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  1. #66
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    Aug 2003
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    Regarding the fittings, you'd need to find from the maker of the fittings what pressure they're rated to fail at.

    May I ask why you suspect the lineset beneath the slab has failed? Copper pipes in slabs can sometimes fail due to being in contact with iron rebar (electrolysis) but otherwise are typically pretty stout under there. Do you think the possible failure is related to the high pressures the solar assisted system operates under?

    Regarding your energy savings, did I read correctly you replaced a 13 SEER Goodman 2.5 ton unit? And if so, what SEER did you go with as a replacement, and was the tonnage the same?
    • 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.

  2. #67
    Join Date
    Feb 2001
    Location
    N.E. Iowa
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    314
    Quote Originally Posted by Bobberly View Post
    This ^^ doesn't help the thread. I know the manufacturer has been made aware of this discussion and is probably following.
    I sincerely apologize for my outburst.

    I will sit quietly on my hands now and wait for the manufacturer of the product, Sedna Aire Solar Air Conditioner, to explain the theory behind their system and how it can potentially save users 59% on their annual energy costs for cooling.

    I can't find the details of their 10 year warranty on their "web site". Can you please post the wording?
    ______________________________________________

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  3. #68
    Join Date
    Sep 2002
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    13,551

    It's not the copper or the fittings

    Sorry - I didn't think that was the most important question before us now.

    In the sizes used most often in the residential A/C industry the copper tubing has a burst failure point of about 2500 lbs. Mechanical formed joints reduce this to about 2200 lbs. If it has been brazed the burst failure point is reduced to about 1750 lbs.

    The brass flare fittings have a burst failure point of about 5000 lbs.

    Where is the leak site? If I were you I could want each section of the system isolated and separately pressurized, tested, and made leak-free.

    To what do you attribute your saving prior to system failure?

    In what way did the operating environment of the system change between the time of happy cost of operation savings and the time of system failure?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  4. #69
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15
    Quote Originally Posted by Shophound View Post
    Regarding the fittings, you'd need to find from the maker of the fittings what pressure they're rated to fail at.

    May I ask why you suspect the lineset beneath the slab has failed? Copper pipes in slabs can sometimes fail due to being in contact with iron rebar (electrolysis) but otherwise are typically pretty stout under there. Do you think the possible failure is related to the high pressures the solar assisted system operates under?

    Regarding your energy savings, did I read correctly you replaced a 13 SEER Goodman 2.5 ton unit? And if so, what SEER did you go with as a replacement, and was the tonnage the same?
    The system is losing freon somehwere, no traces of oil and the leak detector can't pinpoint. We already eliminated the collector, so that's (Edit: that meaning the lineset) the only logical place left. Pressure may have had something to do with it, I don't know if they had any splices in the line or not.

    The Sedna system was based off a 3.0 ton 16 SEER Westinghouse. They don't sell any half ton units when I purchased mine and 2.0 was determined too small. So increase of half a ton and 3 SEER, decrease of electrical by 15%. With the Goodman setting the thermostat below 78 was futile in the summer. I think the unit was fine but just couldn't keep up on the hottest days.

    I'm actually replacing it with the same model and tonnage that Sedna used (sans thermal collector).
    Last edited by Bobberly; 08-10-2011 at 03:46 PM. Reason: Clarified section

  5. #70
    Join Date
    Feb 2001
    Location
    N.E. Iowa
    Posts
    314
    If the refrigerant lines are in a chase, or "pipe" as you described it, you should be able to detect if there is a leak by holding the detector at the end of the chase while there is pressure in the line-set.
    Or have you tried that already?

    *sitting on hands again*
    ______________________________________________

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  6. #71
    Join Date
    Dec 2009
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    Central Florida
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    15
    Quote Originally Posted by Poodle Head Mikey View Post
    Sorry - I didn't think that was the most important question before us now.
    It wasn't, but I wanted this to explore what could have gone wrong. The failure of a $2 part is what started the whole chain reaction of failures. It could have been abnormal pressure, substandard part, poor installation or any combination of the above.

