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  1. #53
    Join Date
    Apr 2011
    Location
    midwest (st.louis) area
    Posts
    11

    Need Help

    Let me start by saying I live in the St. Louis MO. area it is very hot and Humid here . I have been in my home since 2001 , when it was built .
    As far as i can remember (which isnt tooo long ) the A.C. seemed to keep the house cooler than what it is now , I have a 1600sq. ft 2 story home and basement , which is where my furnace is 75,000 btu's . the A.C. unit is a Comfortmaker as is the furnace , 3 ton unit . The A.C. unit outside is 9 years old not like the rrest of the unit , but that is another story. I keep the unit free of any dirt or debri . the infide filter is changed religously every month.
    The past 4 years or so the unit seems like it just runs and runs and the house still gets warm . the east side is my sons room and kitchen d-stairs , and the stairwell his room is at 80 degrees when it is hot out like today 90 this morning and will stay that way all day we have a portable ac in our b-room which runs ALL the time n-w corner of house. I have had Dixon's HVAC come out and look at it for the past 3 years added a little freon once he checked td's superheat and all lookes fine , when the sun sets our livingroom will get 80 dregrees also , I dont know why this has been getting eorse over the paast few years but it is about to drive me nuts , we keep all doors and windows shut also . We have a attached garage with our broom over it 2 years ago i noticed water stains in the ceiling , come to find out there was NO insul. in the rafters where the cold air vent was and it started sweating , But why would this start now and not from the time the house was built .. i hope someone could shed some new light on this for me as i am at wits frickkin end . Aslo have cold air returns in all upstairs rooms . Thanks

  2. #54
    I am not sure about the specifics in your house, but it sounds a lot like infiltration and insulation problems. There are a ton of things that can go wrong. Do you have recessed lights on the second floor, etc. I have a cathedral ceiling in my master bedroom that is also half over my garage. I had 2 rows of insulation in the walls fall down as well as ALL the fiberglass blown insulation blow off my ceiling of my walk in closet so I had an R value of 1. Both of these was caused by the stupid egg carton wind deflectors breaking and high winds moving the insulation in my Attic. I highly recommend paying for a home energy audit where the company will come in and use an IR gun in the house and give you a full report including thermal pictures of the problem areas. They will also measure air infiltration and prioritize the work for you. These companies can set you up with contractors if needed. I paid $500 a few years ago, but I have seen them on sale for around $350 lately. You will not believe what they discover and if you are handy you can do almost all the fixes yourself for little cost. I fixed the wall insulation and then wrapped again in the attic with R-19 as well as added another R-30 of cellulose to my attic that fixed my issues.

  3. #55
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,541
    Quote Originally Posted by cherokee180c View Post
    I look at it this way, we can all learn from each other. Some of this is basic physics and no matter what your "beliefs" the data will always tell the truth. I certainly am not an expert at HVAC, but I do have a very good heat transfer and power plant thermodynamics background so I can understand all the concepts. I still tend to get specific answers from the pros, but put their answers through the filter to separate facts from opinion. It is all good.
    I have also learned a lot from the pros and homeowners here and am appreciative of that. We all can learn from one another. But, the data you are coming forward with has been highly refuted by hundreds, if not thousands of back and forth posts. There are at twenty to thirty pros here that are choosing to stay out of this discussion now, as Xavier noted, that do not believe return location has any significant impact on system efficiency or comfort. They are most likely the type that designed your system and will continue designing that way…with little understanding of general airflow patterns. You come here to share a bit of awareness but believe me, it is falling on deaf ears. Have they asked you a single question yet about your findings? No!

    Threads like this help me understand the nature of posters here. They are not interested in how you or Xavier made your systems more efficient. If other “pros” do not respect your approach, they will not either. Or, maybe it’s just over their heads, I’m not sure.

  4. #56
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by Brian GC View Post
    ... Or, maybe it’s just over their heads, I’m not sure.
    I am sure and you are right. Most duct systems are poorly designed because the techs tend to be focused on the equipment.
    • 2 story homes are typically a problem without zoning.
    • If the duct system is well designed a 2 story home can be made to work with major manual adustements between the heating and cooling seasons.
    • Both the return and supply ducts must be correctly designed.
    • The supply system is the most important because no amount of return can overcome little or no supply air.
    • The return duct sizing and locations matter, but to a lesser extent.

