Results 1 to 12 of 12
  1. #1

    Question Urgent A/C and furnace replacement questions

    Hi, Im going to replace the original builder A/C and the furnace that are over 20 years old because of refrigerant leakage. My situation is as follows:
    Baltimore area
    Built in 1992
    2-story, 2,600 sq ft, plus 800-1000 sqft finished basement
    Summer thermo set at 77 degrees, winter thermo set at 67 degrees
    Natural gas furnace and indoor coil installed in basement
    Current (builder) system: outside unit HEIL CA5042VKA1 (3.5 ton?), inside unit NUGE100BG01 by Inter-City Products.

    Im quoted a few Trane systems (mostly 4-ton). The one Im leaning towards is:
    TRANE 4TTR6042B XR16, 3.5 Ton; XV80 TUD2C080B9V4, 80%, Two stage, Variable speed. Matching coil to achieve SEER 16.0, EER 13.0. Honeywell 8000 series thermostat.

    Is this a reasonable system? And specifically:

    1. The contractor had not done a Manual J calculation when I asked him. He said the ductwork is good to handle even a 4-ton system. I asked him whether 4-ton would be too big, and he answered 3.5 ton would be okay but too few models to choose from in the 3.5 ton category.
    2. In terms of extracting moisture for better comfort, is the single-stage XR-16 good when pairing up with the variable-speed blower? Or should I pay more for a 2-stage XR17?
    3. Is it okay to replace the current 100K input BTUH furnace with the 80K BTUH XV80? With the 2-stage, variable-speed XV80, will the house get enough heat in winter?
    4. Is the Honeywell 8000 series thermostat good enough? But Ive seen a lot of posts advocating for VisionPro IAQ; What's the cost vs. benefit of an upgrade?

    As the temperature is rising in the next couple days, I really need to make a decision as soon as possible. Greatly appreciate any feedback from the pros here!

  2. #2
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,239
    Unless there is a legitimate reason, I would not want an 80% eff furnace. Upgrade to the XV95 and add a good two stg thermostat like the HW VP IAQ.

    IMO

  3. #3
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    "Matching coil to achieve SEER 16.0, EER 13.0."

    I would ask them to specify the manufacturer and model number for this coil. As it is listed, it may not be a Trane coil.

    The 80k is probably the correct choice of the XV80 models with blowers capable of supporting a 3.5 ton air conditioner. 2-stage furnaces provide the most comfort when sized correctly, and 100k is likely too large even if the existing had a 100k input capacity, especially if current ductwork is less than sufficient as the variable speed furnace will work harder to move a larger volume of air. But without a load calculation, it's a guess. A load calculation should be done to verify, but for this area in the average 2600 sqft home, 80k/3.5 ton doesn't sound too far off. Is there an issue with PVC venting of the 95% furnace?

    The VP 8000 (TH8321) is a good choice and can overcool to dehumidify. The thermostat should be set up to properly stage the furnace, not the furnace control board timer. But the VisionPRO IAQ is definitely the better choice. It can be configured to slow the blower down on a call to dehumidify, which removes more moisture from the air.

  4. #4
    Thank you tigerdunes and RyanHughes for your timely replies. I did ask the contractor about 95% furnace models, but he said 95% would need PVC flue piping, as Ryan guessed. Is that a big job? I can ask the contractor for a quote.

    I'll also find out from the contractor the price difference between the VisionPRO IAQ and the Honeywell 8000. And ask for a Trane coil. And load calculation.

  5. #5
    Join Date
    May 2013
    Location
    Kalamazoo, MI
    Posts
    4
    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.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.
    Last edited by jpsmith1cm; 07-15-2013 at 06:44 AM. Reason: non AOP Pro Member

  6. #6
    Thanks for sharing your perspective, David. Due to the low temp setting I usually have in winters, my fuel savings may be on the moderate side. I calculated the annual $ savings based on last heating season's gas usage. And once the quote is in I can determine the cost recovery period.

    Through my research on these forums I do find out that a matching configuration is very important.

  7. #7
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,921
    David F

    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.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.

