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  1. #53
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    Apr 2002
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    11,808
    Quote Originally Posted by adt2 View Post
    Duct leakage on the order of 10% on each system, but it's leaking into conditioned attic space, so I figure that's a wash.
    10% leakage is 400 CFM. Are you drawing retrun air from the attic? Is there a way for air to transfer back from the attic?

    Should feel a constant breeze out of the open attic hatch down into the home

  2. #54
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    Apr 2002
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    Quote Originally Posted by mark beiser View Post
    What the hell, 10 tons of AC in a super tight 4200 sq ft home in Houston?
    That AC contractor needs to be driven out of business!

    That would even be 2-3 tons over sized for the typical leaky stick built house of that size in my area, and our design conditions are for a higher outdoor temperature than Houston...
    Mark

    I seem to recall you fixed a place sized for a ton every 400 sqaure feet. You added a couple thermastors, did the blower door test drastically reduced how much air was leaking in. As far as I can tell you had everything under control.

    Here you have a supposedly tight house, a pair of dehumdifiers the same ton per 400 sqaure feet and yet a problem with humidity.

    I suspect the difference in the two scenarios is your customers were not pumping in humid air ten minutes every hour when the system was off.

  3. #55
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by Carnak View Post
    Mark

    I seem to recall you fixed a place sized for a ton every 400 sqaure feet. You added a couple thermastors, did the blower door test drastically reduced how much air was leaking in. As far as I can tell you had everything under control.

    Here you have a supposedly tight house, a pair of dehumdifiers the same ton per 400 sqaure feet and yet a problem with humidity.

    I suspect the difference in the two scenarios is your customers were not pumping in humid air ten minutes every hour when the system was off.
    Heh, I was just at that house this morning, still having some minor issues, but it has more to do with him wanting to drop the temp in the MBR to 60º at night, from 75º. The recovery mode of the IAQ thermostat doesn't seem to know how to handle that, lol.

    We have the humidity situation in the home well controlled, except for when he runs his multiple nozzle + steam shower without the exhaust fan.

    I have no idea what kind of electric bills the guy has, its never come up in conversation. That particular customer doesn't care a whit how much it costs, he just wants to be able to make it any temperature he wants, and still have good humidity control.
    If more government is the answer, then it's a really stupid question.

  4. #56
    Join Date
    Jul 2008
    Posts
    46
    Okay, I give up. Every time I think I've found a reputable contractor, I get hosed (intentional or not, I don't know). Even within the confines of this thread, I've been told everything from tear it all out and replace it, to leave it all alone and adjust my thermostat. I know everyone is just trying to help, and maybe I'm suffering from a little too much investigation; maybe I'm making a mountain out of a molehill.

    But unlike the guy you mention a post or two back, I DO care a whit about what it costs to run the system. I think I've made it clear that I'm not expecting to cool 4200sf to 70 degrees all day for $100 a month. On the contrary - we leave the thermostats set much higher than we find comfortable because I am not willing to pay through the nose for cooling costs. I thought by investing all the extra money - and believe me, it was not an insignificant amount - up front to insulate and weatherize, I could avoid precisely this situation. Never having built a home with the fancy insulation and the high-falutin' windows and what-not, I didn't know better than to let my good ole boy A/C contractor just go with his gut when he installed all this crap.

    So now, all I want is for somebody who knows what they're doing to come over here, look all this stuff over, and give me an opinion I can believe in. My wife asks me every time I go through this, "Well, did he know what he was talking about?" and my answer is always the same: "He seemed believable, but unfortunately, I don't know enough about this stuff to know whether he's making sense or not."

    So, if anybody has any suggestions for a reputable guy in the Magnolia area, I'm all ears.

  5. #57
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    Apr 2002
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    well with the tight house, the two dehumidifiers, you should be able to just about keep what ever temperature you wanted with in reason, with good humidity control but that is not happening.

    So something else is really wrong besides just an oversized system.

    SO I will give you a test to try, but I need you to clarify exactly what happens in your home.

    The first thing I need you to verify is this 10 minutes of fresh air when the system has been off in an hour.

    Does this start your air handler fans to draw in some fresh air though a fresh air duct connected to the return air ducts?


    If it is thorugh the air handler, does this happen with both air handlers?

