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  1. #40
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    Quote Originally Posted by pstu View Post
    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 averse to hearing how the whole profession is hiding what works, because that is nobody's intent.

    Best wishes -- Pstu
    A 60 % savings with no changes to the unit or structure is very impressive. Maybe not quite a “miracle”, but close to it. And, I never said the “the whole profession is hiding what works". I said they are mainly unaware of these airflow characteristics and how they relate to system efficiency.

  2. #41
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    Dec 2004
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    Chicago area
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    1,438
    [QUOTE

    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.[/QUOTE]

    If you want things to be built and designed better, the solution is simple. Stop taking the lowest bidder, or at the very least, even the playing field by having a engineer provide a complete design spec.

    Instead all engineering of heating/cooling systems is put on the lap of the hvac guy who is expected to do it for free due the chance of being rewarded work. No other industry is like that. A carpenter has a complete job drawing of every detail, down to cut angle. The plumber and electrician are told exactly what needs to go where. The best that is ever done for the heating guy is where he can cram the furnace.

    It totally blows my mind how little consumers care for the comfort of their most expensive possession, their home.

    One of my biggest complaints about consumers today is what is found to be acceptable. As long as it is cheap, it must be good.

    People like me, that do things right, are not acceptable because we won't work for free and therefor are quickly being driven out of the industry.

    There is a reason these problems don't exist in the massive scale of today in houses built before 1935. 30 percent of construction budget used to be heating. In recent history, its been closer to 5%.

  3. #42
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    Mar 2008
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    Quote Originally Posted by cherokee180c View Post
    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
    Cherokee,
    Thank you for showing your data; it is an average of 32% savings in overall electric usage. Truly remarkable!

    I have a question. You say you made two changes to your current supply and return setup.

    1) Closed some of the downstairs supplies to force more supply air upstairs.

    2) Restricted/closed a portion of the downstairs return to force the upstairs returns to draw more air.

    Did you ever do these changes separately to determine which had the greater influence?

    Another thing to consider: Each of these changes probably reduced cfms, yet a significant improvement resulted anyway.

  4. #43
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    Jun 2010
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    Philadelphia PA
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    2,159

    There is no one approach prescribed by ACCA

    Quote Originally Posted by pstu View Post
    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
    Clearly there are differences of opinion on the approach. Might we all agree that the air needs "a way back to the unit"?
    Beyond that, some of us believe that "air problems" can't be solved with return duct locations ONLY. That, in fact, you first need supply air delivered to the space to maintain set point.
    That being said, some ( I'm in that camp) believe that the benefit of a single high return is that it helps deal with the "stack effect" that is so problematic in summer as well as winter.

    It continues to amaze me how anyone can find a flaw in those simple statements. But some do. Go and figure!
    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. #44
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    heatingman' You make a good point!

    If you want things to be built and designed better, the solution is simple. Stop taking the lowest bidder, or at the very least, even the playing field by having a engineer provide a complete design spec.
    Wouldn't be great if there was an initial design drawing so that you would get apples to apples.
    Thing is, even my Plan and Spec commercial jobs are Design-Build. We are finishing a 20K office space converted warehouse and any resemblance between the original design and what we built and installed was purely coincidental. The Rooftop changed manufacturer and there were several errors along with clearance conflicts the engineer didn't begin to accomodate.
    My job description is putting 10 pounds of "stuff" into a 5 pound bag! I can get 7 pounds, but can't get 10!
    The problem is that for the past 30 years, HVAC training has focused on the BOX and not the SYSTEM ( the stuff hanging off the box that delivers the comfort. Most HVAC programs don't have blueprint reading for instance let alone a meaningful Airflow or duct design/sizing requirement. So there you have it.
    Contractors are installing bad jobs out of ignorance not malice. They don't know any better IMO
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  6. #45
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    Quote Originally Posted by genduct View Post
    Might we all agree that the air needs "a way back to the unit"?
    No argument there. But as Cherokee discovered and has shown through exact measurements, it matters which air in the house is sent back. He was sending back the downstairs air during A/C and it hindered the function and efficiency of his system. That is the point. It sent cool downstairs air back to the handler while allowing the hotter air to pool upstairs. He called it "short circuiting".

