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  1. #14
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    Jun 2009
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    Toronto
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    7

    Red face

    Quote Originally Posted by bmathews View Post
    Heat transfer using water is the most efficient way, then air to air then static. HVAC 101. If you could recapture the water then cool it down and re-use it, it would work fine. Look at using tower systems on water source heat pumps. The problem is that the energy you use to cool the water down through a series of pumps and fans would use more energy than just buying a high efficient a/c unit. It is only economically feasible on large projects, not for 1 unit on a house. You also need to treat the water being sprayed on your condenser coils which adds an entire other expense. There is a guy locally that makes his own condensing units, using water as the medium. They are quite pricey from what I understand, require regular maintenance as well as water treatment. They basically use a pool pump to spray the water over the coils. Which uses whatever amount of electricity. They are very pretty and make people feel good about themselves.
    Very interesting!!!!!

  2. #15
    Join Date
    Jul 2009
    Location
    Fort Worth, Texas
    Posts
    138
    The Cool-n-Save seems like trouble! Let’s say we have a 2 or 2.5 ton system. On a mild day 80-85 outside ambient. Your head pressure would be so low that your suction pressure would fall below freezing. Now you have liquid coming back to the compressor. It just seems like a sure fire way to kill your compressor. Remember if it’s a fixed metering device when the head pressure falls the suctions falls with it. I.E. head pressure controls.

  3. #16
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    Jul 2009
    Posts
    26
    pretty pessimistic replies I think for a rather solid physics law proven to work. lowering head pressures means it DOES work and an system could be optimized to utilize water. What I think is friggin funny is I was introduced to this about 15 years ago!!! I am confident if I look up their patent, it would only be on the little valving device and not the concept of using water.

    The reason it works is the physics laws of latent heat of vaporization of water which is nearly 1000 BTU/lb. LHV is key for refrigeration systems in getting out MORE than you put IN so to speak. Electrically anyway. You can get the same effect as the patented product by introducing streams of water to the coils as well. Either way, when the water changes state, it requires energy to do it and that energy is heat.

    I am sure many main stream pros will say it is junk, but as an engineer, I say give it time and some people will be eating their words because just because a coil may corrode with this does not keep new technology from advancing to create a composite or otherwise hybrid coil system that is impervious to these problems.

    Small take would be to combine the thermal conduction properties of copper with the anti-corrosion properties of stainless..... I would embrace this stuff with open arms but..........

    Regarding head pressure issues, quite obviously that could be corrected in design stages. I can certainly see it as a problem for the average home owner but not for a "PRO".

  4. #17
    Join Date
    Apr 2007
    Posts
    6,285
    Quote Originally Posted by viper1 View Post
    pretty pessimistic replies I think for a rather solid physics law proven to work. lowering head pressures means it DOES work and an system could be optimized to utilize water. What I think is friggin funny is I was introduced to this about 15 years ago!!! I am confident if I look up their patent, it would only be on the little valving device and not the concept of using water.

    The reason it works is the physics laws of latent heat of vaporization of water which is nearly 1000 BTU/lb. LHV is key for refrigeration systems in getting out MORE than you put IN so to speak. Electrically anyway. You can get the same effect as the patented product by introducing streams of water to the coils as well. Either way, when the water changes state, it requires energy to do it and that energy is heat.

    I am sure many main stream pros will say it is junk, but as an engineer, I say give it time and some people will be eating their words because just because a coil may corrode with this does not keep new technology from advancing to create a composite or otherwise hybrid coil system that is impervious to these problems.

    Small take would be to combine the thermal conduction properties of copper with the anti-corrosion properties of stainless..... I would embrace this stuff with open arms but..........

    Regarding head pressure issues, quite obviously that could be corrected in design stages. I can certainly see it as a problem for the average home owner but not for a "PRO".
    As an engineer then you would know that filtering all of the minerals out of the water would leave the water at a point of negative CSI. You know what acidic water does to metal. No way around that without treating the water to a point near 0.0 on the CSI before it's sprayed onto the condenser.

    CSI = Calcium Saturation Index

    As far as creating a coil impervious to this condition: Don't forget the efficiency standards are not going down but up. Anything you put in between n efficient material to transfer heat will influence that. Does that mean they can't put some coating on a 19 SEER system to achieve that? No. But then why would they be designing air cooled systems in the first place. Seems counter productive. They are made as air cooled units not water cooled. If they wanted water cooled they've been around a while I'm sure they could think of something better than a mister.

