Lots of questions after manual J.
Results 1 to 9 of 9
  1. #1
    Join Date
    Oct 2005
    Location
    SE Michigan
    Posts
    3
    This is long, please bear with me

    I am getting the furnace, AC, EAC and humidifier replaced in my 2-story, 2400 sq. ft., 16 year old home.

    I've had 3 estimates and I've got a ton of questions:

    1st guy:
    Lennox G61MAV60C-110 (75,000-110,000 BTU)
    Lennox HS29-042 3.5 ton
    Aprilaire 5000
    Aprilaire by-pass humidifier

    2nd guy:
    Lennox G61MAV60C-110 (75,000-110,000 BTU)
    Lennox HS29-042 4 ton
    Aprilaire 5000
    Aprilaire by-pass humidifier
    Chimney liner

    3rd guy: (selected specifically for heat calc)
    Carrier 58MVP080 (not sure of exact BTU's but, it tops out around 80,000)
    Carrier 38TDB036 3 ton
    Aprilaire 2400
    Carrier fan powered humidifier
    Carrier infinity t-stat

    Where to start?

    Obviously the first two guys grossly over estimated my needs according to manualJ. However, guy 3's total prices are in line with the higher BTU stuff. Shouldn't they be lower? I know, he performed the manual J but, I paid him for it and a blower door test.

    Guy 3 told me he would use a fan powered humidifier on a variable speed system because lower fan speeds wouldn't get humiditiy where I need it. I don't like the idea of having another thing to break. And no one else seemed to think it would be a problem. Any thoughts?

    Guy 3 doesn't like ANY EAC as they emit ozone. I figure it's under EPA guylines and probably much lower than most as it uses media and EAC. He wanted to sell me a PHI cell, I don't think I need it. Any thoughts?

    Guy 3 also tried to sell me a Carrier Infinity 18 38TDB0 (17 seer) AC unit, with current rebate, it isn't much more than the 10 seer unit but, I live in Michigan and have 1/3 (or fewer) cooling days than much of the nation. It's really a good deal, but I just don't think I need it. Plus, it seems like another thing to break.

    Guy 3 is pushing Carrier's Infinity T-stat saying it will basically give me control of things I would not be able to control with a normal Tstat. That I'd "miss the true advantage of my Carrier system." I think he doesn't want to mess with dip switches. Is there a major advantage?

    Guy 3 is recommending an Aprilaire #8364 as the blower door test showed my home is tight and very near it's optimum leakage area.

    Finally, I was told a chimney liner was not needed as my water heater is 55,000 btu's and wouldn't cause a draft problem.

    I know all 3 will do a good job. All 3 work for very reputable firms. The fact that 2 two of them did not do a heat load calc disturbs me but, in my Metro Detroit, it is very difficult to find anyone that will do them. They scoff and tell you they know how to size a system.

    As I understand it, a properly sized system will run more and keep a home more comfortable. I'm always comfortable, if not I add or subtract clothes. I want to save cash. Is a system running more often more efficient than one that doesn't?

    All input is appreciated.

  2. #2
    Join Date
    Nov 2004
    Posts
    2,927
    Originally posted by madjoe
    As I understand it, a properly sized system will run more and keep a home more comfortable. I'm always comfortable, if not I add or subtract clothes. I want to save cash. Is a system running more often more efficient than one that doesn't?

    All input is appreciated.
    yes, you got the right idea.for comfort i would add that only on the coldest day it will run continuously.otherwise the system would not be comfortable on those days

  3. #3
    The first two you have listed have the same model of condensing unit but you have one listed as a 4-ton unit.

    The first two-listed need to do a load calc, PERIOD!
    If not, call the next guy.

    I personally like the bypass humidifiers, and regular media filters. Too many electronics don't get the much-needed maintenance they require.

    Venting with natural draft water requires no chimney liner.

  4. #4
    Join Date
    Oct 2005
    Location
    SE Michigan
    Posts
    3
    Lack of maintenance seems to be a major reason most techs dislike EACs.

    The first guy was afraid that there wouldn't be a sufficient heat on cold days to induce a draft. I was told 55,000 btus would induce all the draft needed in a 6" b-vent.

    No one around here does manual J, unless you beg them to. It's getting to the point that independent people are needed to do the manual J so you can use it for your estimates.


  5. #5
    Originally posted by madjoe
    The first guy was afraid that there wouldn't be a sufficient heat on cold days to induce a draft. I was told 55,000 btus would induce all the draft needed in a 6" b-vent.
    Strike two.

  6. #6
    Join Date
    Oct 2005
    Location
    SE Michigan
    Posts
    3
    I went with the guy that did the manual J.

    Decided to tell him what I wanted after all, it's mostly just opinion anyway.


    I decided to go with an Aprilaire 400 as water is pretty expensive to just throw down the drain. And I didn't see where there would be any difference in performance. Other than replacing the media twice a season instead of once, I couldn't find a downside. Is there one?

    I also went with the Aprilaire 5000 as it seemed to offer the best of everything.

    Carrier 58MVP080 (Infinity 2 stage VS)
    Infinity T stat
    Aprilaire 8126 fresh air controller

    And here's the best part, Carrier 38TDB036. I went in to their showroom to sign paperwork and saw the A/C sitting in there. (The thing is HUGE.) Anyway, the owner proceeded to tell me that the unit was staken out of his house for some reason or anouther after a month or two of operation. He said it would come with a full warranty and, be the same price as the 12 SEER unit I was originally quoted. He said he wanted it out of the way as it would only get damaged sitting there.

    Works for me. Plus, I had a blower door test done and they'll be sealing ducts and adding insulation. They make their money. I save mine.

    Thanks to those of you who posted responses. The guy that did the Manual J was the guy to use. I just wish it was a common practice. Seems like the feds would push for it to be standard.

  7. #7
    Join Date
    Feb 2005
    Location
    Dothan, Al
    Posts
    3,453

    Madjoe

    I sure hope yull be happy with yur new system. Post on here in a year and let us know how it is doing ( and if yo still think it was worth the money spent )

    Richard

  8. #8
    Join Date
    Jan 2004
    Location
    Burleson, Texas
    Posts
    1,741
    [QUOTE]Originally posted by madjoe
    [B] Anyway, the owner proceeded to tell me that the unit was staken out of his house for some reason or anouther after a month or two of operation. He said it would come with a full warranty and, be the same price as the 12 SEER unit I was originally quoted. He said he wanted it out of the way as it would only get damaged sitting there.

    ???????????? used equipment ???????????

  9. #9
    Join Date
    Nov 2002
    Location
    VA
    Posts
    296
    I had a blower door test done and they'll be sealing ducts and adding insulation

    Smart move… The Achilles of the Manual J procedure are infiltration values… I’ve run the numbers through several computer versions, which easily allow changes to the aforementioned, and it is sobering to see the load changes induced by this variable.

    However be aware that running a blower door test on a windy day is extremely questionable… Numerous well-documented studies have convinced many that it requires a high skill level to get meaningful results from a blower door test (even on a calm day).

    On the Aprilaire 5000, I did a fall check on a client’s unit which had particulate counters installed up & down stream of the 5000. The gentleman worked for the EPA and his wife (before she pasted away) was suffering from a chronic respiratory trauma. His studies clearly show that the 5000 is extremely effective for the several weeks after cleaning then performance fell off exponentially. BTW: I still have a copy of his study and I’m waiting for him to alert me on its publication in a professional journal. Bottom Line: clean the media every three weeks, which the gentleman indicated isn’t all that difficult, especially after it becomes second nature.

    Now about the “used” equipment, no comment…

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