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  1. #1

    Confused Home Owner Question

    I am a confused home owner - HVAC is not my field, and for good reason. I would be grateful for any advice from experience here...

    I have a 2700sq/ft single story home with a split system - A/C compressor outside, gas furnace/coils in the attic - in the Upstate South Carolina area. I have two 20x25 returns, 22 supply vents, 16" return lines, 8" supply lines (with a lot of Y's that need to be fixed). Most of the house does have 12' ceilings and I have a ton of windows/french doors.

    I currently have a 16 year old Goodman 10 SEER 4 ton A/C with a 5 ton system in the attic. I have only been here about 4 years and have dropped about $1,000 keeping it running and am being told it needs to go by two different contractors. The unit has never been able to really do a good job of cooling things down in the Summer, though the heat works great.

    I have decided I am going to be here for a very long time and want to do this right - not just a band-aid until I can sell. That said, I have had 5 companies give me quotes.

    Trane - Nice units but spec for spec I am getting about $2K higher estimates on Trane than Lennox and I am unable to see a justification. Warranty on both as well as other performance specifications seem the same on the models I have compared. Perhaps the rep didnt know enough about the units? In any case, I have not been sold on Trane.

    Lennox is my next choice. I also looked at Goodman and Rheem, but Lennox and Trane really seemed to be head and shoulders above those. Maybe just better sales reps...?

    In the Lennox line what is being recommened (partly due to my wanting the best long term investment) is the XC21 series matched with the SLP98V furnace. Also getting the air purifier, the iComfort Touch controller and some duct work modifications.

    So my question: I have 2 guys saying I need a 5 ton unit, 2 guys saying I need a 4 ton unit and 1 "whatever you want". The 5 ton units are much lower SEER ratings, but aside from a piece of paper I have no real world idea what is better. I tend to be one of those "if a little is good, more is better and too much is just about perfect" kind of guys. I am not sure if that works in HVAC though. Is too big a bad thing? WIll it shorten the life of components, not dehumidify enough, not be energy efficient?

    Any thoughts?

    Thanks for any advice!

  2. #2
    Join Date
    Dec 2010
    Down by the river
    did any contractors perform load calculations and evaluate your ductwork?
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  3. #3
    Join Date
    May 2004
    Smaller is better. Get the load calc or energy audit. Figure out what your highest heat gain items are. From there you can make a better choice as you might be able to reduce some heat gain.

    Bigger is better works in reverse on HVAC. You want longer run times to make you feel comfortable.

    Your spending a lot of money so take your time and do your homework.

  4. #4
    Join Date
    Jan 2004
    If your current 4 ton keeps the house cool when its working right. Then you don't need a 5 ton. Might not even need a 4 ton.
    Contractor locator map


    How many times must one fix something before it is fixed?

  5. #5
    Each contractor walked the attic and looked at the ductwork. In fact, I was fairly surprised that 4 of the 5 gave almost the identical answers on the ductwork (two endcaps needed to be added for static pressure, 4 Y's needed to be re-worked).

    In regards to calculations, they each wanted to know the dimensions of the returns (25x20), that there were two of them, that there was 16" return ducting, the square footage of the home, the number of supply vents and a general idea of heat sources like my entertainment system/computers and generally how many windows there were. Some contractors were more specific than others. Beyond this information nothing else was asked. Not being familiar with the calculation you guys are mentioning I am not sure if this is all the variables needed or if there is something more that they left out.

    And yes - this is a serious expense. From a homeowner's point of view it is completely frustrating because there is no real way to tell things like if a unit has been installed correctly (which everyone here states is the most critical thing) and this isnt something you can simply return. Now I know how some of my clients feel when I start going into server and firewall specs...

    Thanks again

  6. #6
    Join Date
    Jul 2001
    Where do you live? I'm in Anderson, I might can give some advise.


  7. #7
    Taylors chris --AT-- scfriends, dot, com Thanks!

  8. #8
    Join Date
    Jul 2010
    Have you considered putting this off until fall or spring? Cooling season's ending soon and you may want to spend some time asking questions and doing some homework on AC, furnaces and duct systems.

    If you have any knowledge about your house regarding its insulation values, I'd suggest running your own room by room Manual J just to get a ballpark figure. Although most folks say that its one of the things a contractor should do many wont do it until after a contract is signed (which boggles me). Doing a proper one can take some time. Also from what I hear it doesnt necessarily mean that you'll get the results.

  9. #9
    Join Date
    Feb 2010
    Ontario Canada
    Both sizing and quality of installation are important. Get the proper heat loss/heat gain calculations done as well as a duct layout. Do your homework on your contractor. Ask for and follow up with references. Be comfortable with your homework and you will be comfortable with the purchase.
    Never give up; Never surrender!

  10. #10
    In regards to putting this off, that is unfortunately not a viable option. My existing system has had several issues lately and a couple different service people have told me it is runnign very high head pressures and did not expect it to last. I am at the mercy of their integrity, but I tend to believe them. Since I travel heavily for work and just happen to be home for a couple weeks I wanted to get this taken care of.

    I have spent all day yesterday/today researching the companies I have received quotes from (BBB issues, references that each left with me, online searches, etc.) to get a feel for who is qualified and people feel good about recommending. Luckily one company stands above all the others based on the feedback I have received...and they were the lowest quote.

    I have spent a fair number of hours reading through this site and really appreciate all the information you guys have posted over the years. At least I can not talk with the contractor and ask intelligent questions and not feel like an idiot.

    Oh, and yes, from what I have calculated, 4 ton is perfectly fine for my needs and a full 2 SEER higher rated than the 5 ton version of the same A/C.

  11. #11
    Join Date
    Sep 2009
    Arnold mo
    I would recommend that you first determine if there are simple things you can do to improve your homes ability to withstand wind, heat and cold. A home that has a good "thermal envelope" will require a smaller system than a house that has major air leakage & insulation issues. The more you put into that, the less you will have to put into the other. There is a person on this site that lives in Houston in a house with 4000 sq.ft. and he only has a 2 ton a/c. Eskimos lived in a home made of snow with an outside temp of minus 50 and keep the inside of their snow home at plus 20 using body heat alone!
    We need to add a new manual () calc to the hvac equation. First a Manual H (for (H)ome improvement) and then a Manual J; in that order.
    I would also suggest you find a contractor who is able to determine if your ductwork is adequate for whatever sized system you will need. Central air systems are not window units...ductwork to these systems is like veins & arteries are to a heart.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............

  12. #12
    Join Date
    May 2004
    Quote Originally Posted by UPstateChris View Post
    Taylors chris --AT-- scfriends, dot, com Thanks!
    Are we hiding from BOTS

    The only other thing is a 10 year parts and labor warranty. See if you can get one for a good price. Pricing is not allow here, but it is something to think about. The one you want is a manufacture warranty, so even if your contractor moves to Texas. The manufacture will cover the parts and labor.
    Most new units come with a 10 parts warranty, so this just covers labor.

  13. #13
    Join Date
    Aug 2011
    Ductwork definitely seems like an issue, as well as heat load; and maybe I'm wrong but I thought general rule of thumb was 400 sqft/ton of cooling with 8' ceilings. You have 12' ceilings and 2700 sqft. hmmmmmmmm. 2700/400=6.75 figure in the high ceilings and high number of windows, french doors etc. ... next step from a 5 ton is 7.5; but I think one key thing is being over looked here. HIGH HEAD PRESSURE!!! What does that usually mean?? could explain why it cools but not very well. Anyone thinking what I'm thinking?

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