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  • Users: marcoh
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  1. marcoh

    HVAC apps for smart phones?

    I have just upgraded my phone from a Crapberry to a new smartphone, and was wondering what HVAC apps people are using and recommend?
  2. marcoh

    Carrier 23XRV experience

    We are looking at using Carrier 23XRV variable speed screw chillers for a project and the client is concerned about their reliability/expected life. The compressors are a relatively new design, and have been on the marker for 4 years or so. The screw compressor is a tri screw design, which...
  3. marcoh

    pump configurations for variable flow system

    Am looking at a variable flow pumping system, with a total flow rate of 200L/s controlled by VSD's and a pressure sensor in the pipework. Currently the system comprises 1 pump at 200L/s plus a low flow pump of 60L/s (plus a standby 200L/s pump). Normally the system runs with the single 200L/s...
  4. marcoh

    Seconday chilled water pumping options

    Am looking at a variable flow secondary chilled water pumping system, with a total flow rate of 200L/s controlled by a pressure sensor in the pipework. Currently the system comprises 1 pump at 200L/s plus a low load pump of 60L/s (plus a standby 200L/s pump). Normally the system runs with the...
  5. marcoh

    Displacement AC humidy control

    Am trying to find some design guidelines on designing for space RH control using displacement ventilation systems. The design parameters are 23ºC / 50% or 8.86g/kg moisture in the occupied zone. For a mixing system the the design is straightforward and the dehumidified supply air needs to...
  6. marcoh

    Using treated effluent for Cooling Tower makeup

    A client has asked advice on using treated effluent from a municipal wastewater treatment plant as makeup water for the cooling towers. Economically it makes a lot of sense as the water is much cheaper (WWTP is next door). What effects will this have on the cooling tower water treatment...
  7. marcoh

    Kt factors for larger diameter pipes

    I am looking at the pressure loss for a 500mm diameters pipe system and the loss coefficient chart indicated that the pressure drop for a 45 degree bend is greater than a 90 degree bend? The table give Kt values as follows: 90 deg , 45 deg 100mm: 0.21 , 0.18 150mm: 0.17 , 0.17...
  8. marcoh

    low temperature VAV systems

    I am looking at an office air conditioning system utilising low temperature VAV systems. The client is not interested in chilled beams, displacement AC, but does want the system to be as energy efficient as possible. Pros include significantly lower air quantities, ducts, risers, energy...
  9. marcoh

    pipethrust allowance?

    Simple question probably but I have little experience in designing piping systems. I have a 500mm pipe attached to the side of a building on brackets. The pipe run is fairly simple and essentially a 'Z' shape with 2 right angle bends. The pipe is to be pressure tested to 1000kPa and maximum...
  10. marcoh

    magnetic bearing chillers

    We are looking at installing some McQuay WMC water cooled frictionless magnetic bearing centrifugal compressor chillers. Main reason for selecting these chillers is their part load energy efficiency and the capacities they come in suits the building well. I have heard (rumours from...
  11. marcoh

    Non chemical water treatment systems

    What are peoples experiences with non chemical water treatment systems for cooling towers in lieu of traditional chemical based systems? Listening to the sales pitches these system are perfect, listening to feedback from competitors and maintenance people, everything is not always as rosy as...

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