    Quote Originally Posted by Poodle Head Mikey View Post
    .
    To what do you attribute your saving prior to system failure?
    Unfortunately I was so happy my electric bill dropped I never fully tested my electrical use. I'd say a bulk has to do with Stage 1 cooling using far less power that the previous single stage system I had. I'm sure the collector helped with heat pump use over the winter. I don't have any readings from April up to the first failure to really say what the direct savings from the collector could be.


    Quote Originally Posted by Poodle Head Mikey View Post
    .
    In what way did the operating environment of the system change between the time of happy cost of operation savings and the time of system failure?

    The environment changed when the outside temperature finally reached the hottest it had been since the system was installed. Original install was November, first failure was in June. My hunch was increased heat = increased pressure and we finally hit the point at which the flare fittings gave.

    The fittings were replaced and failed again, which I guess rules out substandard parts; it wasn't until a "gunk" sealent was applied that we were able to stop pressure loss from occuring. About a week later, the compressor cut out while running (don't know the cause) early afternoon. By evening (10pm) I fired it up again and everything was fine until the next day in the afternoon when it cut out again.

  7. #72
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    Dec 2009
    Location
    Central Florida
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    15
    Quote Originally Posted by Fabrk8r View Post
    If the refrigerant lines are in a chase, or "pipe" as you described it, you should be able to detect if there is a leak by holding the detector at the end of the chase while there is pressure in the line-set.
    Or have you tried that already?

    *sitting on hands again*
    Outside they sealed the copper in concrete. Inside the lines are plastered into the drywall under the box supporting the air handler. I didn't want to demo all the drywall just to find concrete there too.

    Will I cross into DIY if I ask how to test the lineset once it's been disconnected? The new lines are going to run through the attic.

  8. #73
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    Aug 2003
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    Fort Worth, TX
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    Quote Originally Posted by Bobberly View Post
    It wasn't, but I wanted this to explore what could have gone wrong. The failure of a $2 part is what started the whole chain reaction of failures. It could have been abnormal pressure, substandard part, poor installation or any combination of the above.
    Was the indoor coil and outdoor coil checked for leaks?


    Unfortunately I was so happy my electric bill dropped I never fully tested my electrical use. I'd say a bulk has to do with Stage 1 cooling using far less power that the previous single stage system I had. I'm sure the collector helped with heat pump use over the winter. I don't have any readings from April up to the first failure to really say what the direct savings from the collector could be.
    I can see the collector, as shown in the disclosed diagrams, helping out a heat pump in heating mode. But not in cooling mode! I do not think it's coincidental that your problems began as the a/c season kicked up a few notches in strength.


    The environment changed when the outside temperature finally reached the hottest it had been since the system was installed. Original install was November, first failure was in June. My hunch was increased heat = increased pressure and we finally hit the point at which the flare fittings gave.
    This is a very important piece of information, right here. The system could have operated just fine in heating mode, but go into cooling mode on a hot day and there's trouble.

    The fittings were replaced and failed again, which I guess rules out substandard parts; it wasn't until a "gunk" sealent was applied that we were able to stop pressure loss from occuring.
    The issue is why the parts failed in the first place. Under normal refrigeration system operating pressures, those fittings should have held. They do fail, but it's typically the flare on the pipe itself, which is much weaker than the nut used to hold the male and female sections of the flare fitting in place. If the flare was made correctly but still failed, then I would suspect system pressures being too high for the flare to hold (not the nut; rather the belled end of the copper tubing).

    About a week later, the compressor cut out while running (don't know the cause) early afternoon.
    Compressors cut out because they get too hot. They are protected by what's called an internal overload protector, which opens the circuit to the motor windings so the motor does not cook itself to death. Two very common things cause compressors to cut out on internal overload: insufficient suction superheat and excess head pressure. As I understand the "solar assist" design here, it can cause both aspects to exist simultaneously.


    By evening (10pm) I fired it up again and everything was fine until the next day in the afternoon when it cut out again.
    Sure, because the solar collector wasn't getting heat from the sun. Makes perfect sense.
    • 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.

  9. #74
    Join Date
    Aug 2001
    Location
    forney texas
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    17,890
    Quote Originally Posted by Bobberly View Post
    Outside they sealed the copper in concrete. Inside the lines are plastered into the drywall under the box supporting the air handler. I didn't want to demo all the drywall just to find concrete there too.

