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  1. #1
    Join Date
    Apr 2013
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    90

    Help navigating central AC quotes

    Current System: A 15+ year old 3.5 ton unit with a SEER 8 rating - ducts appear to be uninsulated and run through the attic. Simple setup with a 50' main supply duct that runs a straight line down the middle of the house and 10 smaller ducts running from it to vents. Home is a ranch style house with 2500 sq ft. Located in southern CT. Current system is obviously inefficient and needs to run 100% of the time during hot weather but does cool and dehumidify well.


    COMPANY 1
    Quote includes:
    Trane outdoor AC unit
    Condenser leveling pad
    Trane Hyperion indoor air handler
    Watertight safety drain pan and platform
    Honeywell thermostat

    Scope of work:
    Remove current air handler and condensing unit and discard per EPA requirments
    Place new air handler in attic with water tight pan/wood platform
    Wrap existing supply and return distribution system with R8 duct wrap
    Install new R8 flexible duct from existing distribution line to ceiling registers
    Place outdoor condensing unit on a approved pad
    Replace refrigeration piping/electrical wiring
    Complete drain piping.

    Efficiency Options:

    1. XB 14 SEER OPTION - $X
    Indoor unit: GAM5A0C42M31
    Outdoor unit: 4TTB4042E1
    Combined SEER = 15

    2. Xli 15 SEER OPTION - $X
    Indoor unit: AM7A0C48H41
    Outdoor unit: 4TTX5042A1
    Combined SEER = 16

    3. Xli 16 SEER OPTION - $X
    Indoor unit: AM7A0C48H41
    Outdoor unit: 4TTX6048G1
    Combined SEER = 17

    Honestly all of these quotes seems really high. There's nothing particularly difficult about this change out. Guy is claiming it will take two guys 4 days to complete for EIGHT man days and that this is where the majority of the cost is occurred. Guy was pushing option number 2. Honestly I know very little about HVAC.


    COMPANY 2
    Another guy came in and said he wanted to install a 4ton Rheem with a SEER 13 rating. Project would include changing air handler, AC, and lines.
    Interestingly he said the main supply duct was internally insulated and he was just going to wrap that duct without disassembling it and replace the smaller feeder ducts with new insulated flexible ducts.

    His cost for the job $X

    My concerns: He said 2 days maximum. He is the only one to mention the "internally insulated duct". Is Rheem a lesser brand? I'm assuming if wants to use a SEER 13 system he's scrapping the bottom of the quality barrel? I was referred by my neighbor and they are perfectly happy but I've called some of their "guys" in the past and they definitely value $ over quality. Should I be afraid of this quote??


    I only put the $ amount because they are drastically different but the work isn't apples to apples. Any thoughts or opinions would be appreciated.
    Last edited by BaldLoonie; 04-16-2013 at 12:58 PM. Reason: removed pricing

  2. #2
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Last edited by jpsmith1cm; 04-16-2013 at 07:48 PM. Reason: Non AOP Pro member

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,456
    NO actual prices allowed!

    You can explain the relative position of the bids, but list 'NO' pricing numbers!

  4. #4
    Join Date
    Apr 2013
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    90
    Ok....quote 1 is a little over twice quote 2.

  5. #5
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,456
    Current System: A 15+ year old 3.5 ton unit with a SEER 8 rating - ducts appear to be uninsulated and run through the attic. Simple setup with a 50' main supply duct that runs a straight line down the middle of the house and 10 smaller ducts running from it to vents.

    Home is a ranch style house with 2500 sq ft. Located in southern CT.
    Current system is obviously inefficient and needs to run 100% of the time during hot weather but does cool and dehumidify well
    .
    New Haven CT 2.5% summer design is 84-F dry bulb, 73-F wet bulb or 59% relative humidity.

    At 84-F outdoors & 75-F indoors, that's only a 9 degree differential; therefore it 'appears' the A/C could be way oversized with ridiculously poor duct system, both from a standpoint of sizing & lack of insulation, causing long runtimes removing the heat of condensation & not lowering the sensible RM/TH temp enough.

    There could very well be a number of other reasons why the old 3.5-Ton didn't cool effectively; compromised refrigerant system during installation & more...NEVER go by your old systems performance, - unless every aspect of its "delivered performance" was tested & verified!

    You need a heat-gain calc performed with duct sizing in proportion to the Btuh required to each room. Do enough retro-work on your home to bring the heat-gain calc down to 'perhaps' 3-Ton; airflow & everything will work better, with a much higher % of the Btuh heat being removed from the rooms.

    Going up to a 4-Ton unit may compound your problems & your utility costs; NOT an idea I would entertain


    Get that new duct system optimally insulated; get the return ducting properly sized along with extra large RA filter sizing for optimal airflow efficiency...

  6. #6
    Join Date
    Apr 2013
    Posts
    90
    Quote Originally Posted by udarrell View Post
    .
    New Haven CT 2.5% summer design is 84-F dry bulb, 73-F wet bulb or 59% relative humidity.

