Loading ...
Sorry, an error occurred while loading the content.

Evaporative cooling for roof and outside AC unit

Expand Messages
  • Todd
    Last summer some HREG members mentioned significant savings by installing a roof watering system. I m wanting to rig up one in preparation for this summer s
    Message 1 of 4 , Apr 15, 2006
    • 0 Attachment
      Last summer some HREG members mentioned significant savings by
      installing a roof watering system. I'm wanting to rig up one in
      preparation for this summer's blistering heat.

      I live in an old building in downtown Monroe, LA, with a flat roof
      over my shop. This part of the roof has no insulation. It is 30' x
      50' My plan is to have a thermostat, timer and solenoid to allow an
      alternating water/evaporation routine.

      Basically, 10 seconds water spray, 10 minutes off for evaporation.

      Some have mentioned using a 555 electronic timer, available at Radio
      Shack. Well, they don't carry those anymore. What do y'all suggest
      for the timer? Please give specific part numbers or resources.
      This is not my strong area.

      Beyond a timer, I'm thinking of a in-line valve like they use in
      irrigation such as a Toro 3/4" 24AC valve from Home Depot. Part
      number: 53380, store SKU 167555, price $13.97.

      Home Depot also has a valve from Orbit (model 57223, SKU 794864,
      $10.99) that is referred to as a "3/4" FIP Electric Anti-Siphon
      Inline Valve with Flow Control." I'm assuming this is still a
      solenoid valve that also has anti-siphoning. Right?

      A buddy used a timer designed for attic fans. He got the
      model#2E340 attic fan thermostat from Grainger's at $21.75.

      I still need some sort of timer to control the 10 sec on/ 10 min.
      off.

      Any ideas?

      Todd T
    • Todd
      Ooops. I forgot to mention the AC unit mist cooling idea. My building has two AC units: one for the office area downstairs and one for my loft apartment
      Message 2 of 4 , Apr 15, 2006
      • 0 Attachment
        Ooops. I forgot to mention the AC unit mist cooling idea.

        My building has two AC units: one for the office area downstairs and
        one for my loft apartment upstairs. My loft already has enough
        ceiling and roof insulation to rule out using the evaporative
        cooling idea on the flat roof surface, but the AC unit is up there.

        Last year I installed a shade screen on the South and West sides,
        open on the bottom 18" for air intake and open on the top for
        exhaust.

        This year I want to add a water mist to cool off the outside unit.
        I've heard folks talk about a solenoid triggered off the 24v signal
        from the thermostat to the outside fan unit. Basically, when the
        outside unit is running, the water is spraying.

        The idea is to cool the outside unit by evaporation, thus lowering
        the head pressure and supposedly lowering the AC air temp inside.

        Does the Central AC have enough 24v signal strength to add a
        solenoid valve to it... to control the water flow?

        What size mist heads? Do I need to go as low as a .5gph or .75gph
        like the mist cooling systems use?

        I plan to add a 200 line filter and have seen the phosphate
        cartridges to prevent scale buildup on the AC unit. Suggestions?

        By the way, I applied white mobile home roof coating years ago and
        it made a tremendous difference.

        Todd
      • Paul Archer
        555 timers can be found at prety much any electronics supply house, for example, Mouser Electronics (www.mouser.com) for less than the cost of shipping.
        Message 3 of 4 , Apr 16, 2006
        • 0 Attachment
          555 timers can be found at prety much any electronics supply house, for
          example, Mouser Electronics (www.mouser.com) for less than the cost of
          shipping. However, I'd suggest going the X10 route. For about $30 or so, you
          can get from X10.com either an appliance module or a "universal" module
          (depending on your setup) to actually turn your valve on and off, and an
          "Activehome" computer interface. you can set the interface up however you
          like, and even remove it from the computer.
          It's not quite a turnkey solution, but it's pretty close.

