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  1. #1
    Join Date
    Jul 2008
    Location
    Longview, Tx
    Posts
    17

    ARI-Based Operating Cost Comparison of Lennox XP15, XP16 and XP19

    OK, I'm a bit confused (and maybe dazed, too...) by what my comparison seems to be telling me, so I'd appreciate anyone who can find any mistakes.

    For background, I've been worrying about our heat pump for a couple of years, and looked at some manufacturer's sites and talked to some different local companies about two years ago. I like what I can understand about the Carrier technology, but neither of the Carrier dealers impressed me (at that time - things may have changed).

    The dealer that did seem to the most professional handles American Standard and Lennox. So, I looked at the Lennox models on the www.ARIdirectory.org web site. After playing around a bit, I sort of figured out how to use it and looked up the Lennox combinations for the XP15, XP16 and XP19 models in a 30,000 to 42,000 Btu/hr range (2.5-3.5 tons, right?). My current unit is 3 tons and in the absence of any better information I figured that whatever compressor/coil combinations showed up in the 2.5-3.5 ton range would probably include whatever size the dealer would calculate.

    The tables from the site show an estimated cooling cost and an estimated heating cost. It's not clear to me exactly what those are, so I assumed they were annual costs. In general, as cooling costs went down, the heating costs went up (and vice-versa) - which I guess means that you can 'tune' the compressor and coil combinations to give better performance in cooling, but that hurts the heating performance and vice-versa.

    Given that we're in an electric-only subdivision (in east Texas - go figure!) I couldn't consider dual fuel units. It seemed that the lowest total estimated cost (cooling plus heating) that gave the required cooling and heating capacities would be the best unit - at least on operating costs, so I calculated that for the XP15, XP16 and XP19 models. The results surprised me.

    Here is the information and ARI's estimated costs for several of the lowest total operating cost combinations for the XP15, XP16 and XP19 models:

    ...........................Heat...........Heat
    Cool......................High...........Low Est$ Est$ Est$
    BTU.....EER...SEER...BTU..HSPF..BTU Cool Heat Total

    36000 12.20 15.20 31000 9.00 19400 203 459 662 XP15
    36000 12.20 15.20 31000 9.00 19400 203 459 662
    35800 11.70 14.50 31400 8.70 20800 212 474 686
    35800 11.70 14.50 31400 8.70 20800 212 474 686
    34800 11.50 14.00 31400 8.70 19700 213 474 687
    34600 11.20 13.70 31400 8.70 20800 217 474 691
    34600 11.20 13.70 31400 8.70 20800 217 474 691


    37400 12.20 16.70 33400 8.50 20000 192 567 759 XP16
    35600 11.70 16.00 33200 8.20 19900 191 587 778
    35600 11.70 16.00 33200 8.20 19900 191 587 778
    35600 11.70 15.70 33000 8.20 19700 195 587 782
    36800 12.20 16.20 32800 8.20 19700 195 587 782
    35600 11.70 15.70 33000 8.20 19700 195 587 782
    36800 12.20 16.20 32800 8.20 19700 195 587 782
    35600 11.20 14.70 33600 8.20 20400 208 587 795
    35200 11.50 15.50 33000 8.00 19900 195 602 797


    36000 12.70 18.60 32200 9.30 19500 166 444 610 XP19
    36000 12.70 18.60 32200 9.30 19500 166 444 610
    34600 12.00 17.75 32200 9.05 19700 167 456 623
    34600 12.00 17.75 32200 9.05 19700 167 456 623
    35600 12.50 17.60 32000 9.10 19500 173 454 627
    35600 12.50 17.60 32000 9.10 19500 173 454 627
    34400 12.00 17.00 32000 8.90 19600 174 464 638
    34400 12.00 17.00 32000 8.90 19600 174 464 638
    33800 11.05 15.15 32400 8.35 20000 191 494 685
    34000 11.10 15.25 32400 8.35 20000 191 494 685
    34400 11.20 15.35 32400 8.35 20200 192 494 686


    As I said, if the estimated heating and cooling costs from ARI are in dollars per year, the results seem to show that the XP19 would save only about $50 per year over the XP15 - and that the XP16 would cost almost $100 more than the XP15.

    Now I realize that these differences would change if my electric rates are different from what ARI assumed - but that wouldn't change the relative rankings of the models. A more significant effect could be caused if we here have twice as many cooling days and half as many heating days as ARI used. But, even with that the XP16 was still more expensive than the XP15 - and the advantage of the XP19 over the XP15 increased only to about $80 (from $50).

    My big question is - am I missing something here?

    My second question - does anyone know what the "IsHSVTC" column in the ARI listing means? One combination for each model has a 'Yes' in the column, but I don't know if that's a good, bad or relatively unimportant thing...

    Thanks for any help on all of this!

  2. #2
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    You have to decide if you want 2-stage cooling or go with a single stage condenser.

    You will read responses like "2 stage is sold for comfort and not cost savings" and "2 stage allows for better humidity removal the longer it runs on 1st stage".

    I believe that you want the highest EER possible, 12 or better, regardless of SEER. You should also get a full 3 tons (36,000 btu's) of cooling. Some of those XP19 combos are weak on cooling btu's and EER. Once those fancy, high SEER, dual compressor / dual stage units kick into 2nd stage in your hot summers, you'll want all the btu's that you can get for the lowest operating cost (EER).

    Good luck.

  3. #3
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    HSVTC = Highest Sales Volume Tested Combination.

  4. #4
    Join Date
    Jul 2008
    Location
    Longview, Tx
    Posts
    17
    Ryan - thanks for the info - HSVTC isn't an abbreviation I run across every day!

    Gary - thanks for pointing out that the XP15 is the only single-stage unit in the bunch. In terms of needing two stages for humidity management, I guess that would be optional in our case since the house with its one-stage unit is currently livable.

    On the XP15, would a variable-speed air handler be good insurance against potential humidity problems?

    I'm still amazed that the XP15 has a lower estimated operating cost than the XP16 and that the XP19 (which has got to cost a bundle more, I'd think) has an estimated operating cost that's only about $50 more than the XP15.

    Is there something wrong in the way ARI estimates these costs, or do they just not reflect what the costs are for operating 'real world' units?

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,330
    A VS blower will remove more moisure then a standard.

    2 stage is for comfort. Even in Hot Texas, you have more days that first stage can provide cooling and better humidity removal then a single, at a lower operating cost. And possibly set your stat a degree or 2 higher. And reduce operating cost further.

    Contractors that install 2 stage systems know this from their customers that they have install them for.

    Ask any contractor that installs both types of systems, which systems they get the most praise about.

    The National operating estimate they use is of course inaccurate. It is not applied for one set areas rates, or conditions.

    I drive a car that gives good handling performance, and MPG. Its not real comfortable for long distance trips.
    If I did long distance trips on a regular basis, I'd buy a car that is more comfortable, even if it got a few less MPG.
    But for the small amount of driving I do in my Personal vehicle, comfort was not of high importance.

    How important comfort is to you, is one of the factors you should concider in you choice of which unit to get.
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