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  1. #27
    Join Date
    Jun 2010
    Location
    Philadelphia PA
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    2,190

    Brian, see post 15

    Brian, as the HO said
    .
    Quote:
    Funny thing is my system as designed works great in the winter without doing anything,
    You do seem to find it convenient to not hear/ read what you find inconvenient to your point of view!
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  2. #28
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    Heaterman see post 8

    genduct,

    I am not understanding your argument here.

    Design your next system without high returns, and ballane the supplies precisely to the load, and see how effective that is.
    post 8
    What many of "us" have been trying to share with you (Brian) is:
    a brilliant return duct location will NOT make up for a lack of supply air.

    I happen to agree with a single, high, ducted (no building cavities) return with "jump" or transfer ducts that may be ONE stud space so that the air has a path back to the unit and the difference in zone pressures is less than 2 pascals.

    Remember, there are usually no balance dampers on the return so the air will simply take the path of least resistance.
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  3. #29
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    I hope you are mistaken about this

    Quote Originally Posted by Mike_2008 View Post
    Thanks for your response Heatingman. The upstairs return is right above the downstairs return, so I know the ducts ae directly connected to each other. I did quickly try to partially block the downstairs return and the upstairs return was definitely pulling more air. I assume this is what I want to happen.

    Is their any negative consequences to doing this on permanent basis when using the air conditioning. Any other considerations? Is this common for individuals to do with my type of setup?

    Thanks
    because having these 2 returns common to the same chase is against the code



    And can we stop refering to the hot air that collects on the upper floors as stagnet, this is just the stack effect that we are trying to deal with. Not some toxic siuation!
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  4. #30
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    Brian you said

    Heat load is bad air, A/C air is good air why position a return low in the summer to remove the good air? Why postion it high in the winter to remove the good air? It's mind boggling that this is not understood.
    The addition or removal of HEAT ENERGY does not change air from bad to good or good to bad OR make it stagnant. Your air has not spoiled and needs to be thrown out because it got warmed up

    Having a high return for both seasons will effectively deal with the stack effect that is so annoying and requires changing CFMs to registers with the change of seasons. We do take a small energy penalty in the winter with this approach of a single high return in a multi story home

    I have to agree with you
    It's mind boggling that this is not understood
    How can you misunderstand my simple statements
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  5. #31
    Budman21901: Thanks for your advice on some considerations for closing off the downstairs return. I am not overly dissatisfied with the way the A/C system is working. The upstairs does get cool, but is always 2-4 degrees hotter than downstairs.
    I do have ceiling fans upstairs, so it is comfortable to sleep at night. I am sure I could further cool the upstairs, but I keep the downstairs T-stat at about 74.

    I know the air conditioning system was retrofitted into an existing heating system and the duct work is not ideal. I just want to see if there are any simply things that could be done to further improve the system efficiency. Here on east cost, July and August are the only really hot months, so my primary need is heating.

    genduct: I am no HVAC expert, but the upstairs return is right above the downstairs return, so I am assuming they are connected. The house was built in 1960 and has the original duct work.

  6. #32
    Join Date
    Nov 2007
    Location
    Olympia, Wash.
    Posts
    192
    I had approximately a 5 degree difference between upstairs and downstairs in my four-year-old 3,000 sq. foot 1.5 story home. Attic insulation of R-60, energy efficient windows, yada yada. Single stage Trane XL14i 3.5 ton heat pump with 4 ton indoor coil. Up until this summer, I would close the downstairs vents 50% and that would help about 2 degrees upstairs. I left them wide open in the winter.

    I finally had the real problem fixed last fall. When talking to a third HVAC tech, I explained my system was noisy, in that every time it kicked on I could hear a lot of noise from the single cold air return located upstairs. First tech of the installing company didn't think there was a problem when he did the initial service.

    Second tech of the closer and more convenient company (one I had used in my old home) took measurements, etc. and said my system was "right on the line" at the second year service. I bought a new return grill with flexible louvers and that helped.

    Third tech from the second company last fall listened to the noise, checked the ducting and found the original installing company choked the return to the furnace from 16 inches to 10. That explained why the little orange light kept flashing on the furnace. I couldn't find any literature on that so I figured that was normal for the operation. Nobody said otherwise and the system worked.

    Had the ducting fixed and a second return added downstairs in the ceiling and the entire home is now warmer in the winter, better air flow from the supply registers and now shows only a 1 degree difference between upstairs and downstairs with no adjustments to the downstair registers. And the noise.... there isn't any. No flashing orange lights, either.