          Paul Archer


          Yesterday, Todd wrote:

          > Last summer some HREG members mentioned significant savings by
          > installing a roof watering system. I'm wanting to rig up one in
          > preparation for this summer's blistering heat.
          >
          > I live in an old building in downtown Monroe, LA, with a flat roof
          > over my shop. This part of the roof has no insulation. It is 30' x
          > 50' My plan is to have a thermostat, timer and solenoid to allow an
          > alternating water/evaporation routine.
          >
          > Basically, 10 seconds water spray, 10 minutes off for evaporation.
          >
          > Some have mentioned using a 555 electronic timer, available at Radio
          > Shack. Well, they don't carry those anymore. What do y'all suggest
          > for the timer? Please give specific part numbers or resources.
          > This is not my strong area.
          >
          > Beyond a timer, I'm thinking of a in-line valve like they use in
          > irrigation such as a Toro 3/4" 24AC valve from Home Depot. Part
          > number: 53380, store SKU 167555, price $13.97.
          >
          > Home Depot also has a valve from Orbit (model 57223, SKU 794864,
          > $10.99) that is referred to as a "3/4" FIP Electric Anti-Siphon
          > Inline Valve with Flow Control." I'm assuming this is still a
          > solenoid valve that also has anti-siphoning. Right?
          >
          > A buddy used a timer designed for attic fans. He got the
          > model#2E340 attic fan thermostat from Grainger's at $21.75.
          >
          > I still need some sort of timer to control the 10 sec on/ 10 min.
          > off.
          >
          > Any ideas?
          >
          > Todd T
          >
          >
          >
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
          >
          >



          -----------------------------------------------------------
          If you live in a small town /You might meet a dozen or two/
          Young alien types /Who step out /And dare to declare/
          "We're through being cool." -- Devo, "Through Being Cool"
          -----------------------------------------------------------
        • larry
          Most of the new high SEER rated AC units have larger condensing coils, and smaller compressors, and matching with a large inside coil. We have have added a
          Message 4 of 4 , Apr 16, 2006
          • 0 Attachment
            Most of the new high SEER rated AC units have larger condensing coils, and
            smaller compressors, and matching with a large inside coil.

            We have have added a secondary condensing coil to our units, with solar
            operated fan. The secondary coil was from an old 3 ton unit (obtained for
            free). The compressor and fan were removed, and then connected in line with
            exiting condensing coil. The head pressure was reduced significantly and
            AMP usage dropped 2-3 amps. Other things we did were run the high and low
            side lines together and insulated heavily from condensing unit to
            evaporator. The low side (cold will help cool down high side line. Recommend
            insulating both lines, attics are hot and will effect high side line. We
            are also adding a water cooling unit (simple heat exchanger) which obtains
            water from the drain pan in attic, the water is already chilled and cools
            down high side. After running through exchanger, water is diverted to
            landscape watering.

            larry



            On 4/15/06 4:39 PM, "Todd" <toddt58@...> wrote:

            > Ooops. I forgot to mention the AC unit mist cooling idea.
            >
            > My building has two AC units: one for the office area downstairs and
            > one for my loft apartment upstairs. My loft already has enough
            > ceiling and roof insulation to rule out using the evaporative
            > cooling idea on the flat roof surface, but the AC unit is up there.
            >
            > Last year I installed a shade screen on the South and West sides,
            > open on the bottom 18" for air intake and open on the top for
            > exhaust.
            >
            > This year I want to add a water mist to cool off the outside unit.
            > I've heard folks talk about a solenoid triggered off the 24v signal
            > from the thermostat to the outside fan unit. Basically, when the
            > outside unit is running, the water is spraying.
            >
            > The idea is to cool the outside unit by evaporation, thus lowering
            > the head pressure and supposedly lowering the AC air temp inside.
            >
            > Does the Central AC have enough 24v signal strength to add a
            > solenoid valve to it... to control the water flow?
            >
            > What size mist heads? Do I need to go as low as a .5gph or .75gph
            > like the mist cooling systems use?
            >
            > I plan to add a 200 line filter and have seen the phosphate
            > cartridges to prevent scale buildup on the AC unit. Suggestions?
            >
            > By the way, I applied white mobile home roof coating years ago and
            > it made a tremendous difference.
            >
            > Todd
            >
            >
            >
            >
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
            >

            Naturallighting.com
            1939 Richvale
            Houston, Texas 77062

            Toll Free 1.888.900.6830
            FAX 281.488.0823

            email: larry@...
            http://www.naturallighting.com
          Your message has been successfully submitted and would be delivered to recipients shortly.