  5. #18
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    Aug 2003
    Location
    Fort Worth, TX
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    11,086
    Quote Originally Posted by viper1 View Post
    pretty pessimistic replies I think for a rather solid physics law proven to work. lowering head pressures means it DOES work and an system could be optimized to utilize water. What I think is friggin funny is I was introduced to this about 15 years ago!!! I am confident if I look up their patent, it would only be on the little valving device and not the concept of using water.

    The reason it works is the physics laws of latent heat of vaporization of water which is nearly 1000 BTU/lb. LHV is key for refrigeration systems in getting out MORE than you put IN so to speak. Electrically anyway. You can get the same effect as the patented product by introducing streams of water to the coils as well. Either way, when the water changes state, it requires energy to do it and that energy is heat.

    I am sure many main stream pros will say it is junk, but as an engineer, I say give it time and some people will be eating their words because just because a coil may corrode with this does not keep new technology from advancing to create a composite or otherwise hybrid coil system that is impervious to these problems.

    Small take would be to combine the thermal conduction properties of copper with the anti-corrosion properties of stainless..... I would embrace this stuff with open arms but..........

    Regarding head pressure issues, quite obviously that could be corrected in design stages. I can certainly see it as a problem for the average home owner but not for a "PRO".
    How about a better idea. Let's reduce the heat gain to the building, not goof around with sprinkler mist heads on condensing coils. Reduce the heat load, reduce the amount of heat the condenser must reject to the outdoors, reduce the power draw. Concurrently, no water wasted when a more long term approach is on the job 24/7/365 making building occupants comfortable and not draining their wallet day to day, month to month, year to year.

    Sure, I'll grant the engineering and thermodynamics of turning a residential condenser into an evaporative condenser sounds exciting, but it's more satisfying to address the problem of excessive heat gain to a structure directly vs. essentially pissing on it with a sprinkler head.
    • 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. #19
    Join Date
    Jul 2007
    Posts
    45
    I hear you on the reducing the load. I think a better vented roof with heat reflective shingles is the best way to do that for my house at this point.

    Cool-n-save does look like an interesting idea. I'm sure you could get around their patent by hooking up a 24v sprinkler valve instead of their paddle for controlling the water flow. (also solves the heat pump problem with this product if you look at the reversing valve control.) That along with some kind of temperature control you could solve the freezing refrigerant, only use the mist on the hottest days when all the water will be sure to evaporate anyway and not have a chance to generate mold, etc.

    I don't plan to try any of this, it just sounded interesting to me.

    I'm sure if it was really effective the manufacturers would be building swamp cooler like condenser units, where they actually build the heat transfer material to take water and have a small fish tank pump that re-circulates the water over the "non corrosive material based" fins and takes in extra water as the reservoir level goes down. If you've ever seen a swamp cooler, it's a pretty simple system that does lower the temperature quite a bite in low humidity.

    If they need to get past 20+ SEER maybe they might start implementing techniques like this for climates that are not humid.




    Quote Originally Posted by shophound View Post
    How about a better idea. Let's reduce the heat gain to the building, not goof around with sprinkler mist heads on condensing coils. Reduce the heat load, reduce the amount of heat the condenser must reject to the outdoors, reduce the power draw. Concurrently, no water wasted when a more long term approach is on the job 24/7/365 making building occupants comfortable and not draining their wallet day to day, month to month, year to year.

    Sure, I'll grant the engineering and thermodynamics of turning a residential condenser into an evaporative condenser sounds exciting, but it's more satisfying to address the problem of excessive heat gain to a structure directly vs. essentially pissing on it with a sprinkler head.

  7. #20
    Join Date
    Jun 2001
    Location
    DFW
    Posts
    683
    Fujitsu has some new minisplits with SEER ratings up to 26. All done with air.

    Once upon a time, there was a company that built a water cooled condenser unit for the home. It pumped the water over swamp cooler pads that surrounded the condenser. The fan pulled air through the pads cooling the water, which ran down into the bottom of the unit. The condensing coil sat in the bottom of the condenser and was immersed in the cool water. It used condensate from the evaporator coil in combination with tap water to make up for evaporation. It just never caught on.