    Will I cross into DIY if I ask how to test the lineset once it's been disconnected? The new lines are going to run through the attic.
    to test the lines by isolating different sections. You havee to find a place where you can cut the lines and cap them off. Then braze some schraders in the line ato pressurize them. put about 300psi in each section and then let them sit for awhile. Then just hook your gauges to each section to see where the leak is.

  10. #75
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361

    Sedna's claims: "How it works." Bogus.

    I did not read the entire thread, The following is my analysis.

    Quote Originally Posted by Bobberly View Post
    .....I've found more information at the following:
    http://www.ecolinegroup.com/index.ph...Technology.htm
    Name:  Sedna solar assisted refrigeration cycle.jpg
Views: 186
Size:  25.7 KB "The Solar Assisted Air Conditioning Cycle"

    "The Sedna Aire System is similar to a regular air conditioning system in that the refrigeration takes place by evaporating liquid with a very low boiling point. In both cases, when a liquid evaporates or boils, it takes some heat away with it, and can continue to do so either until the liquid is all boiled, OK so far. or until everything has become so cold that the sub-zero boiling point has been reached. Nonsense. The difference between the two is how the gas is changed back into a liquid so that it may be used again. A regular air conditioning system uses a compressor to increase the pressure and Temperature on the gas forcing NO. it to become a liquid again through the use of the condenser coil. The change of state of the high temperature, high pressure gas takes place in the condenser though heat exchange. Once the superheat is removed the vapor becomes saturated vapor and the removal of additional heat causes some of the vapor to condense into a liquid. The change of state of the refrigerant, starts to take place approximately 2/3rd's No way. the top 10% of the condenser will remove normal superheat. of the way down the condenser.

    The Sedna Aire Solar Absorption Air Conditioning System uses a different method. It uses the solar heat from the sun to superheat the already superheated refrigerant vapor in the discharge line which enables the refrigerant to begin changing state at the top 2/3rd's of the condenser coil. False. By using this method it reduces the superheat of compression False. required to achieve the cooling process in the conventional cooling systems as well as utilizing more of the condenser cooling face False. of the coil. The conventional air conditioning system is only able to change a portion of the gas into a liquid state False. Subcooling proves that no more saturated vapor exists in the liquid line except in areas of turbulence due to a local pressur drop. so as when the refrigerant enters into the metering device it is a saturated vapor. Absolutelly False. The Sedna Aire process allows more of the refrigerant to change state back into a liquid faster False. as well as allowing the transformation of more liquid into the metering device." False. .


    Look at it this way: If I increase the superheat of the gas entering the condenser (by any means), More of the first portion of the condenser will be required to desuperheat the vapor before it becomes fully saturated and the condensing process begins. That leaves LESS condenser for the process of condensing the vapor. How can a smaller active condenser be more efficient? Smaller active condenser will result in higher pressures, especially during the hottest weather. The discharge pressure that the compressor works against is determined by the condensing temperature of the vapor in the condenser. Raise the condensing temperature (by any means) and the pressures and energy consumption go up.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  11. #76
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
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    1,133
    Quote Originally Posted by Shophound View Post
    I think you're seeing what I'm seeing, here.
    I just play an ignorant redneck hick on TV.
    In my real life, I sleep at a Holiday Inn Express every night.

    Within a closed system, pressure is distributed equally in all directions, which makes the idea pretty much a violation of several Laws of Physics.

    Now, that being said, if they have some type of mechanical pump to move the high pressure, high temp gas into a condenser, then through out the system, they might have something.

    Problem I am having is, unless it is a pump, it won't work. The system has to have a way to move from low to high back to low without equilibrium being reached.

    Hot goes to cold, and high pressure goes to low. Which is a basic reason perpetual motion machines don't work either.

  12. #77
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15
    Umm, how hot does copper need to get to melt insulation?

    This was recovered from the copper leading to the collector:

    http://imageshack.us/photo/my-images...1010007fe.jpg/

  13. #78
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    The top edge of the pipe shows a line of isulation adhering to the pipe. Most likely the insulation was cut and glued. The line is a glue line and the patch well may be from excess glue.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

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