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  1. #27
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by George2 View Post
    You had a 2 ton that worked fine and the contractor installed a 2.5 ton.............that was brilliant on his part.

    It cost you more to purchase, operate and (insult to injury) it doesn't do the job the way it should.
    What's worse, with the insulation and air sealing he said he did, there's a chance he only needed a 1.5 ton. Especially if a 10+ year old worn out 2 ton was keeping up in the hottest weather.

  2. #28
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,606
    Quote Originally Posted by motoguy128 View Post
    What's worse, with the insulation and air sealing he said he did, there's a chance he only needed a 1.5 ton. Especially if a 10+ year old worn out 2 ton was keeping up in the hottest weather.
    That's a BIG 10-4. I wasn't sure when he improved the "envolope", but if he did the work after the install...............he certainly made it far worse.

    I have always said..........if you are to err on size, go smaller.

  3. #29
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by George2 View Post
    I have always said..........if you are to err on size, go smaller.
    Absolutely. There's already fudge factors built into Manual J, and you're only talking about 10-15 days in a cooling season that you might have to close a few more blinds, precool the space 1-2F in the morning, or just live with it falling behind just a little but keeping humidity nice and low.

    OT- I had to check a map to make sure i was still in Iowa. It's 99F and 22%RH outside according to weather.com ... more like Pheonix weather than Midwest. Actually with the seasonal rains out west everwhere but the central us, we are the hottest place in the country right now. I might move the cactus I have outside so it feels right at home. Then again, 2 months from now leaves will be falling and we'll have frost on the ground.

  4. #30
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,606
    Quote Originally Posted by motoguy128 View Post
    Absolutely. There's already fudge factors built into Manual J, and you're only talking about 10-15 days in a cooling season that you might have to close a few more blinds, precool the space 1-2F in the morning, or just live with it falling behind just a little but keeping humidity nice and low.

    OT- I had to check a map to make sure i was still in Iowa. It's 99F and 22%RH outside according to weather.com ... more like Pheonix weather than Midwest. Actually with the seasonal rains out west everwhere but the central us, we are the hottest place in the country right now. I might move the cactus I have outside so it feels right at home. Then again, 2 months from now leaves will be falling and we'll have frost on the ground.
    Yes, it's in the mid 90's here and you would never know it. I didn't think we (living on the Mississippi) could ever see RH that low. Wow.

  5. #31
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    The river doesn't have that much influence on humidity and weather patterns. Its' large, but even where I live near Lock and Pool 19, the widest parts, it's still only 0.5-1 miles wide and more improtantly, the water temperatures are pretty close to average ambient temps most of the time. That's like expecting a small inland lake to dramatically raise your humidity. I think it has some small influence overnight, but nothing like living along the Great Lakes or the Ocean. Mostly it just means you get a lot more river bugs flying around all summer.

    What I notice most, is stratification and convection currents due to local elevaton changes. Meaning that it's 3-5F warmer at my house 150ft up on the bluff, than it is 1 mile down the road, down a hill near the water. Cool air falls into valleys and low spots. I remember riding bicycles in hilly central PA and in summer mornings, it could easily be 10F cooler as you dropped into a valley.

    Again, the RH is low because in a normal summer thre's ground maisture constantly evaporating throughout hte region. With a shift in weather patterns keeping rain out of the region, there's no ground mosture and even plants have slowed their respiration rates and are even dropping leaves early. Dewpoints are usually having higher in Fall than Spring because ground temps are high so overnight temps stay high despite less sunlight. Normally we'd have dewpoints aound 60-70F throught August. Its' been hanging in the 50's and now 40's.

  6. #32
    My Trane dealer has said he would replace my 2.5 ton XL15I heat pump model 4TWX5030A1000AA with the 2 ton unit model 4TWX5024B1, also a 15 seer unit, if I would sign a paper saying I would not complain later if it does not sufficiently cool my house. I told him I was interested but wanted to think about it. My primary concern is that it matches the rest of my system, an XV80 natural gas furnace model TDD080R9V3F5, and a 3 ton coil model 4TXCB036BC3HCAA. Is my current 3 ton coil a match for this 2 ton heat pump.