  8. #21
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    Apr 2007
    Posts
    6,285

  9. #22
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    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,086
    Quote Originally Posted by paul42 View Post
    Fujitsu has some new minisplits with SEER ratings up to 26. All done with air.

    Once upon a time, there was a company that built a water cooled condenser unit for the home. It pumped the water over swamp cooler pads that surrounded the condenser. The fan pulled air through the pads cooling the water, which ran down into the bottom of the unit. The condensing coil sat in the bottom of the condenser and was immersed in the cool water. It used condensate from the evaporator coil in combination with tap water to make up for evaporation. It just never caught on.
    It never caught on because homeowners and water cooled condensing strategies don't mix very well. Years ago a seasoned HVAC tech, mentoring me in the trade, had a discussion on this topic. He knew I was familiar with the old redwood natural draft cooling towers I'd seen in some residential backyards in the 60's. He told me that when the systems were well maintained they worked great, outperforming the air cooled equivalent tonnage of the day by a long shot. But...most of the ones he had serviced were not maintained well. It's difficult enough for homeowners to remember their air cooled condensing unit needs a good cleaning at least once per year. Add water to the mix and it's double the trouble.
    • 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.

  10. #23
    Join Date
    Jul 2008
    Location
    Washington, DC
    Posts
    1,569
    window units and small hotel through the wall units often have slingers that throw the condensate on the condenser coil. It reduces the head pressure and saves energy. The water is distiiled water and has no minerals.

    Minerals in tap water will coat the aluminum finned coil and create an insualting barrier and then eventually clog the spaces between the fins. The chemicals that are strong enough to remove the minerals, such as those used to clean the copper tubes in water cooled macdhines, are too corrosive for the aluminum. So after a while you just have a scaled condenser with no way to clean it.
    Steamfitters Local 602

  11. #24
    Join Date
    Jun 2009
    Location
    Central Texas
    Posts
    47

    recycling the condensate

    how about this. reroute the condensate drain to drip over the liquid line where it comes out of the coils and from there let it overflow to drip on the hot gas line out of the compressor. the energy that was used to condense the moisture in the house would then be used to increase the efficiency of the condensing coil.

    when the operating design temp of the condensing unit is exceeded by 10° or more like it has been lately in some parts of the country, temporarily spraying a little water on the coils sure sounds tempting. An icemaker or washing machine valve could easily be rigged up off the contactor and a water supply turned on when it's really hot outside. Could also get creative by using a temp sensor or psi switch.

  12. #25
    Join Date
    Feb 2007
    Posts
    190
    Nothing in this world is free. In order for this to be as remarkable as described there would have to be some conspiricy between all of the major manufacturers. Carrier, Trane, Lennos et al are trying to squeeze everybit of efficiency out of this equipment. If they could use this technology they would be all over it!

    In the 78's or 80's there was a product called the "Mist Mizer" sprayed based on Head pressure. The coil woud be corroded in 6 months

  13. #26
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    Jul 2008
    Location
    Washington, DC
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    Quote Originally Posted by glockdoc View Post
    how about this. reroute the condensate drain to drip over the liquid line where it comes out of the coils and from there let it overflow to drip on the hot gas line out of the compressor. the energy that was used to condense the moisture in the house would then be used to increase the efficiency of the condensing coil.

    when the operating design temp of the condensing unit is exceeded by 10° or more like it has been lately in some parts of the country, temporarily spraying a little water on the coils sure sounds tempting. An icemaker or washing machine valve could easily be rigged up off the contactor and a water supply turned on when it's really hot outside. Could also get creative by using a temp sensor or psi switch.
    Actually on some commercial refrigeration units they have the condensate drain into a stainless pan and there is a coil of liquid line laying in the bottom of the pan. So what you suggest has been done. You need plenty of surface area, not just a drip on the liquid line.

    As far as your other suggestion, besides the corrosion that has been mentioned, at some point the cost of water comes in. Ever have a toilet flapper go bad and not get to it for a while? You can get a heck of a water bill real quick.

    The other thing is this. Years ago they had systems were city water went into a once through water cooled condenser, straight in and then down the drain. Most all jurisdictions have adopted codes preventing this, I would not be surprised if any sort of condenser spray system was in violation of this part of the code.
    Steamfitters Local 602

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