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  1. #14
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    Quote Originally Posted by 54regcab View Post
    Unvented attics with spray foam applied to the bottom of the roof decking are the ideal setup. Air handler and ductwork is in conditioned space, access for maintenance isn't impeded by itchy insulation. Unfortunately insulation contractors are talking 5 figures to spray foam a typical 2,000 sq ft house in our area.
    Murray Woodgate, previously known as Carnak, would agree with you. Although I am not completely on board with Murray's conclusions about sealed, unvented attic spaces in all situations, I do concede that Murray is someone who'se ideas need to be considered.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  2. #15
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    Quote Originally Posted by RoBoTeq View Post
    To not keep the heat down in attics with forced air ventilation because there may be issues with leakage from inside of the dwelling is the dumbest argument I have heard in our industry.
    Yeah, that Joe Lstiburek guy, the Florida Solar Energy Center, and all the other building science and utility organizations that have actually done testing sure are dumb...
    Last edited by mark beiser; 07-16-2012 at 02:02 AM.
    If more government is the answer, then it's a really stupid question.

  3. #16
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    Quote Originally Posted by RoBoTeq View Post
    To not keep the heat down in attics with forced air ventilation because there may be issues with leakage from inside of the dwelling is the dumbest argument I have heard in our industry.
    I agree with the part of your quote I placed in bold type.

    I don't flat out disagree with forced ventilation. I do think, however, the caveats raised by Mark and others should be stated, not glossed over. The end user can then investigate further for him or herself if depressurizing their attic will incur said cautions, or in the case of combustion air appliances, possible dangers.

    My overall pet peeve is how we build houses in this country, especially in southern and western regions, to be summertime heat collectors. In researching metal roof options for our own house, I've learned what the true solar reflectivity of the common composition shingle is: 0.09. Galvalume metal roofing or similar product: 0.60 or better. Even the painted metal products are signficantly better than asphalt.

    It is true that comp shingling is for the most part less expensive than more durable, more reflective roof coatings. But is that subsidized by monthly summer utility bills, perhaps?

    Reducing heat gain to any attic is a great idea. My thought is to nip it in the bud. Attic ventilation primarily arose in cold climates to prevent condensation in the attic in winter, which in itself is caused by a leaky house. Natural attic ventilation for southern and western regions simply can't keep up with the heat gain. So to me that reduces smart options to:

    A) seal the envelope and mechanically ventilate the attic

    B) use a highly reflective roofing material and possibly insulation directly beneath it

    C) Never put ducts or any combustion appliance in the attic from the start, then insulate the attic floor to a high level, coinciding with an airtight ceiling, and then ventilate the attic naturally

    D) Foam the roof deck and make the attic conditioned space. This must be done carefully to avoid moisture problems that have been reported with certain foam applications and climates

    For most of us poor slobs stuck under traditional attics, "A" is the most appealing due to lower cost. "B" is desirable when reroofing needs arise and one's budget allows. "C" is a new construction detail that to me should be enforced national building code. "D" being a reasonable alternate.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  4. #17
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    Just because attic ventilating can be done wrong does not mean we should not provide attic ventilation properly.

    In one of my homes cooled with a slightly undersized attic system, the only time that cooling system did not keep up with outdoor temps was the day when my attic fan stopped working.

    When I installed that system, I sealed around openings such as bathroom fans and ceiling electrical fixtures and insulated the ceiling a little better than it was originally done. The duct system was well sealed and insulated with a good vapor barrier, including duct sealant on all vapor barrier seams. The only difference between that system being able to do it's job on really hot and sunny days or not was the attic fan.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  5. #18
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    Quote Originally Posted by RoBoTeq View Post
    Just because attic ventilating can be done wrong does not mean we should not provide attic ventilation properly.
    I believe I was saying the same thing in my previous reply. My point "A" covers this aspect.

    I would agree with you that it's absurd to say one should NEVER mechanically ventilate an attic, EVER. On the opposite hand it's just as absurd to recommend mechanical attic ventilation across the board, without any regard to the condition of the attic and house air boundary.

    In one of my homes cooled with a slightly undersized attic system, the only time that cooling system did not keep up with outdoor temps was the day when my attic fan stopped working.

    When I installed that system, I sealed around openings such as bathroom fans and ceiling electrical fixtures and insulated the ceiling a little better than it was originally done. The duct system was well sealed and insulated with a good vapor barrier, including duct sealant on all vapor barrier seams. The only difference between that system being able to do it's job on really hot and sunny days or not was the attic fan.
    You made my point well with your quote above. You took precautions and noted success with the ventilator. How often is that done? If folks don't know the possible downfalls, they may forge ahead thinking everything's gonna be just peachy, only to potentially wonder why it's not so great in the end. If they are made aware of potential drawbacks, they can decide the extent they wish to evaluate and counteract said drawbacks, or at least be better informed if one they hire to install mechanical ventilation does not mention these potential problems.

