Page 1 of 2 12 LastLast
Results 1 to 13 of 24
  1. #1
    Join Date
    Mar 2020
    Posts
    10
    Post Likes

    Having my Furnace and AC replaced, request advice

    Gentlemen & Ladies of HVAC-Talk,

    I have a 25+? year old Lennox system which is still running believe it or not, but decided I should have it replaced on my own terms before it gives up the ghost.

    Wondering if the capacity of the AC system quoted by local contractors makes sense for my house. I am not sure the capacity of the AC as it doesn't say on the unit. But I was quoted for a 13 or 16 SEER 3 ton replacement. No details were provided on the quotes of what type of evaporator coil would be used.

    The furnace is 100k BTU 80% and I am looking at upgrading to a 96% two stage variable at 100k BTU.

    Here are the stats on the house:
    Zip: 84116 (SLC Utah, elevation 4500'. Winters a little below freezing, summers plenty of 100 deg days)

    Split level house, 2300 SQ Ft.
    2 x 4 walls with mostly 40 year old insulation

    Main above ground level 1650 sq ft.
    3 4x6 N Facing windows Double Pane
    3 4x5 N Facing windows Double Pane
    2 6 x 8 S Facing windowed sliding doors
    2 6 x S Facing double pane windows
    1 4x4 S Facing single pane window

    Blinds installed in all windows for summer

    Finished basement with concrete walls 650 SQ FT

    3 4x3 N Facing double pane windows
    2 5x3 S Facing single pane windows

    The attic is blow in insulation of all the types (- asbestos.) Looking to add more venting to it to cool it down in the summer time.

    The only part of the house that isn't ventilated is the garage. There is nothing that splits the upstairs and downstairs as far as load control in the summer unless I close the vents in the basement.

    Here are pictures of the current units. He said he would do a better job on the line set for the AC (not sure how, but it doesn't look great dragging on the ground.) Unfortunately someone scratched off the sticker that showed when the furnace was first installed but I believe it was in the mid - early 90s.

    **Can't post photos yet, will add them when I get 7 posts**

    Any advice appreciated. Also if you think it's a dumb idea to replace before it goes out I'm all ears, but I was told my current units are a ticking time bomb when I bought the house four years ago. The AC compressor has been blowing it's start motor capacitor every other year or so.

    Of the two contractors that quoted the job one uses Day & Night and the other is Rheem. Both come highly recommended from friends who have used them.

    TIA

  2. #2
    Join Date
    Jan 2010
    Location
    Sea to Sky
    Posts
    3,673
    Post Likes
    For starters who suggested you need a larger furnace....80,000 btu output to 96,000 Btu output?

    You need a load calculation done to know the correct size furnace and AC for your house.

    Sent from my SM-G965W using Tapatalk

  3. #3
    Join Date
    Mar 2020
    Posts
    10
    Post Likes
    Thread Starter
    Quote Originally Posted by BALloyd View Post
    For starters who suggested you need a larger furnace....80,000 btu output to 96,000 Btu output?
    Both contractors who came out so far.

  4. #4
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,992
    Post Likes
    Quote Originally Posted by theschlubb View Post
    Both contractors who came out so far.
    Confidence in the mechanical contractors is low given that they wish to increase furnace OUTput.

    I would NOT select Rheem Nor Day & Night

    pursue Trane, Bryant or ___
    ___ Bryant = higher end Carrier derivative than Day & Night


    SLC UTAH 1980 built
    ~360 Sq Feet Windows

    2,300 Sq Ft : Heat Loss is likely < 56,000 BTU/HR at 14'F

    R-11 WALLS
    R-30 CEILING

    ~ 0.45 A.C.H. Natural ___
    ________ Any infiltration information from a Blower Door Test

    3 or 4-Ton ?

    My Gmail address : racingdan11

    HDD65
    5,466 Total

    Jan
    1079
    839
    637
    437

    200
    48
    2
    2
    62
    365
    735
    1060

    Dec

    CDD65
    Total 1262

    Jan
    0
    0
    0
    4
    51

    Jun
    200

    461
    399
    137
    10
    0
    0
    Dec.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  5. #5
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,992
    Post Likes

    BUILDING THERMAL ENVELOPE

    Glass and Wall Areas
    Attached Images Attached Images  
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  6. #6
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    40,773
    Post Likes
    Everyone has their own opinion on equipment. Key is best possible installation and correct sizing. My employer has sold Rheem since the 1980s. I've had it in my house, Sis & niece still do. Sis got a test 34" 90 in 1993. New motor & ignitor in 27 years. ICP is very much like Carrier these days. Same parts, same factory. In some cases only difference is color of cabinet.

  7. #7
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    27,291
    Post Likes
    The installing contractor is more important then the name on the boxes!

    First have a load calculation performed. Manual "J" too determine what size equipment you actually need, your contractors are guessing.

  8. #8
    Join Date
    Jan 2014
    Location
    New England
    Posts
    6,794
    Post Likes
    The compressor ( if legible ) has information on the tonnage of your existing system. Certainly a load calculation goes a long way to see what you need as already mentioned. Especially if you made upgrades to your residence over the years, more insulation or better windows etc.

    Make sure to register your system as manufacturers warranty decreases significantly if never registered.

    If your considering the 16 SEER system, make sure they install a AHRI matched system, as at the very least, the system may qualify for rebates and the Federal Tax Credits. You don’t go by the outdoor unit ratings for SEER ratings alone, it’s the combination of indoor selection along with the outdoor section that gives you your SEER and EER ratings. Those numbers are not real world numbers but gives the ratings anyway. My thinking is if your paying for a 16 SEER system, you should get that rating, reason for a AHRI number.