    I on the other hand have seen high returns during heating do the opposite. They send the warmer upstairs air back to the handler while allowing the cooler air to pool downstairs.

    Beyond that, some of us believe that "air problems" can't be solved with return duct locations ONLY. That, in fact, you first need supply air delivered to the space to maintain set point.
    Cherokee redirected supply air upstairs but he placed a great emphasis on how he drew more return from upstairs. By doing this he has reached setpoint 60% faster (5hrs to 2hrs). So reaching setpoint and reducing temp gradients is not only accomplished with supply air delivery.

    That being said, some (I’m in that camp) believe that the benefit of a single high return is that it helps deal with the "stack effect" that is so problematic in summer as well as winter.
    You have a point that it might reduce stack effect by lowering pressure up high and increasing pressure down low in the structure. But stack effect cannot exist without temp gradients and a way for the air to leak out of the structure. Since high return are not good for heating because they short circuit the air path by drawing the warmest air back to the handler, it increases temp gradients…exactly what causes stack effect. If you want to reduce stack, plug the holes up high.

    It continues to amaze me how anyone can find a flaw in those simple statements. But some do. Go and figure!
    Generally speaking what you say is true. But a closer look shows there is more to it.

  7. #46
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    Jun 2010
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    Philadelphia PA
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    I am as exhausted as is this subject

    I have said about all I want to say.

    PS, just because I don't agree with your version of Physics doesn't mean I don't understand the underlying science that makes this stuff work!

    Let's just agree to disagree without being disagreeable
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  8. #47

    re

    Quote Originally Posted by Brian GC View Post
    Cherokee,
    Thank you for showing your data; it is an average of 32% savings in overall electric usage. Truly remarkable!

    I have a question. You say you made two changes to your current supply and return setup.

    1) Closed some of the downstairs supplies to force more supply air upstairs.

    2) Restricted/closed a portion of the downstairs return to force the upstairs returns to draw more air.

    Did you ever do these changes separately to determine which had the greater influence?

    Another thing to consider: Each of these changes probably reduced cfms, yet a significant improvement resulted anyway.
    Sorry, I didn't check back on this thread in a while.

    1. No, I did that originally and realized I raised the Static Pressure too much on the system and dropped CFM significantly. I originally did this by closing off most of the first floor returns. After thinking a bit more about the issue, I realized what I had done and then developed the improved strategy. The key was to realize I only really needed the upstairs temperature to be 75 from 10pm to 5am. I then opened up all the downstairs vents and installed the Activent's that created two seperate "poor man's" zones on the first floor. They are temperature controlled and I set them up to be 1 deg under the 75 degree 1st floor setpoint. This way all the downstairs vents are open all day long and never close. Only at night when I am controlling to 75 upstairs on the new Honeywell Prestige remote, do the Activents close after the downstairs over cools (below 74) forcing more CFM upstairs. Only 5 vents on the first floor are using the Activents (2 family room) and (1 dining room +2 Living room). All the other vents in the middle of the house on the first floor are wide open. Remember, I wasn't really running the system at all at night before, hense the complaints from the wife as she wakes up multiple times per night. I just slept through any previous issues.

    2. Yes, I closed 90% of the first floor air return that was in series with my upstairs air return. I attribute this to +90% of my savings as I probably trippled the air pulled through the upstairs return. I also don't think I dropped CFM very much from the slight increase in SP, although some drop had to have occurred. Unfortunately I never tracked the effects seperately, but I am pretty sure the Activents don't save me over 10% of the total, as the real major issue was related to the stack effect.