    It also reinforces the point that if we did a better job of reducing the amount of heat reaching into the attic in the first place, all this discussion about ventilation by whatever means would be reduced.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #19
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    Quote Originally Posted by Shophound View Post
    I believe I was saying the same thing in my previous reply. My point "A" covers this aspect.

    I would agree with you that it's absurd to say one should NEVER mechanically ventilate an attic, EVER. On the opposite hand it's just as absurd to recommend mechanical attic ventilation across the board, without any regard to the condition of the attic and house air boundary.



    You made my point well with your quote above. You took precautions and noted success with the ventilator. How often is that done? If folks don't know the possible downfalls, they may forge ahead thinking everything's gonna be just peachy, only to potentially wonder why it's not so great in the end. If they are made aware of potential drawbacks, they can decide the extent they wish to evaluate and counteract said drawbacks, or at least be better informed if one they hire to install mechanical ventilation does not mention these potential problems.

    It also reinforces the point that if we did a better job of reducing the amount of heat reaching into the attic in the first place, all this discussion about ventilation by whatever means would be reduced.
    I understand that you and I are on the same page. I was reiterating how ridiculous it is to make a blanket statement that attic fans should never be used because other conditions of the house may not be suitable. We should always fix the problems before installing any system.

    An HVAC contractor that understands all of the variables can turn a few hundred dollar attic fan install into a few thousand dollar job that will greatly benefit the consumer. That is a win-win situation. Just telling everyone that attic fans are bad benefits no one.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  7. #20
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    Quote Originally Posted by RoBoTeq View Post
    I understand that you and I are on the same page. I was reiterating how ridiculous it is to make a blanket statement that attic fans should never be used because other conditions of the house may not be suitable. We should always fix the problems before installing any system.

    An HVAC contractor that understands all of the variables can turn a few hundred dollar attic fan install into a few thousand dollar job that will greatly benefit the consumer. That is a win-win situation. Just telling everyone that attic fans are bad benefits no one.
    The percentage of HVAC contractors who would know how, and perform, air sealing in conjunction with an attic fan install is likely to start out with a .00%
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  8. #21
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    Quote Originally Posted by tipsrfine View Post
    The percentage of HVAC contractors who would know how, and perform, air sealing in conjunction with an attic fan install is likely to start out with a .00%
    I disagree. But even if this were accurate, does it make more sense to educate contractors or just not do the right thing because we're all too stupid?
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  9. #22
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    Quote Originally Posted by RoBoTeq View Post
    I disagree. But even if this were accurate, does it make more sense to educate contractors or just not do the right thing because we're all too stupid?
    It makes a lot of sense to educate contractors, but we have to educate the consumers also. I don't know what the answer is, but I do know you are smart & experienced enough to know that what I said (in your quotes) is true, and your statement of "I disagree" is less than honest, to put it mildly.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  10. #23
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    Quote Originally Posted by tipsrfine View Post
    It makes a lot of sense to educate contractors, but we have to educate the consumers also. I don't know what the answer is, but I do know you are smart & experienced enough to know that what I said (in your quotes) is true, and your statement of "I disagree" is less than honest, to put it mildly.
    Why in the world would you deliberately insult me by calling me dishonest because I disagreed with you? Am I reading this wrong, or are you being an ass?
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  11. #24
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    Quote Originally Posted by RoBoTeq View Post
    Why in the world would you deliberately insult me by calling me dishonest because I disagreed with you? Am I reading this wrong, or are you being an ass?
    Not trying to be an ass, but when you put a statement out that absurd, you have to expect to be called out on it. The percentage of HVAC contractors who are going to install an attic fac and include air sealing the attic from the conditioned area of a home starts at .00%. Your statement to the contrary and expecting anyone to believe it is what is insulting. I think you've been spending too much time in the ARP forum.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  12. #25
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    Quote Originally Posted by tipsrfine View Post
    Not trying to be an ass, but when you put a statement out that absurd, you have to expect to be called out on it. The percentage of HVAC contractors who are going to install an attic fac and include air sealing the attic from the conditioned area of a home starts at .00%. Your statement to the contrary and expecting anyone to believe it is what is insulting. I think you've been spending too much time in the ARP forum.
    Maybe I am just not understanding your cryptic way of trying to put across a point. What exactly are you implying about the number of contractors who are not aware of how to properly seal ceilings to attic spaces that are to be ventillated? If you are claiming that 0% of contractors understand this, that is what I stated that I disagree with. That is what you called me dishonest for disagreeing with you on. If you have something specific to state, then state it clearly.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  13. #26
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    Quote Originally Posted by tipsrfine View Post
    The percentage of HVAC contractors who would know how, and perform, air sealing in conjunction with an attic fan install is likely to start out with a .00%
    Nothing cryptic about what I said. Knowing and Doing are not the same thing.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

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