    At 84-F outdoors & 75-F indoors, that's only a 9 degree differential; therefore it 'appears' the A/C could be way oversized with ridiculously poor duct system, both from a standpoint of sizing & lack of insulation, causing long runtimes removing the heat of condensation & not lowering the sensible RM/TH temp enough.

    There could very well be a number of other reasons why the old 3.5-Ton didn't cool effectively; compromised refrigerant system during installation & more...NEVER go by your old systems performance, - unless every aspect of its "delivered performance" was tested & verified!

    You need a heat-gain calc performed with duct sizing in proportion to the Btuh required to each room. Do enough retro-work on your home to bring the heat-gain calc down to 'perhaps' 3-Ton; airflow & everything will work better, with a much higher % of the Btuh heat being removed from the rooms.

    Going up to a 4-Ton unit may compound your problems & your utility costs; NOT an idea I would entertain


    Get that new duct system optimally insulated; get the return ducting properly sized along with extra large RA filter sizing for optimal airflow efficiency...
    Thanks for the input. Current system is a 3.5 ton handler with a 1.5 ton A/C outside - totally mismatched. The current DOES cool and dehumidify well enough although it runs 24/7 to do so and my electric bill goes up $500 per month in the summer. Company one did a bunch of measurements and calculations to arrive at 3.5 tons.....guy had his laptop out crunching numbers. I think company 1 would do everything to the letter of the law. I think the second company will "get 'er done" but make compromises.

    The real question is will those compromises really have a significant impact when we're talking half the money?

    Have three more companies coming out to give quotes - can't wait to hear their take.

    I really appreciate your input - thank you!

  7. #7
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,456
    Quote Originally Posted by idmd View Post
    Thanks for the input. Current system is a 3.5 ton handler with a 1.5 ton A/C outside - totally mismatched. The current DOES cool and dehumidify well enough although it runs 24/7 to do so and my electric bill goes up $500 per month in the summer. Company one did a bunch of measurements and calculations to arrive at 3.5 tons.....guy had his laptop out crunching numbers. I think company 1 would do everything to the letter of the law. I think the second company will "get 'er done" but make compromises.

    The real question is will those compromises really have a significant impact when we're talking half the money?

    Have three more companies coming out to give quotes - can't wait to hear their take.

    I really appreciate your input - thank you!
    Well, the new reality that it is a 1.5-Ton condenser with a 3.5-Ton air handler sheds a new light on the situation.
    The evaporator coil may not be 3.5-Ton, it may be a 2-Ton indoor Evap-coil.(?)

    The air handler may have needed to be larger to easily handle the heating airflow.

    It would appear that your home & duct system are NOT very energy efficient; which results in a large utility bill.

    If you could tell us where the windows are in relation to your homes orientation; their size & type plus the insulation factors; walls & attic; someone could run a mockup heat-gain calc that would just be a ballpark view of the heat-gain load factors.
    Maybe the laptop guy is doing a load calc...?

    The inefficiencies appear to be apart from the 1.5-Ton condenser; however, its Btuh performance would also need checking.

  8. #8
    Join Date
    Apr 2013
    Posts
    90
    Company one came out to calculate a heat gained/lost. Measured all the rooms and input all the variables and because of one room furthest from the air handler on the southern side of the house with large windows on 3 sides it bumped the requirement from 3.5 ton to 5 ton - he said that room alone (maybe 12x12') requires nearly a ton of cooling itself. Obviously 5 ton would add a significant amount $. He said if he changed the parameters from cooling the house to 75F on a 95F day to 77F on a 95F day the 4 ton works. He said I need to add another air return to do this and that the room in questions would likely be a few degrees warmer. As it is with the current system there could be as much as an 8-10F difference with just that room. I'm thinking after sealing/insulating and upgrading that should be more like 2-3F on the warmest days?
    This stuff is really outside my knowledge - what do the experts think?

  9. #9
    Join Date
    Apr 2013
    Posts
    90
    BTW....company 1 is the company that wants to disassemble sections of the main supply duct to seal and insulate all 4 sides. His feeling is there will be heat penetration on the underside and sweating will be a problem. He showed me an area in my dinning room ceiling that I never notices where the plaster is starting to buckle and sure enough the main supply duct runs above that very area (roof is new with no leaks). Also, he said the quoted price includes adding some runs to some of the larger rooms on the southern part of the house that currently only have one run and need two.

  10. #10
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,788
    Electric bill going up in Summer is not always the result of the air conditioner. I had a homeowner who thought the same thing, but it turned out he ran a 2 HP swimming pool pump 24/7 in the summer. The pool pump was the main cause of the high bills.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  11. #11
    Join Date
    Apr 2013
    Posts
    90
    No pool...the only difference between summer and winter is heating vs cooling. The old system ran 24/7 when it was hot.

  12. #12
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
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    Your first step should be to have an energy audit done to see how leaky your home is and how well insulated. The home is the primary defense against the weather, and that is the place to start. The better the home's envelope, the less HVAC size you need.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  13. #13
    Join Date
    Apr 2013
    Posts
    90
    We are half way through an energy audit but it stopped when the AC didn't work. Was going to have them back after fixing but now we're going down the road of replacement.

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