    Second company engineers couldn't figure out why the installing company did what it did. Wasn't any reason for it. A little expensive to fix but as I explained to the wife, cheaper than buying a new system seven years from now and still needding to fix the problem.

    Installation is the major factor. Mine was sized right but somebody cut corners on the install or just used what was in the truck to finish the job.
    "Therefore, since we have been justified through faith, we have peace through our Lord Jesus Christ.." (Romans 5:1)

  7. #33
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,388
    Quote Originally Posted by genduct View Post
    Brian, as the HO said
    You do seem to find it convenient to not hear/ read what you find inconvenient to your point of view!
    After rereading post #1 I’m not referring to him as the OP, he dropped out of the conversation after post #1. I’m referring to Cherokee as the OP, post #2. He has a system with “90% of the return on the first floor”. He claims his system heated fine but would not cool the upstairs well. His low return for heating is what allows for this and is exactly inline with what I recommend. I ask that you reread post #2 and explain how Cherokee made those dramatic improvements by balancing/modifying his returns…since return location doesn’t matter to you.

    Quote Originally Posted by genduct View Post
    And can we stop referring to the hot air that collects on the upper floors as stagnant, this is just the stack effect that we are trying to deal with. Not some toxic situation!
    Stack is only one cause of heat gain in summer. Stack cannot be the only cause of that warm air. Heat that penetrates a build, for whatever reason, if not properly mixed with supply air will rise. The same is true with cold supply air, if improperly mixed it will sink to the floor. If you don’t like the word stagnant then call it what you want. I like to call warm air in the summer “bad air”, cold air “good air”. Warm air that is trapped upstairs is stagnant because it is not circulating. Try not to get off track by picking on wording. It’s not “toxic” but it is definitely unwanted.

    Quote Originally Posted by genduct View Post
    The addition or removal of HEAT ENERGY does not change air from bad to good or good to bad OR make it stagnant. Your air has not spoiled and needs to be thrown out because it got warmed up.
    Then call it wanted and unwanted. And, stagnant is correct if it is pooling and non-circulating.

    Having a high return for both seasons will effectively deal with the stack effect that is so annoying and requires changing CFMs to registers with the change of seasons. We do take a small energy penalty in the winter with this approach of a single high return in a multi story home.
    You are alone in this thread by saying it is a “small penalty”. Cherokee’s data says otherwise.

    I have to agree with you
    How can you misunderstand my simple statements
    We aren’t misunderstanding statements; you seem to not understand simply physics of air density.

    The problem with this conflict of views is that for you to admit or grasp that high single returns (especially in two story homes) strongly favor the cooling side and screw the heating side you’d also have to admit that you screwed a lot of your customers over the years with these attic installations. That’s a hard pill to swallow. You obviously don’t like me making these claims about these installations but as long as people like Cherokee keep coming forward with hard evidence that they are wasteful and inefficient, I will keep backing them up.

    And, your bone is not with me, it should be with Cherokee this time. He makes the claim with data that he fixed efficiency and temp gradients with return modifications.

  8. #34
    Sorry guys I have been out of the conversation for awhile. My account got locked as I switched to Fios from comcast and they don't keep your email operational for very long. Anyway, I can still confirm my system is running fantastic now. Today is not a good day to prove the performance since the cooling load is so low, but the temperature is exactly 75 on both floors. Normally now it is 2 degrees difference, but sometimes one. I am very happy. I don't recommend anyone totally block off the downstairs registers. Mine were in series, so I left 10% open on the bottom floor, and I probably could have left more open. The key is that the system was not designed properly, and this "adjustment" is just helping to pull adequate return air from upstairs. Physics is doing the rest. You do definitely need to make sure you are not lowering the CFM too much by increasing the DP a bit on the suction side. I will try to see if I can do any screen captures on mac to show the data, but it is dramatic to say the least. Anyone know how to capture screens on a mac? I just got my mac a month or so ago.

  9. #35
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
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    3,304
    Quote Originally Posted by cherokee180c View Post
    Sorry guys I have been out of the conversation for awhile. My account got locked as I switched to Fios from comcast and they don't keep your email operational for very long. Anyway, I can still confirm my system is running fantastic now. Today is not a good day to prove the performance since the cooling load is so low, but the temperature is exactly 75 on both floors. Normally now it is 2 degrees difference, but sometimes one. I am very happy. I don't recommend anyone totally block off the downstairs registers. Mine were in series, so I left 10% open on the bottom floor, and I probably could have left more open. The key is that the system was not designed properly, and this "adjustment" is just helping to pull adequate return air from upstairs. Physics is doing the rest. You do definitely need to make sure you are not lowering the CFM too much by increasing the DP a bit on the suction side. I will try to see if I can do any screen captures on mac to show the data, but it is dramatic to say the least. Anyone know how to capture screens on a mac? I just got my mac a month or so ago.
    I appreciate you telling us of your success. I was prepared to be skeptical, but as long as you don't use words like "miracle cure" I am eager to hear what works for you. Also, I am adverse to hearing how the whole profession is hiding what works, because that is nobody's intent.