    Consider a hot room upstairs in the summertime with no supply duct. Even if all of the return air came from that area, the air moving up the stairwell will be at the 75°F temperature of the downstairs zone.

    Now consider the same hot room upstairs in the summertime with no return duct upstairs. If there is enough 55°F supply air delivered and distributed, the stairwell will work just fine as a return pathway and the space will be cool.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  5. #57
    Now consider the same hot room upstairs in the summertime with no return duct upstairs. If there is enough 55°F supply air delivered and distributed, the stairwell will work just fine as a return pathway and the space will be cool.
    You have some very good points above and I agree with everything you wrote EXCEPT the statement above, which is 100% wrong. The problem you don't understand is that it does not just magically get delivered and evenly distributed. You get some mixing out of the supply registers and then normal physics takes over and cold air sinks and hot air rises. My house had the exact same condition you describe with adequate supply vents and a 90% crippled air return on the 2nd floor. You actually said no return in your claim. This led to all the cold air staying near the floor level and exiting quickly down the stairs in my open foyer (nothing but a huge air duct) to the first floor. I should use the words "pulled downstairs" as the return duct downstairs was doing just that. The result was a perfect stack effect with hot stagnent air trapped above 3' as well as an A/C system cooling already cooled air leading to 30% more energy being spent on A/C. Try to get that kind of return on investment with a 20SEER $10k system added onto an already screwed up duct system.

  6. #58
    Quote Originally Posted by Brian GC View Post
    I have also learned a lot from the pros and homeowners here and am appreciative of that. We all can learn from one another. But, the data you are coming forward with has been highly refuted by hundreds, if not thousands of back and forth posts. There are at twenty to thirty pros here that are choosing to stay out of this discussion now, as Xavier noted, that do not believe return location has any significant impact on system efficiency or comfort. They are most likely the type that designed your system and will continue designing that way…with little understanding of general airflow patterns. You come here to share a bit of awareness but believe me, it is falling on deaf ears. Have they asked you a single question yet about your findings? No!

    Threads like this help me understand the nature of posters here. They are not interested in how you or Xavier made your systems more efficient. If other “pros” do not respect your approach, they will not either. Or, maybe it’s just over their heads, I’m not sure.
    Obviously I am not privy to the history, so I will refrain from comments on such. I will honestly answer any questions and provide the data for anyone looking to truly learn something. What you have to understand in anything is to always follow the money. People who have a vested interest in selling new equipment are never going to be open to the fact that you can make far more % improvements by simple modifications to the home at very little cost. Only after these improvements are done, should you even consider new HE equipment. Even after that, my calculations show that there is absolutely no payback at less than 20years to upgrade your units if they are properly functioning 10SEER or above units. My 12SEER Trane unit would only save a MAXIMUM of $132/cooling season to move to a 16SEER unit. Now figure the payback on a $10K capital expenditure. Bottom line is fix your house to prepare, and then replace with the Highest efficiency that is cost effective when your unit breaks.

  7. #59
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,944
    Quote Originally Posted by cherokee180c View Post
    You have some very good points above and I agree with everything you wrote EXCEPT the statement above, which is 100% wrong. The problem you don't understand is that it does not just magically get delivered and evenly distributed. You get some mixing out of the supply registers and then normal physics takes over and cold air sinks and hot air rises. My house had the exact same condition you describe with adequate supply vents and a 90% crippled air return on the 2nd floor. You actually said no return in your claim. This led to all the cold air staying near the floor level and exiting quickly down the stairs in my open foyer (nothing but a huge air duct) to the first floor. I should use the words "pulled downstairs" as the return duct downstairs was doing just that. The result was a perfect stack effect with hot stagnent air trapped above 3' as well as an A/C system cooling already cooled air leading to 30% more energy being spent on A/C. Try to get that kind of return on investment with a 20SEER $10k system added onto an already screwed up duct system.
    I DO agree with his statement above, as my house is exactly that way. I have quite the breeze coming down the stairway, but there is no way to get a return up. However, I have a great distribution system with big ducts going up. I don't have a stratification problem with my house with no returns upstairs.

    Part 2 of my post

    I come from a similar background as you-coming from a power plant-heat transfer background. I would love to be able to put many returns in houses, but the space isn't there and most of the time they don't want to spend money on the upgrade to multiple returns.