  8. #8
    Join Date
    Sep 2003
    Posts
    1,677
    Some other factors to consider regarding 80% vs 90%

    How long will you be in the home ? If you are going to be there for the long term a 90 % may make more sense.

    If they install the 90% furnace make sure that they use 2 pipes one for inlet combustion air the other to vent the flue to the outside, some contractors shortcut this method.

    If they put the 90% furnace in and you have a water heater also vented into the same chimney make sure they properly test and or line the chimney for just the water heater flue. Also an added cost but one that needs to be done.

  9. #9
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,637
    Quote Originally Posted by seanjon View Post
    Hi, Im going to replace the original builder A/C and the furnace that are over 20 years old because of refrigerant leakage. My situation is as follows:
    Baltimore area
    Built in 1992
    2-story, 2,600 sq ft, plus 800-1000 sqft finished basement

    2. In terms of extracting moisture for better comfort, is the single-stage XR-16 good when pairing up with the variable-speed blower? Or should I pay more for a 2-stage XR17?


    As the temperature is rising in the next couple days, I really need to make a decision as soon as possible. Greatly appreciate any feedback from the pros here!
    Regarding perfect %RH throughout your home in a Green Grass Climate A whole house dehumidifier combined with a simple medium SEER a/c will maintain <50%RH throughout your home including your basement. Two stage/VS speed a/c is unable to remove moisture with a significant cooling. During low/no load cooling loads, +60^F outdoor dew points, and moisture from the occupants, the whole house dehumidifier will remove the 1-4 lbs. of moisture per hour to maintain <50%RH.
    The VS fans are nice for rebalancing the temps in your home including the basement.
    Check out the Ultra-Aire 70H, a sponsor of this site.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  10. #10
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,031
    Quote Originally Posted by seanjon View Post
    1. The contractor had not done a Manual J calculation when I asked him. He said the ductwork is good to handle even a 4-ton system. I asked him whether 4-ton would be too big, and he answered 3.5 ton would be okay but too few models to choose from in the 3.5 ton category...
    The Baltimore area is humid; 2.5% summer design is 89F DB & 76F Wet Bulb for around 55% RH; you never want to oversize the A/C in that climate.

    Winter design at 99% is plus 10F AP to plus 14F Co; much warmer than -13F below zero here in Lacrosse, WI.

    I would question whether there is enough Return Air filter area for either 3.5 or 4-Ton; 325-sq.ins per ton of cooling for best efficiency of air flow, never using 1" pleated filters.

    The lower the resistance on the Return-side the more airflow on the Supply-side.

  11. #11
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,031
    Quote Originally Posted by seanjon View Post
    1. The contractor had not done a Manual J calculation when I asked him. He said the ductwork is good to handle even a 4-ton system. I asked him whether 4-ton would be too big, and he answered 3.5 ton would be okay but too few models to choose from in the 3.5 ton category...
    The Baltimore area is humid; 2.5% summer design is 89F DB & 76F Wet Bulb for around 55% RH; you never want to oversize the A/C in that climate.

    Winter design at 99% is plus 10F AP to plus 14F Co; much warmer than -13F below zero here in Lacrosse, WI.

    I would question whether there is enough Return Air filter area for either 3.5 or 4-Ton; 325-sq.ins per ton of cooling for best efficiency of air flow, never using 1" pleated filters.

    The lower the resistance on the Return-side the more airflow on the Supply-side.

    A Manual D should be performed on that duct system, so you know what the score is!

  12. #12
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,763
    Quote Originally Posted by seanjon View Post
    Thank you tigerdunes and RyanHughes for your timely replies. I did ask the contractor about 95% furnace models, but he said 95% would need PVC flue piping, as Ryan guessed. Is that a big job? I can ask the contractor for a quote.

    I'll also find out from the contractor the price difference between the VisionPRO IAQ and the Honeywell 8000. And ask for a Trane coil. And load calculation.
    4 ton probably won't be able to keep your RH as low as your 3.5 ton does.
    Contractor locator map

    How-to-apply-for-Professional

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

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event