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  1. #53
    Join Date
    Jun 2008
    Location
    Perry Village, Ohio
    Posts
    164
    Brian, I'm not a HVAC pro either, but with regards to closing the supplies or closing a return, my understanding is this. If you close a supply to a room, it forces the air to exit some other place that has less resistance. The point is though, that air goes someplace into the house. With the return, if you close that off, it eliminates air from entering the system, so less will be pumped out of the supply.

    So by closing a supply, 100% still exits the system, but by closing off a return that 100% may now be reduced to 50%.

  2. #54
    Join Date
    Aug 2008
    Posts
    56
    Quote Originally Posted by Brian GC View Post
    I am not an HVAC pro but I am very interested in air flow as it related to a heating and cooling system. This is one such thread I find particularly intriguing. These are my observations of the recommendation so far.

    The OP says he has a five year old house with thick blown-in insulation. He undoubtedly has proper wall insulation, dual pane windows, vapor barriers, and a properly sized AC unit. Yet nearly all the advice centers around lowering the temp of the attic, sealing the attic from the living space, or redirecting the supplies through zoning or dampening. But by all means do not tamper with a return because that is a “band aid”.

    Someone recommended dampening the supplies to the downstairs and there were no objections, but doesn’t that restrict airflow as much as dampening a return? Why would restricting supplies be ok for the unit but closing off a return would hurt the unit? The net affect to the unit is the same…it’s being choked.

    A supply adds desirable air to the living space and a return CAN remove undesirable air if placed properly. In this case it would be upstairs. Why is tampering with supplies recommended but focusing on returns a “band-aid”? They both deal with the addition and extraction of wanted and unwanted air.

    Reducing the temp of the attic assumes the hot upstairs condition is caused by the hot attic air, a porous ceiling, but not from rising hot air? Why would the removal of unwanted air not be the other side of the coin from adding wanted air?

    And, I have a question for the OP. What have you learned from all the responses so far? IOW, since you are not going to throw $x,xxx at your problem are you most likely going to seal your attic, insulate your attic, zone (restrict) your supplies, or restrict a return?

    Brian
    It may be helpful to search the hvac-talk threads to understand how zoning systems work.

    The problem the original poster described (two floors and one HVAC system uncomfortable upstairs) is not unusual and often is a balancing issue.
    A zoning system merely helps to automatically balance the system. When zoning is installed properly issues related to restricting supply is minimized.

    This is accomplished with barometric bypass dampers and discharge air temperature sensors.

    It's also important to understand that many duct systems are designed with the intent of slightly restricting supply to either upstairs or downstairs depending on the season using manual dampers.

    Rebalancing for the hot upstairs summer is usually accomplished by your HVAC Pro as part of your spring AC check up. Rebalancing for the cold downstairs winter is usually accomplished by your HVAC Pro as part of your fall Furnace check up. Or you have a zonging system installed and dont worry about it.

  3. #55
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,824
    Quote Originally Posted by energy_rater_La View Post
    I'm going to be in code class for the rest of the week.
    Good move.

    Quote Originally Posted by energy_rater_La View Post
    and energystar...don't just come in and say staple up bubble wrap.
    come on! first off bubble wrap is for wrapping breakables.
    radiant barrier is what you are referring to?
    then explain how the rb is to be installed, or give a informational only site, not a mfg selling products site. you might also want to explain that rb has to cover entire roofline. just a bit harder than what we were trying to achieve here.
    the rb I use is a single sided foil. costs me about .10 per sq ft.
    (compare that to foil bubble foil rb and explain why you would pay or recommend some one else pay 4x the cost for the same performance please)
    and I only install it on the roofline with foil facing into attic space. specific products have specific applications.

    again..best of luck to you OP.
    If one side is foil, and your installing it on the roof line as you say............with the foil facing in, you are installing it backwards! Foil side towards the sky!

    BTW, I pay what you pay for the materials.
    Always here

  4. #56
    Join Date
    Jun 2008
    Posts
    63
    First, go to your local library, and get a book on Weatherization.
    It will tell you what Energy Rater La did in more detail and with color pictures. With minimal costs, you may get major results. Newer homes are much better with weatherization than my 30 yr old home was, but I haven't inspected one yet that couldn't be improved.
    Then add insulation to the uninsulated places you probably have.
    Then see if your HVAC needs changing.

  5. #57
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    Quote Originally Posted by perrybucsdad View Post
    So by closing a supply, 100% still exits the system, but by closing off a return that 100% may now be reduced to 50%.
    Sorry, this is not so. Closing off one or more supply registers increases static pressure at the air handler. Increased static pressure reduces air volume. The total VOLUME of air moved across the cooling coil decreases. For a cooling coil, volume is everything. There will be increased VELOCITY at the remaining registers that are still open, but the original volume the air moved at across the cooling coil prior to the supply vents being closed is now less.

    Return side is not much different. If there is more than one return path, and the second one is blocked off, the first one might see a higher feet per minute VELOCITY across the return air grill, but the VOLUME of air entering the remaining open return air grill is lower.