    If you size the supplies right to mix the air using the engineering data from the grill manufacturer-you don't need no fancy high and low returns....but you do need a return.

  8. #60
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    Cherokee, have you considered the variables in air mixing? ACCA Manual T has something to say about that, which is unread and unknown by Brian and X. Each of them adopts a scolding manner, which partially explain reluctance to talk further with them. I have tried to correspond with X off-line in an effort to get to the actual logic behind his statements and claims. After several months of hearing fuzzy claims I have concluded there cannot be a logical conversation with him. Brian is better IMO than that.

    Cherokee, one element I would offer to a logical discussion is: if return location makes much of a difference in efficiency, then it should be no mystery at all to measure the temperature at each proposed location. Is the measured difference plausible as an explanation for the results claimed? If you do not measure a substantial difference then you have not supported your thesis.

    If there IS a substantial difference then I would like to hear open minded consideration of all ways to deal with that, not just the single option of relocating the return. In a house with ceiling fans I do not think the discussion needs to continue.

    Hope this helps -- Pstu

  9. #61
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by cherokee180c View Post
    You have some very good points above and I agree with everything you wrote EXCEPT the statement above, which is 100% wrong. The problem you don't understand is that it does not just magically get delivered and evenly distributed. You get some mixing out of the supply registers and then normal physics takes over and cold air sinks and hot air rises. When the fan is off, stratification due to the differing densities of cold air and warm air takes over. However when the fan is on the fan driven mixing of the air overwhelms the density effect. My house had the exact same condition you describe with adequate supply vents and a 90% crippled air return on the 2nd floor. You actually said no return in your claim. This led to all the cold air staying near the floor level and exiting quickly down the stairs in my open foyer (nothing but a huge air duct) to the first floor. This sounds as though the supply grilles are in the floor or at the wall near the floor. In addition, the supply air may have lacked the velocity to throw or push the air up into the room beyond the 3 foot level. In that case a high return vent would make up for the poor volume and velocity of the supply air. The choice of grilles on the supply duct may well be a factor, especially if the grilles are mounted low on the walls. I should use the words "pulled downstairs" as the return duct downstairs was doing just that. The result was a perfect stack Stratification rather than stack, effect with hot stagnent air trapped above 3' as well as an A/C system cooling already cooled air leading to 30% more energy being spent on A/C. Try to get that kind of return on investment with a 20SEER $10k system added onto an already screwed up duct system.
    What you did obviously worked. What I say, with proper design of the supply duct and grille selection, would work equally as well. I would choose a one-way ceiling grille with curved blades to deliver air upward from a low sidewall location. The air would be directed up instead of outward into the room. Post 59 confirms my position on the supply ducts but your more complete description of the Stratification problem while running needed further explanation.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  10. #62
    My supply registers are actually at floor level and I do have a ceiling fan in my master bedroom that mixed the air. I still ended up with a 6 degree temperature difference between that bedroom and directly below it in the open foyer. I am sorry to disagree with you guys a bit, but a single ceiling fan in a master bedroom with a cathedral ceiling is not going to adequately mix air so the density effect with no return register does not exist. This was proven by my 6 degree temperature differential, which is now 2 degrees since I have tripled (estimate) the return air flow from the 2nd floor hallway return which is located up high in the hallway. The ceiling fan, does provide considerable comfort from the evaporation effect of moving air over the skin. I could not even imagine how bad my problem would have been with no return at all on the second floor.

    I don't doubt that is I had double the airflow from the supply registers upstairs that the problem would be reduced, as my parents have that case with an isolated A/C system upstairs that delivers tons of cold air, but a normal open foyer house where they have not zoned the upstairs properly and have not designed the house a bit around a proper HVAC system will have these types of problems.

  11. #63
    Join Date
    Dec 2000
    Location
    Michigan
    Posts
    724

    Hmm Air in a Bottle!

    First the great news, the part I designed for my Jag works great.

    I also updated the alternator to a new design that I discussed with someone who builds and repairs them (Expert) and “we” came up with a Chevy alternator that we/he modified. Last night after talking with an HVAC poster on how I can cool my home with only 2 tons, I went cruising to confirm what I had done WORKS!

    The car is running great for being 46!

    The point of this story is I do and have done what I post! Not sure how many posters can make that claim.