    As another update, I am one day away from my full one month bill with the new changes. My TED5000 energy monitor is showing I am on schedule to have the lowest July energy bill since I finished my basement 5 years ago and the second lowest ever for the 7 years I have data. I added a ton of energy using stuff (projector, extra refrigerator, a ton of can lights, extra A/V system, etc) in my basement. I am interested to see how well the TED5000 is calibrated as well, although the savings I measured was from the same device, so it is real, even if calibration is slightly off.

    One last thing. I think my system may be short cycling a bit now after it recovers from the daily setback. This is probably due to all the energy efficiency improvements I have made. I am looking long term to upgrade to a 2 stage unit once my single stage dies, but I may want it sized down to 3 ton now or lower after a proper manual J or other more modern analysis tool looks at the data and engineering again.

  9. #48
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    Mar 2008
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    Quote Originally Posted by cherokee180c View Post
    Sorry, I didn't check back on this thread in a while.

    1. No, I did that originally and realized I raised the Static Pressure too much on the system and dropped CFM significantly. I originally did this by closing off most of the first floor returns. After thinking a bit more about the issue, I realized what I had done and then developed the improved strategy. The key was to realize I only really needed the upstairs temperature to be 75 from 10pm to 5am. I then opened up all the downstairs vents and installed the Activent's that created two separate "poor man's" zones on the first floor. They are temperature controlled and I set them up to be 1 deg under the 75 degree 1st floor set point. This way all the downstairs vents are open all day long and never close. Only at night when I am controlling to 75 upstairs on the new Honeywell Prestige remote, do the Activents close after the downstairs over cools (below 74) forcing more CFM upstairs. Only 5 vents on the first floor are using the Activents (2 family room) and (1 dining room +2 Living room). All the other vents in the middle of the house on the first floor are wide open. Remember, I wasn't really running the system at all at night before, hence the complaints from the wife as she wakes up multiple times per night. I just slept through any previous issues.

    2. Yes, I closed 90% of the first floor air return that was in series with my upstairs air return. I attribute this to +90% of my savings as I probably tripled the air pulled through the upstairs return. I also don't think I dropped CFM very much from the slight increase in SP, although some drop had to have occurred. Unfortunately I never tracked the effects separately, but I am pretty sure the Activents don't save me over 10% of the total, as the real major issue was related to the stack effect.

    As another update, I am one day away from my full one month bill with the new changes. My TED5000 energy monitor is showing I am on schedule to have the lowest July energy bill since I finished my basement 5 years ago and the second lowest ever for the 7 years I have data. I added a ton of energy using stuff (projector, extra refrigerator, a ton of can lights, extra A/V system, etc) in my basement. I am interested to see how well the TED5000 is calibrated as well, although the savings I measured was from the same device, so it is real, even if calibration is slightly off.

    One last thing. I think my system may be short cycling a bit now after it recovers from the daily setback. This is probably due to all the energy efficiency improvements I have made. I am looking long term to upgrade to a 2 stage unit once my single stage dies, but I may want it sized down to 3 ton now or lower after a proper manual J or other more modern analysis tool looks at the data and engineering again.
    Thank you for the response. You seem to be very observant of your situation and have taken good records.

    As you have probably gathered I came from the understanding that return location, along with balancing each return, can contribute to or hinder the performance of a system. There are many here that say return location has little-to-no bearing on system performance as long it allows a “path back to the air handler”. I do not agree and it is not that simple. What I believe you are saying, and have measured, is that it matters a great deal WHAT air is being pulled back to the handler. In your case it’s the removal of the hot, stagnant upstairs air that has made your system more efficient.

    Correct me if I am wrong but are you saying that by tripling your upstairs return flow rate it has helped reach setpoint 60% faster…from 5hrs to 2hrs? If so, this is phenomenal and should resonate loudly on this site. This is a widely contested theory here and it should be at least challenged by some of the many detractors of this theory. If they still think return location is next to irrelevant outside of providing a “path back to the air handler” this should provide an awakening.