    Best wishes -- Pstu

  10. #36
    OK, here is the data. I purposely waited to a similar very hot week to pull the data for the after. In fact there was a 99 deg and a 100 deg day in the second week.

    Before Week Mean High Temp = 91.1 Ave Daily Use = 60.97 KWhr Max=82.42 kWhr
    May 26 41.45 kWhr Temp 91/66
    27 44.28 kWhr Temp 85/66
    28 51.37 kWhr Temp 84/64
    29 82.42 kWhr Temp 85/68
    30 71.76 kWhr Temp 98/70
    31 63.75 kWhr Temp 97/72
    01 71.76 kWhr Temp 98/73

    After Week Mean High Temp = 90.3 Ave Daily Use = 41.72 kWh Max = 56.92kWhr
    June 07 31.55 kWhr Temp 90/60
    08 47.74 kWhr Temp 99/68
    09 49.71kWhr Temp 100/71
    10 43.23kWhr Temp 91/69
    11 56.92kWhr Temp 87/71
    12 43.90kWhr Temp 87/68
    13 18.96kWhr Temp 78/62
    Attached Images Attached Images    

  11. #37
    The problem is people get too emotional. I am a mechanical engineer and perfectly capable of troubleshooting these kinds of issues as I also have experience designing industrial dust collection hoods and air conveying systems. There are a lot of specifics that apply here, Open foyer house, very efficient insulation/air tightness, only three air returns on the first 2 floors, 2 of which were in series and the bottom floor was short circuiting the upper floor return, etc. The only reason I posted this, was because I believe a lot of other people are dealing with houses where the HVAC was never Engineered correctly. It is amazing how the system is like an entirely new system to me with some simple changes to balance the airflow.

    Oh, yea, I forgot to mention that the second week has the new thermostat installed as well and I am now running the system much more at night as it is controlling from the remote sensor to exactly 75 degrees at night. I can now see the system cycling all night long on graphs, where it was off most of the night in the first set of data. Again my recovery time from an 85 degree setback temperature to 75 degrees is now under 2 hours when it was over 5 before.

  12. #38
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    I am convinced that HVAC design and installation actually deserves to be called an engineering job. There seems to be no organization, no trade union or other, which is able to set standards (which will be followed) and ensure the job is done right. ACCA sets standards but we see how they are honored mainly in the breach.

    Best wishes -- Pstu

  13. #39
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,388
    Quote Originally Posted by cherokee180c View Post
    The key is that the system was not designed properly, and this "adjustment" is just helping to pull adequate return air from upstairs. Physics is doing the rest. …but it is dramatic to say the least.
    Quote Originally Posted by cherokee180c View Post
    The problem is people get too emotional. I am a mechanical engineer and perfectly capable of troubleshooting these kinds of issues…

    A little background on me is that I too come from a family of Engineers, (two mechanical and one chemical). This subject was discussed by us in detail and is understood very well. I also did the change you just did on three houses. After being absolutely amazed at the findings I brought my discoveries here to this forum. They were by most part poo-pooed. That is why it is nice to see someone come up with the same findings as I did and has the ability to convey them.

    There are a lot of specifics that apply here, Open foyer house, very efficient insulation/air tightness, only three air returns on the first 2 floors, 2 of which were in series and the bottom floor was short circuiting the upper floor return, etc. The only reason I posted this, was because I believe a lot of other people are dealing with houses where the HVAC was never engineered correctly. It is amazing how the system is like an entirely new system to me with some simple changes to balance the airflow.

    Again my recovery time from an 85 degree setback temperature to 75 degrees is now under 2 hours when it was over 5 before.
    That is a 60% improvement. To me that is phenomenal…I got similar results.

    You and I came here for the same reason. We wanted to share with the industry that incorrect location and imbalanced returns can “short circuit” air paths. If more care was put into return location more people could realize similar improvements as you did. But nobody is teaching the industry about this. There is way too much focus on the supply side and little to none on returns.

    Excuse me if I get a little “emotional” about it, I’ve been trying to get my point across for three years now. I just imagine all the people your installer and others like him screwed over the years. It's time for it to stop.

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