    The main difference is that the supply side has several ways for air to exit, whereas the return side at minimum has one point of entry.

    Blocking off registers and return grill is NOT the solution. If your return duct is flex, chances are it was not installed with the best care (and may or may not be sized properly). If it is metal or panned joist or ductboard, it could be a sizing issue. Overall, it may not be a horrendous undertaking to fix, but hard to call that shot over the internet, especially with no pictures involved.
    • 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. #58
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    Quote Originally Posted by energy star View Post

    If one side is foil, and your installing it on the roof line as you say............with the foil facing in, you are installing it backwards! Foil side towards the sky!
    Are you talking about staple-up barrier or roof deck with the foil glued onto the decking (typically used in new construction)?
    • 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.

  7. #59
    Join Date
    Mar 2009
    Location
    central illinois
    Posts
    532
    Quote Originally Posted by efelkey View Post
    I am not a HVAC professional, but would love some advice on what I can do about my upstairs of my home being too warm. I have a 5 year old home with soffit and ridge vents. I have an AC unit that does a great job on the main floor. I can not get my second story comfortable without "cracking up the AC" which costs a lot of money and makes the main floor too cold. I have spoken to some people about attic fans, whole house fans, second AC units, and "reflective" products.

    If anyone can help me enjoy both stories of my home I would be greatly appreciative.

    Thanks

    Eric
    do not know where you live, here in st.louis it gets pretty hot. people with one unit think they are going to cool two floors ain't going to happen. shutting off dampers, adding sensors don't waste your money get another unit for upstairs!!!!!!!!!!!!!!!!!!!!!!!
    work to live not live to work.

  8. #60
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,316
    yes radiant barrier is the product shophound
    as it is an existing house rb decking isn't an option.
    fwi.. I did talk to code instructor..he says only in living
    space will foam sheathing need to be covered..preferably with sheetrock for fire spread rating.
    I'll be doing a diagnostic on his house later next week..we are thinking of inviting some of the
    serious members of the class along.
    I know your R-max..open cell with not so
    reflective plastic type surface...razor knife tears it up with it
    is time to change the blade..messy stuff. gotta say I perfer
    closed cell. just easier to work with..and I learned to not use blue board (or pink) because of the plastic coating...what a pita when you are making cuts all day.


    sorry if you think I came down hard on you energystar..

    you sign up with that name.. I expect you to know your products
    and installs and be willing to explain.
    energy star..the program.... is
    serious business for me, with several years of hundreds of
    energy star homes and 3 years of awards from them under my belt
    I know that it is a high standard that is not easily achieved.


    first ..radiant barriers do NOT face the roof decking any more than
    they are installed lying on top of insulation on attic floor.
    check florida solar energy center...building science or... just think about it. dust build up lessens reflectivity of foil, when rb is installed with foil facing up. 50% reflectivity in 5 years.
    dust ...attic...gravity...

    and I paid a couple of hundred bucks for a warehouse full of rb
    about 10 years ago. heck of a deal. I estimate it was over 3,500 rolls of 2' and 4'
    so no..I hardly think we pay the same prices any more than I believe that you understand proper install of this product.

    its folks like you who make it harder on the rest of us who spend the time, effort and money to learn thru continuing ed and ....
    real life experience.

    learn your stuff, its a tough world.
    making that kind of mistake (wrong install of rb) and cost the homeowner big dollars is a hefty price to pay for education.

    if this seems harsh, maybe it is. but better you know that there are areas you need to listen (or read) first, before you speak (or write) than for you to make a blunder in front of a client. if they are happy with your work
    they tell 5 people..if they are not happy they tell 10 times that many.

    all that said...glad to see you got your pro status. congrats.

    sorry OP for the interruption of your thread. sincerely.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  9. #61
    Join Date
    May 2009
    Posts
    12
    Quote Originally Posted by Brian GC View Post
    And, I have a question for the OP. What have you learned from all the responses so far? IOW, since you are not going to throw $3,000 at your problem are you most likely going to seal your attic, insulate your attic, zone (restrict) your supplies, or restrict a return?

    Brian
    I haven't done anything yet. I am looking into a heat audit currently(whatever that is). I do not have $3000 to spend on any option. I have looked at insulation and sealing the attic but seems to be pretty good. The issue, as far as I see it is the heat radiating from the attic or being trapped by the insulation. I have another contractor coming to look at my system next week too. I don't know what to do, since I am not in a position to spend 3 grand. I am not looking for a band aid, but don't have an exact plan at the moment.

  10. #62
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    3,494
    a heat audit should be where an energy specialist comes into your house and shows you where your heat is flowing in and out of your house. there are blower type, and infrared video/imaging types, and a mix of both. that is a good place to start. let us know what they find.
    The TRUE highest cost system is the system not installed properly...
    The three big summer hearththrobs...
    Mel Gibson
    Dwane Johnson
    The A/C repairman

  11. #63
    Join Date
    Jun 2008
    Location
    Perry Village, Ohio
    Posts
    164
    efelkey, do you have a quote on what one of those cost in your neck of the woods? I have always thought of getting one done to my house as I have some similar issues as you do, but have no idea what the audit costs.

