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  1. #1
    Join Date
    Mar 2012
    Posts
    11

    13 SEER vs 14 & 15 SEER in 5 ton units

    We need a new condensing unit and coil. Currently have a 5 ton system. Have bids for 13 SEER Carrier , Payne & Trane systems, as well as for a 15 SEER Carrier (24ACC6).

    One company said that I would be wasting $ going with the 15 SEER unit because in 5 ton units, the efficiency gain from 13 to 14 and 15 SEER is mostly from improvements in the fan in the furnace, and since we aren't replacing the furnace, we would be paying more for no benefit. He said we'd need to go to a 16 SEER unit to see any real benefit, but he didn't recommend spending the extra $ for the 16 SEER since we may move within 5 years or so.

    Any opinions on this? Thanks in advance.

  2. #2
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,504
    Based on the increasing cost of electricity, you should get the most efficient you can afford. But it depends on where you live and the average operating hours combined with electricity costs when figuring any kind of ROI. In our area we use AC about 1000 hours a season, and based on 8 cents/kwh electricity costs we'd use $370 a year with 13 SEER 5 ton, and @$300 a year with 16 SEER 5 ton.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,087
    You would need a matching indoor unit with high efficiency motor to get anywhere near 16 SEER. The salesman told you that, right?

    The best that expensive 24ACC660 will do with your standard furnace is 14.50 SEER. Not a real big savings over 13. Maybe not in the life of the unit let alone 5 years.

  4. #4
    Join Date
    Mar 2012
    Posts
    11
    I didn't talk specifically about the 24ACC6 with the second salesman - he was the one who told me that since we weren't replacing the furnace, we wouldn't get 14 or 15 SEER efficiency even if we replaced the existing condensing unit with something like the 24ACC660. He said to get 15, we'd need to replace the whole heating/cooling system and at that point we should consider a 16 SEER system. He quoted a 16 SEER system b/c I asked him how much more it cost. He quoted a 4TTR5061E Trane XR15 two-stage a/c unit; TUD2C100B9V5V Trane XV80 variable speed two-stage heat gas furnace; & 4TXCD063BC3 Trane coil, for a total that was about 170% of the cost of just the 13 SEER condensing unit and coil. He didn't think I should go that route if I thought we might move in 5 yrs.

    The first salesman who quoted me the 15 SEER Carrier 24ACC6 unit didn't mention anything about it - he just quoted the 24ACC6 condensing unit and a Carrier CNPH evaporator. He also quoted an additional price if I wanted a filter housing that uses the 4" filters (we only have the 1" filters at the registers), whereas the second salesman said that was part of the new plenum they'd install. I wonder if this is standard part and parcel of the new plenum and the first guy thought he'd see if I'd bite since I had asked him about air filters/purifiers.

  5. #5
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Forgetting the furnace issue for a moment, the larger the system, the less efficient in almost every case. I've yet to see a 5.0-ton system that can deliver the SEER rating of the 'group' in which the manufacturer puts it. I've seen matches of equipment where a 13-SEER nominal rating will achieve something north of 14-SEER and 12.5 EER at smaller sizes but not at 5-tons.

    I think your Carrier guy has it quite right. If not replacing the furnace, go with the 13-SEER. BTB, the 13 means 13 Btu's for each Watt of electricity purchased to run the beast. So 1-Watt = 13-Btu's, 1000 Watts = 1 kW = 13,000 Btu's. So do the math. If the best you could get would be 14.5-SEER, you've gained 1500 Btu's per kW of electricity. If your cost of electricity and annual run times make that a good investment over the 5-years you intend to own the equipment, then your answer is to purchase it. But if not, then no.

    There are a few areas where the higher efficiency equipment can actually, mathematically, pay off for a single home. But for the most part, higher is efficiency either a method of decreasing group loads for the power company, where thousands of homes are considered as a group and power reductions are totaled, for homeowners who want to do their part at reducing power consumption and therefore being a little 'greener'. The final need is where the higher efficiency is obtain through the use of smaller pumping capacity, such as with 2-stage and/or modulating equipment. This leads to superior comfort in many areas of the country. Hope this helps a little. SO.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  6. #6
    Join Date
    Mar 2012
    Posts
    11
    Thanks. I think one of the real issues for me, then, is that if the first salesman quoted a 15 SEER unit even though there was little to no chance I'd get anything better than the 13 SEER unit without upgrading the blower, then either he didn't know, or worse, he did but didn't mention it. Either way, I think the second salesman would be a better choice even though he is a few hundred dollars more expensive for the same product.

  7. #7
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,504
    Way too many "salesmen" quote the efficiency off the brochures the manufacturers hand out and these quoted efficiencies are the "highest" this model will attain. Sadly this efficiency is usually only with a certain air handler matched to the smallest model made. Once you get in the largest size unit, then this efficiency will or could be much less. You need to know the actual AHRI matched efficiency of what you are being quoted.

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