    Even if you go with a 13+ SEER A/C unit the high efficiency furnace ( 96% ) they propose should qualify for the Federal Tax Credits and even the blower motor if advanced main air circulating fan. Also should qualify for rebates your state of local gas utility company may offer.

    https://www.google.com/url?sa=t&rct=...iQc0GVu13UMfK_

    https://www.energystar.gov/about/fed...ty_tax_credits

  9. #9
    Join Date
    Mar 2020
    Posts
    10
    Post Likes
    Thread Starter
    Thanks for all of the replies! Long day ahead of me and then I can properly review everything.

    At Dan.. what’s an extra 40,000BTU between friends?? I knew 96k sounded like overkill but good lord..

  10. #10
    Join Date
    Jan 2014
    Location
    New England
    Posts
    6,794
    Post Likes
    Quote Originally Posted by theschlubb View Post
    Thanks for all of the replies! Long day ahead of me and then I can properly review everything.

    ..
    Ask the bidding Contractors what a high altitude kit for each brand model furnace consists of and any adjustment as at 4500’ elevation, I would think one would be required?

    If you wanted to follow the manufacturers specifications for the OD unit, the manufacturers want the minimum and maximum overcurrent protection ( breaker or fuses ) to be within a certain size. Being 25+ years old system and depending on tonnage of old unit ( pops circuit breaker yearly with start kit ) and those older units used more amprege to run, than the newer more energy efficient systems nowadays. Your existing breaker may be oversized for the newer systems, even if they are the same tonnage.

    You can get a idea of how much less amprege your new system will use as you mention your existing system still operates. Have them take the amprege reading of the compressor, ( separate of the OD fan motor ) OD fan motor and ID fan motor, then compare to the new systems ratings once the changeout is completed at somewhat similar OD and ID temperatures and run times.
    Last edited by Bazooka Joey; 03-17-2020 at 11:07 AM.

  11. #11
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,992
    Post Likes
    Quote Originally Posted by theschlubb View Post

    Thanks for all of the replies!
    Long day ahead of me and then I can properly review everything.

    At Dan.. what’s an extra 40,000BTU between friends??
    I knew 96k sounded like overkill but good lord..
    ATTACHMENTS

    4 photos from OP: theschlubb

    Should we presume that the existing 3-Ton was adequate over the long term?
    Attached Images Attached Images     
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  12. #12
    Join Date
    Sep 2002
    Posts
    27,399
    Post Likes
    I am far away, not familiar with your area, nor your home - but off the top of my well experienced head I would guesstimate that 100K BTU of heating is close to double what you are likely to require. Certainly 25% too much.

    What you need done FIRST is accurate heat loss & gain measurement and calculation by someone who knows how.

    Without that you are just guessing and there is no benefit to you in guessing. And there is certainly no need to guess - the ability to be very accurate is readily available.

    PHM
    -----------------


    Quote Originally Posted by theschlubb View Post
    Gentlemen & Ladies of HVAC-Talk,

    I have a 25+? year old Lennox system which is still running believe it or not, but decided I should have it replaced on my own terms before it gives up the ghost.

    Wondering if the capacity of the AC system quoted by local contractors makes sense for my house. I am not sure the capacity of the AC as it doesn't say on the unit. But I was quoted for a 13 or 16 SEER 3 ton replacement. No details were provided on the quotes of what type of evaporator coil would be used.

    The furnace is 100k BTU 80% and I am looking at upgrading to a 96% two stage variable at 100k BTU.

    Here are the stats on the house:
    Zip: 84116 (SLC Utah, elevation 4500'. Winters a little below freezing, summers plenty of 100 deg days)

    Split level house, 2300 SQ Ft.
    2 x 4 walls with mostly 40 year old insulation

    Main above ground level 1650 sq ft.
    3 4x6 N Facing windows Double Pane
    3 4x5 N Facing windows Double Pane
    2 6 x 8 S Facing windowed sliding doors
    2 6 x S Facing double pane windows
    1 4x4 S Facing single pane window

    Blinds installed in all windows for summer

    Finished basement with concrete walls 650 SQ FT

    3 4x3 N Facing double pane windows
    2 5x3 S Facing single pane windows

    The attic is blow in insulation of all the types (- asbestos.) Looking to add more venting to it to cool it down in the summer time.

    The only part of the house that isn't ventilated is the garage. There is nothing that splits the upstairs and downstairs as far as load control in the summer unless I close the vents in the basement.

    Here are pictures of the current units. He said he would do a better job on the line set for the AC (not sure how, but it doesn't look great dragging on the ground.) Unfortunately someone scratched off the sticker that showed when the furnace was first installed but I believe it was in the mid - early 90s.

    **Can't post photos yet, will add them when I get 7 posts**

    Any advice appreciated. Also if you think it's a dumb idea to replace before it goes out I'm all ears, but I was told my current units are a ticking time bomb when I bought the house four years ago. The AC compressor has been blowing it's start motor capacitor every other year or so.

    Of the two contractors that quoted the job one uses Day & Night and the other is Rheem. Both come highly recommended from friends who have used them.

    TIA
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  13. Likes dan sw fl liked this post.
  14. #13
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,992
    Post Likes
    Quote Originally Posted by Poodle Head Mikey View Post

    I am far away, not familiar with your area, nor your home -
    but off the top of my well experienced head
    I would guesstimate that 100K BTU of heating is close to double what you are likely to require.
    Certainly 25% too much.

    What you need done FIRST is accurate heat loss & gain measurement and
    calculation by someone who knows how.

    Without that you are just guessing and there is no benefit to you in guessing.
    And there is certainly no need to guess
    - the ability to be very accurate is readily available.

    PHM
    -----------------
    Several Natural Gas bills / usage would be More Than adequate.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Contracting Business
HPAC Engineering
EC&M
CONTRACTOR