    I have been saying that return location has a great deal of importance in establishing general airflow patterns within a structure. There is more to it than just pumping more conditioned air into a space to obtain setpoints and comfort. Knowing where the conditioned air and heat gain/loss gathers in a structure is an important part of the design that is often misunderstood. ...and the customer pays dearly for this lack of knowledge.

  10. #49

    Re

    I think you both may be correct. In general the return path may not matter very much in a well designed home with multiple returns. However, in a situation with only a few returns, any design flaw (ie two of the main returns in series and not balanced) could have a huge effect! I also cut in a return in the basement at floor level (vents in ceiling) when I finished the basement and it made a huge improvement as heat was hanging around ceiling and then going to the first floor return. Now basement is nicely balanced and not as freezing in the summer either.

  11. #50
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    Quote Originally Posted by cherokee180c View Post
    I think you both may be correct. In general the return path may not matter very much in a well designed home with multiple returns. However, in a situation with only a few returns, any design flaw (ie two of the main returns in series and not balanced) could have a huge effect!
    You are correct. The more returns throughout the house the less any one return can remove conditioned air or allow pooling of “bad air”. But, what I see more of is one central return where the contractor knows nothing about its pitfalls. When areas of the house remain cold or hot they will recommend zoning. This just pumps more conditioned air into that area instead of just removing it and pulling the already conditioned air toward it…exactly what you have done.

    You have used return location to severely affect general airflow patterns, remove “bad air” and improve comfort and efficiency, something many here say is impossible.

    I also cut in a return in the basement at floor level (vents in ceiling) when I finished the basement and it made a huge improvement as heat was hanging around ceiling and then going to the first floor return. Now basement is nicely balanced and not as freezing in the summer either.
    What you did to your basement makes a lot of sense. Cold conditioned air was flowing down the basement stairwell and pooling on the basement floor. As this air flowed down there it pushed the warmer air out of the basement and into the low returns of the first floor. By adding a return down at basement floor level it removed the coldest air and did not allow the warmer air to leave the basement.

    What you have done is played with return location and made substantial improvements to comfort and efficiency. Know that this is not taught within the HVAC industry as far as my research shows and definitely not known by many of the “pros” on this site. You learned it because of your “engineering mindset”. Maybe the so called ‘HVAC scientists’ will figure it out someday before we piss away all of our natural resources and go broke in the process.

  12. #51
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    Dec 2000
    Location
    Michigan
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    724

    Hmm HVAC Return Design

    Hi Brian, how have you been?

    Today I am waiting for some custom parts that I designed for my Jag to be done by a tool and die shop, so I checked in on HVAC.

    Thanks for carrying the “torch” (Xavier’s High and Low ‘Louvered' Return System) but as this long thread still shows, there is still not an understanding on how a home works.

    As you know, we walk the talk and have the data to support our “designs” unlike most posters who either state their opinion or are not willing to do the job correctly.

    The only way to determine if the HVAC system is designed/sized correctly is to monitor it when the design assumptions are met. I have stated for years that my HVAC system for my 3,500 sq. ft. two story home in full sun is 48,000 BTU’s for heating and 2 tons of AC for cooling, and no one has ever said that is “great” (or Impossible), or better yet, how did you do that X?

    (NOTE this sizing is INCONSISTENT with most of today's HVAC Expert assumptions)

    This Monday the weather is forecast to be 95 F, the design assumptions I used for my system, therefore, it should run continuously at that temperature and hold the inside temp at 75 F at 45% RH. If the unit still cycles at 75, I will lower the temp to see how low it can go!

    I will post the time and temperatures (DATA) next week to again prove our understanding/designs work!

    I have posted similar data to prove our designs work but the majority of the “pros” just ignore my posts and continue with their “band-aids” (Zoning, fancy registers, cut the bottom of the doors off, by-pass/cheaters, high tech stats, etc.)!

    Lets keep posting so perhaps, homeowners will request a better system, just in case Al Gore is Correct!
    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."

  13. #52
    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.

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