  6. #58
    Join Date
    Jul 2008
    Posts
    46
    Okay, I just climbed up in the attic and checked this out. There are two "April Aire" labeled controls on a piece of rigid (probably 6" or 8") duct that runs from where the return air enters the air handler up and out the roof. One of the boxes is facing away from me; not sure what it does, but I assume it controls a damper. The other box has a dial on it that says something like "Minutes per cycle" or "Minutes per hour." It was set on about 10 (between 5 and 15, but closer to 15). The only other options are "Off" and "Test."

    I turned it off. I did not climb into the other attic, but I assume they are the same. I believe that when the fresh air intake is "activated," it signals the air handler to kick on. As I mentioned before, the unit runs about 10 minutes per hour, even when there is no load on the system.

  7. #59
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    Apr 2002
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    if it is what I expect, you will have the same problem if you put smaller equipment in. If you go ultra high seer you will save only a few dollars tops on your power bills unless you solve the root problem.

    You need to approach it like this. Find out where the humidity is coming from and reduce what gets in. Then make the system you have remove as much mositure as it can. You already have all the gear in place to have a cool dry home, it just is not working correctly.

  8. #60
    Join Date
    Apr 2002
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    well I wish I was there to see this, but what you need to do is to stop that fresh air from getting pumped in when you have the system set up for 82.

    A house insulated like yours, with the drapes drawn, should take a long time to heat up from 74 to 82,for atypical work day it would probably be off easily for 6 hours before and most likely would only come on when you had the thermostat programmed to recover.

    So when you set it to 82 I am assuming you and wife are working , kids at school, no one is home.

    Let me see if I can find some info on what april aire uses to cycle the fan. I got a feeling you should be setting the 5 to 15 minute dial to off. I just want to see if this is a fancycler or something to do with the dehu.

  9. #61
    Join Date
    Jul 2008
    Posts
    46
    Now that you mention it, the guys that were here doing the energy audit did say something about the house "holding temperature" very well. Apparently it also holds humidity.

    As I said, I have turned the air intake on that side of the house off. If you think it's a good idea, I'll turn the one on the other side off, too (as I said in another post - what can it hurt at this point?).

    I appreciate your help. It still seems to me that I've got too much air in the house; it just cools the place down too quickly. But I'm willing to investigate my alternatives before I pull the trigger.

    Thanks again for your help.

  10. #62
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    Apr 2002
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    11,808
    is this the control?


  11. #63
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    Apr 2002
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    if that is it, then try switching the other one off as well.

    These can be installed several ways as far as I can tell. One way disables it once it is so warm outside and the indoor RH is higher than 55%

    When they do not use an optional temperature sensor it is possible that they operate strictly on the timer mode. So when you have the system off because it is 'set up to 82' it is probably pumping in air for 10 to 15 minutes on the hour. Maybe after three or four cycles like this it probably has your house warmed up enough to get the AC to come on and if you think it short cycles trying to maintain 74, just imagine it trying to maintian 82

    This hour thing is just a factoiry default, it could be 2, 3 or 4 hours but from your description it sounds like it is every hour.

    They could have installed it with the temperature sensor so it may not be the humidity pump, but a couple days with it switched off you should notice a difference if this is the problem.

    If there is some manual damper in that same ducting with the aprilaire morotrized damper try closing it half off also.

  12. #64
    Join Date
    Jul 2008
    Posts
    46
    Yep, that's the control. I'll get up in the other attic and shut the second one off this evening. Maybe I'll be able to see what the other box is.

  13. #65
    Join Date
    May 2002
    Location
    Houston Texas
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    6,321
    ADT I just read through this thread. You have more than double the A/C capacity you need for your home. I just did a SIP home in your area; 2400 sq.ft. 17,700 BTU's total load 11,700 Latent and 6,000 sensible. We installed a Bryant Evolution two stage 2-ton with three stage heat strips (heat load was only 2,200 BTU’s) and a UHC90 Therma Stor dehumidifier.

    First off you should of had a single two stage system installed most likely a 4-ton but would need to verify with load calc. I am not a fan of the AprilAire unit Therma-Stor is much better and more efficient and one UHC150 would have done the whole house and they have a very nice programmable control.

    Depending on your current ductwork it may be possible to install a zoned system which would allow for a smaller system.

    What are the initials of the installing company?

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