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  1. #1
    Join Date
    Jul 2012
    Location
    Chapel Hill
    Posts
    2

    Quotes to replace a 2nd floor unit

    I live in Chapel Hill NC, and we get warm temperatures during the summer - with the second half of July and all of August being the warmest. I have a 3.4K sq ft house built in 1998 with builder Goodman 10 SEER original units, a 2 ton unit for the first floor and a 3 ton unit for the second floor. We finished a large portion of the third floor 7 years ago and put a 2 ton Amana unit to handle that space. The second floor unit has failed and I got three quotes for replacement. I would really appreciate it if someone could look at the quotes and comment.

    Company 1
    Option 1
    XR15 - 4TTR5036E1000A (TRANE)
    XV80 - TUD2B080A9V3VA (TRANE)
    Table Coil - 4TXCB042BC3HCB

    Option 2
    XL16i - 4TTX6036E1000A (TRANE)
    XV80 - TUD2B080A9V3VA (TRANE)
    Table Coil - 4TXCB042BC3HCB

    Company 2
    Option 1
    XB13 - 4TTB3036D1000B (TRANE)
    TUD1 - TUD1B060A9361A (TRANE)
    Table Coil - 4TXCB042BC3HCB

    Option 2
    XR15 - 4TTB3036F1000A (TRANE) - Note this is what he wrote, but I can't find it
    XT80 - TUD1B060A9H31B (TRANE)
    Table Coil - 4TXCB042BC3HCB

    Company 3
    17S INF A/C PURON - 24ANB724A003
    2 Ton Aluminum Coil - CNPVP2417ALA - I believe I need a 3 ton...
    Furnace - 59TN6A060V17-14
    Control - SYSTXCCUID01-V

    Companies 1 & 2 had seemingly competent sales folks come out that spotted problems (mislabled breakers, wrong sized breakers, poor overflow designs) and answered questions. Company 3 sent someone that seems to have made some bad assumptions (size unit needed) so I'm less confident with his quote.

    Any reactions? Thanks!

  2. #2
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I just had the same system that Company 3 quoted installed in my upstairs. It's comparable to Company 1 optin 2, but a higher end HE furnace and better control. I absolutely love it. That's a 96% Effciency furnace and the humidity controls on Infinity are the best out there.

    It's possibel a load calculation was done and you only need 2 tons, especialyl wince the 3rd floor has it's own system. the 2nd floor may not need nearly as mcuh cooling as the original design. I would push harder on how he determined the size.

    A little undersized is better than oversized. Setback on AC don't save any moeny anyway. IF you set a system to 74 or 75F, you'd be amazed at how small of a system you actually need ot maintain temeprature.

    IF you ducts are sized for 3 tons and it's a builder grade unit now, a 2 ton Infinity will be dramatically quieter and more even cooling.

    But again, push them on how they determined the sizing. Since you've modified your home, the orignal size is likely not what you need now.

    But the quality of the install if more important than hte equipment. Your choosign a contractor more than a system. A good contractor will install the right system the proper way.

  3. #3
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,744
    The "Infinity" is great equipment. I'm leaning with Motoguy in that with the (new) 3rd floor system, the existing 3 ton sizing is not needed now.

    I hate the contractors that always size the new equipment with what (size) is there.

    I am surprised that the coil matches the condenser. I thought it might have to be a 2.5 or 3 ton coil.

    Also, is you go with the Carrier guy, make sure to get the tin plated coil.

  4. #4
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    Your quotes seems similar to one that a guy posted earlier this week. The units aren't exactly the same but the response is similar (http://hvac-talk.com/vbb/showthread.php?t=1123571)

    I would recommend you ask all three companies to do a manual J calc. I would definitely choose the Infinity if cost is not an issue.

    Also, for some reason the carrier guy always seems to not know what they are during.
    You can call me Sam

    It should be a crime to be a mechanical engineer in San Diego
    Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7)

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,561
    RichR, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.


    Further infractions may result in loss of posting privileges.
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  6. #6
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,213
    NC

    What size living area is second floor?

    Where will furnace be located?

    If attic location, is this in a conditioned space?

    Have you even considered a heat pump condenser?

    It should be noted that for Company 2, option number 2, the model number is not correct for an XR15 condenser. BTW, I like this option as long as condenser is the XR15. It is probably the least expensive option. It could be improved with the 60 K XV80 furnace with a true two stage thermostat.

    What size and efficiency furnace are you replacing?

    Post back.

    IMO

  7. #7
    Join Date
    Jul 2012
    Location
    Chapel Hill
    Posts
    2
    Thanks TigerDunes

    I would estimate that the second floor is approximately 1.4K sq ft. There are two stairways leading up to it and one leading to the third floor.

    The unit is located on the third floor, in unconditioned space. And it gets hot up there. Incidentally, the third floor unit is also located there. It is a 2 ton Amana unit that handles about 700 sq ft.

    I have not previously considered a heat pump condenser, but out of ignorance. None of the companies suggested it. You are correct on the item number for the XR-15 from company 2, my transcription error. Thank you for catching that. I will correct.

    The current furnace is an 80% efficient GoodMan natural gas furnace. I believe it is 75K BTUH (GMP075-3) with maximum 1200 CFM @ 0.5" ESP.

    I am interested in your comment about the XV80 improving the solution. Any data I need to chat with the sales person again?

    There were no load calcs, manual J calcs or any other calcs done to my knowledge. Is this something I could do? Alternatively, are they important to this situation?

    Thank you very much for your help. I am quite unfamiliar with HVAC...

  8. #8
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Just a thought since two units are in the same space and one zone is fairly small... if you need to replace the 3rd floor too, you could look at a single zoned system that's smaller than the two system combined. That 700sqft space is pretty small. 2 tons sounds like a lot for that. It's possible 3 tons could handle both zones.

    Or even a little more exotic would be to twin the 3rd and 2nd floor systems and set them up as 2 stage with zoning. The 2nd unit might be as small as 1.5 tons and be the "lead" unit and run most of the time. You would need backflow dampers on the supply and returns of each unit but probably wouldn't need a bypass damper.

    The major advantage is that you'd have 40-50% capaicty on low stage and partial redundancy if a sytem failed. But the larger zone could get up to maybe 3.5 tons sent to it if it had large enough ductwork.

    Just a thought.

  9. #9
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,213
    NC

    Motoguy raises an interesting idea about combining the systems of the second floor and third floor.

    You would lose some redundancy. I think it depends on how well the third floor system is performing, how much this space is actually used, and how comfortable thiscarea is both heating and cooling.

    Now back to the second floor system.

    The XT80 is Trane's offering of an 80% eff single stage furnace with a high eff blower but not var speed. The XV80 is also an 80% eff furnace but has two stages of heat and a var speed blower. Best operation of the XV80 is with a true two stg thermostat.

    Depending on your electric rate versus at gas rate, there might be some operating cost advantage with a HP condenser for most of your heating needs with the gas furnace kicking in on the colder days.

    IMO

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