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  1. #1
    Join Date
    Mar 2008
    Posts
    10

    Confused A/C out - need to decide on new system NOW!! Opinions please

    Hello all, I've been researching new HVAC system for one of the zones of my home in Dallas, TX. Good thing, as my AC went out today, so will likely replace unless it's a cheap fix. Current equipment is 3.5 ton, 15 years old, 10 SEER, R22.

    Did a load calc for the area and it came out at just over 3 tons (39,581 BTU heat gain). Please look at systems proposed and let me know which you would recommend, given that system 2 is about 15% more than system 1. Could also go with a comparable Rheem system for about the same as system 1.

    Both systems would include same install details including all new duct work, but use existing line set.

    Liked both contractors, and both come highly recommended, so would be comfortable with either. Thanks in advance for your thoughts, as I'll likely need to pull the trigger on this in the next couple of days.

    System 1 - 3.5 Ton
    WESTINGHOUSE 3.5 TON 14.5 SEER SYSTEM (41,500 BTU COOLING)
    - CONDENSER M# FS4BE042K
    - HIGH EFFICIENCY COILS, M#C5BHX42CB
    - 96,000 BTU FURNACE, M# FG6RA07216B
    MANUFACTURER'S WARRANTIES: 10 YEAR ALL PARTS, PLUS WESTINGHOUSE "QUALITY PLEDGE"WESTINGHOUSE 3.5 TON 14.5 SEER SYSTEM (41,500 BTU COOLING)

    System 2 - 3 Ton
    Carrier two speed condensers model # 24ANA748A003.
    Carrier variable speed two stage 80 % afue furnaces model # 58CVA090-1-16.
    Carrier tin plated indoor evaporator coils model # CSPHP4812ATA.
    Carrier Infinity controls model # SYSTXCCUID01-B.
    Carrier EZ-FLEX merv ten rated filters model # EXPXXUNV0016.
    Warranty:
    Ten year parts and labor extended, ten year compressor part and twenty year heat exchanger part warranty.

  2. #2
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    did the contractors do a load calc?
    did you account for RH?
    did you show your calc to contractors, so they could catch errors?
    have you been comfortable when old system was running?
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  3. #3
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,584
    Quote Originally Posted by rhb4321 View Post
    Hello all, I've been researching new HVAC system for one of the zones of my home in Dallas, TX. Good thing, as my AC went out today, so will likely replace unless it's a cheap fix. Current equipment is 3.5 ton, 15 years old, 10 SEER, R22.

    Did a load calc for the area and it came out at just over 3 tons (39,581 BTU heat gain). Please look at systems proposed and let me know which you would recommend, given that system 2 is about 15% more than system 1. Could also go with a comparable Rheem system for about the same as system 1.

    Both systems would include same install details including all new duct work, but use existing line set.

    Liked both contractors, and both come highly recommended, so would be comfortable with either. Thanks in advance for your thoughts, as I'll likely need to pull the trigger on this in the next couple of days.

    System 1 - 3.5 Ton
    WESTINGHOUSE 3.5 TON 14.5 SEER SYSTEM (41,500 BTU COOLING)
    - CONDENSER M# FS4BE042K
    - HIGH EFFICIENCY COILS, M#C5BHX42CB
    - 96,000 BTU FURNACE, M# FG6RA07216B
    MANUFACTURER'S WARRANTIES: 10 YEAR ALL PARTS, PLUS WESTINGHOUSE "QUALITY PLEDGE"WESTINGHOUSE 3.5 TON 14.5 SEER SYSTEM (41,500 BTU COOLING)

    System 2 - 3 Ton
    Carrier two speed condensers model # 24ANA748A003.
    Carrier variable speed two stage 80 % afue furnaces model # 58CVA090-1-16.
    Carrier tin plated indoor evaporator coils model # CSPHP4812ATA.
    Carrier Infinity controls model # SYSTXCCUID01-B.
    Carrier EZ-FLEX merv ten rated filters model # EXPXXUNV0016.
    Warranty:
    Ten year parts and labor extended, ten year compressor part and twenty year heat exchanger part warranty.
    \
    System 2 = Is a 4.0 ton NOT 3.0 ton.
    Get the Carrier and hurry before your 1000.00 rebate expires on June 30,2008.
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

  4. #4
    Join Date
    Feb 2003
    Location
    garland, texas
    Posts
    671
    Westinghouse in my oponion would be considered a builders model or second tier product. The weather is a little cooler do a little more research. Highly recommended referrals usually mean he has best price or he's a nice guy they don't automatically translate to top quality.
    Last edited by nvr2old; 06-18-2008 at 08:24 AM.

