 is somewhat attractive to me, but not if #2 is right that I would really need to upgrade my furnace blower (and thermostat?) to make it work. Who's right?
My Second Question: I am also getting conflicting information about whether I can convert the existing coil and new lineset for R22 to R410a if I should need to replace the AC after 10-15 years. #2 claims that he could just put in TXV valves (I didn't quite catch the exact part?) to keep the existing coil in use and his lineset installation would be able to take the higher pressure of the 410a (after it is flushed). #1 says his lineset will be ok for reuse but the coil will need to be changed out. #3 says everything would need to be ripped out as all line and coil sizes are matched to the refrigerant. Everyone agrees that I would need a new condenser/compressor unit to change refrigerants.
Who's right? Is #2 full of it? Is #3 overselling me?
One more note: #1 and #2 both say they have no philosophical reason for recommending a R22 system, just that they can put my existing coil to use. They'll each do a R410a system, but it would be more--closer to, but still significantly below, the bid of #3. #2 said he could do it a little cheaper by making the existing coil work with a new 410a system if I wanted to go that route. They both say that with a good installation like theirs, I shouldn't have coolant leaks so the expected price rise for the phaseout of R22 will likely not affect me until enough years pass (15+) that I am likely to be considering replacing the AC condenser anyway. (Actually even #3 also said that I would be unlikely to be affected for 10-15 years if I had him put in an R22 unit right now.)
Thanks so much for your help. I tried to be as detailed as possible, sorry for the length.