  12. #64
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,824
    Quote Originally Posted by energy_rater_La View Post
    sorry if you think I came down hard on you energystar..

    you sign up with that name.. I expect you to know your products
    and installs and be willing to explain.
    energy star..the program.... is
    serious business for me, with several years of hundreds of
    energy star homes and 3 years of awards from them under my belt
    I know that it is a high standard that is not easily achieved.
    Awards? Awards for what? Please tell......



    Quote Originally Posted by energy_rater_La View Post
    first ..radiant barriers do NOT face the roof decking any more than
    they are installed lying on top of insulation on attic floor.
    This brings me back to my first post. When I was trying to help the OP. You decided to jump all over me about "bubble wrap" remember? If you are installing a Radiant Barrier in an attic, you install it with the reflective side up facing the the sky. Yes you could lay it on the insulation in the attic, and yes it will get dusty over time. This dust will not cut it's efficiency enough not to install it in the first place. What do you do? Do you face the reflective side IN so it is less or not even effective from day one? Me, I staple the Radiant Barrier up to the bottom of the roof rafters "the roof line like we said" you just brought up laying it on the insulation, not me. I staple it the roof rafters with the reflective side facing out, every time, as it should be installed.[/QUOTE]




    Quote Originally Posted by energy_rater_La View Post
    check florida solar energy center...building science or... just think about it. dust build up lessens reflectivity of foil, when rb is installed with foil facing up. 50% reflectivity in 5 years.
    dust ...attic...gravity....
    Who said anything about laying it flat on the insulation? I have been talking roof line.



    Quote Originally Posted by energy_rater_La View Post
    and I paid a couple of hundred bucks for a warehouse full of rb
    about 10 years ago. heck of a deal. I estimate it was over 3,500 rolls of 2' and 4'
    so no..I hardly think we pay the same prices any more than I believe that you understand proper install of this product.
    10 years ago? A computer cost 3k 10 years ago, what do they cost now? I will pay the same price you pay for this product.

    Quote Originally Posted by energy_rater_La View Post
    its folks like you who make it harder on the rest of us who spend the time, effort and money to learn thru continuing ed and ....
    real life experience.

    Quote Originally Posted by energy_rater_La View Post
    learn your stuff, its a tough world.
    making that kind of mistake (wrong install of rb) and cost the homeowner big dollars is a hefty price to pay for education.
    The homeowner is my main concern. I have always installed to manufacturers specs and code.


    Quote Originally Posted by energy_rater_La View Post
    if this seems harsh, maybe it is. but better you know that there are areas you need to listen (or read) first, before you speak (or write) than for you to make a blunder in front of a client. if they are happy with your work
    they tell 5 people..if they are not happy they tell 10 times that many.

    all that said...glad to see you got your pro status. congrats..
    Wish I could say the same.

    Sorry OP for the interruption of your thread.
    I wish not to discuss this matter on an open forum any longer. If you must, start it back up in a pro section or a pm. Send me a link to your web site I'd like to check that out.
    Always here

  13. #65
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,728
    Quote Originally Posted by efelkey View Post
    I haven't done anything yet. I am looking into a heat audit currently(whatever that is). I do not have $3000 to spend on any option. I have looked at insulation and sealing the attic but seems to be pretty good. The issue, as far as I see it is the heat radiating from the attic or being trapped by the insulation. I have another contractor coming to look at my system next week too. I don't know what to do, since I am not in a position to spend 3 grand. I am not looking for a band aid, but don't have an exact plan at the moment.
    When your neighbor closed off the downstairs return and got desirable results this should be a hint as to what the problem is. There is a circulation problem. The cold air is pooling downstairs, while the hot air is rising upstairs. Heat radiating or leaking through the ceiling or walls is a major assumption for such a new home. I doubt there is insulation or sealing problems that are significant enough to be the cause.

    Assuming insulation and sealing is adequate; the upstairs hot air must be replaced with cold air. This can be done by adding more cold air to the upstairs or by pulling the downstairs air upstairs. Adding more cold supply air upstairs would require a split system or zoning, which equates to dollars.

    Pulling the downstairs air upstairs is what your neighbor did for free. But your neighbor may have caused restriction on the intake of his system. First determine if your upstairs return alone is large enough to supply the unit. If it isn’t, look into adding a second return air upstairs and blocking the downstairs return. This will essentially suck the cool downstairs air up the stairway and “heal” the circulation problem. Your house will then be cooler than your neighbors.

    To say moving, adding, and blocking supply registers is ok to solve a problem and then claim that doing the same to a return is a “band-aid” cannot be adequately explained or defended by anyone here. If they both produce the same result, then they are both valid fixes. Placement of supplies and returns establish the overall circulation of a system.

    Brian

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