  5. #5
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,032
    Don't oversize the equipment. Looks like you need a three ton and nothing larger by your calculations.

    You oversize and you will have equipment short cycling with bad humidity control.
    Beware of advice given by some guy on the Internet.

  6. #6
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,559
    Go with the 3 1/2 ton anything. As far as oversized, it would be so marginal, it wouldn't effect anything. Not only that. I'm 3 hours south of you and its hitting 100 degrees regularly. Your old one was a 3 1/2 ton and your load calc came out somewhere in between. You would have short cycling and possible humidity issues if you went to a 5 ton, probably even a 4. Doubtfully a 3 1/2. Talk to your contractor, they will guide you along.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,082
    The Carrier is a 4 ton 2 stage 50/100 compressor. So in first stage it should have roughly 2.4 ton capacity.

    How did your old 3.5 ton handle the cooling load over the years. Did it struggle sometimes, or did it cycle on and off on your normal hot days.

    If it stuggled, he the Carrier 2 stage. If it cycled, the Westinghouse 3.5 ton.
    Contractor locator map

    How-to-apply-for-Professional

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

  8. #8
    Join Date
    Mar 2008
    Posts
    10
    I actually did the load calc using HVAC-Calc and the pre-loaded settings for Dallas, TX, then had the contractors validate it. As to comfort, it struggles a bit during the hottest days, but I'm convinced that is as much my spaghetti duct work as it is the unit. When I do this, I'm going to re-locate the unit to make more direct duct runs; that's included in the pricing.

    Any concerns over the reciprocating compressor in the Carrier?

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,082
    No, its a good compressor.

    So your increasing to a 4 ton then.

    What did the load calc say for sensible, and latent load.
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    How many times must one fix something before it is fixed?

  10. #10
    Join Date
    Mar 2008
    Posts
    10
    Here's the HVAC-Calc design conditions and summary report for the zone in question:

    Design Conditions: Dallas
    Indoor: Outdoor:
    Summer temperature: 72 Summer temperature: 105
    Winter temperature: 70 Winter temperature: 20
    Relative humidity: 55 Summer grains of moisture: 93
    Daily temperature range: High
    Sensible Gain: 36,222
    Latent Gain: 3,359
    Total Gain: 39,581

    I did not use any "safety margin", just went with the Dallas settings from CALC.

    Think the Carrier is a better system, but worried about over/under size with it, as the Infinity doesn't have 1/2 tons......

    Final wild card thought: what about the Westinghouse IQ? This is the most lived in part of the house, so might consider spending more to ensure comfort.....

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,082
    The IQ, may be a better choice for you. It should mod down to what you need under most of the load conditions you'll have.
    Contractor locator map

    How-to-apply-for-Professional

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

  12. #12
    Join Date
    May 2008
    Location
    North Texas
    Posts
    105
    The traditional load in Dallas has been a design of 100*F. 105 is high as a design temperature unless it is a year like 1980.

    You show a sensible of 36,222. This is a load, and not an equipment selection. When you match sensible to sensible, you may find that a 4 ton equipment is closer, if 105* is the design point. That's why the question of were you content with your 3.5 ton.

    When the outside temp goes over 95, then you have to derate the outside unit. When the inside is 72 and not 80 then you have to adjust the evaporator. Minor adjustments to be sure, but Manual J is only a beginning point for equipment sizing.

  13. #13
    Join Date
    Mar 2008
    Posts
    10
    Oops, posted the one where I DID use a "safety factor". The one using CALC design conditions was a "bit" lower, but still in the "which way do I go" range.

    I am interested in some of the comments regarding the Westinghouse system, as AHRI lists Carrier as the weaker EER and Btuh of the two. I realize that the controls are different, but couldn't I get the same dehumidifying effect with a variable speed furnace and Honeywell VisionPro stat? Still trying to learn what's what......

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