    I told him I was concerned my 3 ton coil would be too large and he assurred me the 3 ton larger coil would be more efficient at dehumidification than a smaller coil simply becuase it is larger. This I believe is opposite what I have read here. Is this correct?

    Also, he tried to tell me that my 2.5 15 seer unit had about the same cooling BTU's as was my old 16 yr old 10 seer 2.0 ton system which is why he felt I cold go with a 2.5 ton unit. Is there any basis to this claim?

    He sent me an ARI comparison showing performance specs of the new heat pump with my current coil and the new heat pump with this coil 4TXCB025BC3. The ARI comparison shows a higher rating at 95/75 with my current coil.

    Thanks for all of the help and ideas....

  7. #33
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,614
    Coil size does havesome bearing on humidity removal but its more about the amount of air flowing through the coil. Have they tried setting the airflow at 350 cfm per ton that would be 875 cfm

  8. #34
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,271
    Quote Originally Posted by supermaxhd View Post
    My Trane dealer has said he would replace my 2.5 ton XL15I heat pump model 4TWX5030A1000AA with the 2 ton unit model 4TWX5024B1, also a 15 seer unit, if I would sign a paper saying I would not complain later if it does not sufficiently cool my house. I told him I was interested but wanted to think about it. My primary concern is that it matches the rest of my system, an XV80 natural gas furnace model TDD080R9V3F5, and a 3 ton coil model 4TXCB036BC3HCAA. Is my current 3 ton coil a match for this 2 ton heat pump.

    I told him I was concerned my 3 ton coil would be too large and he assurred me the 3 ton larger coil would be more efficient at dehumidification than a smaller coil simply becuase it is larger. This I believe is opposite what I have read here. Is this correct?

    Also, he tried to tell me that my 2.5 15 seer unit had about the same cooling BTU's as was my old 16 yr old 10 seer 2.0 ton system which is why he felt I cold go with a 2.5 ton unit. Is there any basis to this claim?

    He sent me an ARI comparison showing performance specs of the new heat pump with my current coil and the new heat pump with this coil 4TXCB025BC3. The ARI comparison shows a higher rating at 95/75 with my current coil.

    Thanks for all of the help and ideas....
    Moment of truth. This is all about setting up your current a/c with correct air flow to get a 45-50^F coil temp. An a/c with a slightly smaller coil will not solve your humidity problems. Most of a/c posters on this site claim the that the a/c is oversized when the %RH to too high. When there is low/no cooling loads, a smaller a/c will not maintain <50%RH. You need supplemental dehumidification from a whole house dehumidifier for <50%RH during low/no cooling loads and high outdoor dew points.
    Keep us posted on how this all turns out.
    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"

  9. #35
    I am having my 2.5 ton xl15i replaced with a 2 ton xl15i today. I am getting my tcont800 (without a dehumidify feature) replaced with a tcont803 maybe (the 803 has dehumidify feature but not the kind that will control the variable speed fan, it just runs longer by cooling below the set point, at least that is what I am being told). I am not sure I really want that thermostat. Is it correct that there are thermostats that will control the fan speed of my variable speed furnace to provide better dehumidification?

  10. #36
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Yes. Either you go with the 900 series Trane thermostats, or, there's a the White Rodgers IF95-1291 (I have one on my downstairs system) and the the Honeywell Vision Pro IAQ. THe Honeywell is a little better thermostat but a little more expensive and a little more involved to set-up.

  11. #37
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    OH, you can always just get a basic manual dehumidistat and sue that. But if you going through to effort to downsize the AC unit, you might as well put in the VIsonpro IAQ and be doen wiht it. Its' also nice because hte relays get located at the equipment, so the wall unit doesn't make a "click" sound. My wife hated the click on our upstairs unit before I install a Carrier Infinity System. SHe said it woke her up sometimes.

  12. #38
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,614
    Since you have a xc furnace get the xl 900 or the xl 950 thermostat they have dehumidify on demand .i dont see why contractors sell the xc communicating furnace then put a defeatured thermostat on it. Might as well use a xv furnace they are cheaper also
    We really need change now

  13. #39
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,926
    Looks like an XV80 to me.

    Sent from my HTC VLE_U using Tapatalk 2

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