    PTSU if you remember many years ago when you first posted with your question, I stated you had leaking duct work in non-conditioned spaces. (this was before it bacame a popular respnse on HVAC!) Since that time you have spent time and money trying to better understand your home. You also know that my son and I redid his home in Texas to a “X” design and reduced his energy costs significantly and improved his IAQ. I have sent you the drawings of the duct design, but I am not sure you understand them as they do not agree with manual D. Finally, not sure what your career was, but it is clear it was not in negotiations, because when you (& Carnak) turn to personal attacks it is a sign you have lost the discussion. You may want to reread your posts. By the way, what size is your AC?

    Lynn, to explain your statements, have you ever taken a bath and after a short while the water cooled off? So you turn on the faucet (any DESIGN you want!) and out comes all this hot water, BUT how long does it take for the NEW HOT WATER to get to the other end of the tub and raise the temperature? With this process you are constantly “averaging” the temperature. Now imagine you opened a drain on the other side of the faucet and let the “OLD” cold water out. Would the temperature change more quickly in the tub?

    Furthermore, while the air is going down the stairs it is raising the temperature in that area, -- less efficient. Also, it is extremely difficult to blow/push air into a bottle no matter what the nozzle looks like

    I suggest that when a poster recommends a solution they should include if they have used it or are merely quoting from the manufacturer’s ad or stating their opinion. How many of you when you go to the Doctor ask him “Have you done this before”, I DO!

    Time for cruising with the top down so I can get better air exchange; in and OUT!

    X
    The quality of my performance, sometimes depends on the quality of my audience.
    Imitation (Plagiarism) is the best compliment one can get -- "Open A Window"

    To improve Indoor Air Quality: Control Indoor Air QUANTITY = "I.A.Q.Q."

  12. #64
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by Xavier View Post
    ...Lynn, to explain your statements, have you ever taken a bath and after a short while the water cooled off? So you turn on the faucet (any DESIGN you want!) and out comes all this hot water, BUT how long does it take for the NEW HOT WATER to get to the other end of the tub and raise the temperature? With this process you are constantly “averaging” the temperature. Now imagine you opened a drain on the other side of the faucet and let the “OLD” cold water out. Would the temperature change more quickly in the tub? Analogies are fickle. I would compare it to a whirlpool spa rather than a bathtub because the mixing is forced by a pump.

    Furthermore, while the air is going down the stairs it is Only if the air in the upper floor was warmer than the lower floor. raising the temperature in that area, -- less efficient Neutral efficiency. . Also, it is extremely difficult to blow/push air into a bottle no matter what the nozzle looks like The upper floor has an open stairwell usually and air flows freely down the stairwell as the OP noted. However, if the stairwell is sealed of with a door, you are correct about pushing air into a bottle as an analogy....
    I have plenty of field experience on airflow and design. I did not object to the high return. It worked for the OP and I acknowledged that it worked. "There is more than one way to skin a cat." Another analogy, sorry.

    Note that I was correct about the supply grilles being at floor level (post 62). The OP did not confirm that they are in the side wall and that the air is directed out into the room instead of up along the wall. His description of stratification is classic for a poor choice of grille and/or grille location.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  13. #65
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,541
    Cherokee,
    You have a very good understanding of the subject because of your background and the fact that you have seen it work. I believe it will be hard to dissuade you now.

    Lyn,
    Perfect air distribution is very effective as you point out but how often do you see supply registers in hallways or foyers circulating that air? These areas are often large “return ducts” that “pull” the densest air downstairs (during cooling when return is downstairs). Of course anything can be overcome by more supply volume and velocity but hat comes at an energy price. Cherokee overcame his problem without increasing volume, velocity or changing supply location or grille selection.

    Mixing supply air is good but it is what Xavier called “averaging”. His bathtub example showed this. If hot water was inputted into one side of the tub and the cooler water was removed from the other side of the tub it would heat faster and more efficiently than if you inputted and removed from random locations in the tub and stirred the water.

    Pstu,
    We all have different writing styles and levels of frustration. IMO you should interpret and respond a little less personally and stick to the subject, similar to a classroom.

    Lyn has seen his approach work and Cherokee has seen his method work. They both will obviously cool a house fairly evenly. The question is which does it with more efficiency and less energy consumption?

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