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Recent content by tbedford

  1. tbedford

    Pressure relief valve inlet sizing

    Photo of installed PRV Thank you, Tomhttps://files.engineering.com/getfile.aspx?folder=23a581a6-91ee-4cd4-892e-63c95b5737a4&file=image001.png
  2. tbedford

    Pressure relief valve inlet sizing

    I am commissioning a dual fuel natural gas/oil hydronic boiler by Bryan Boilers. Input MBH is 1200/600 and output is 1002 MBH. Boiler MAWP is 160 psig. I have attached a photo of PRV installed on top of boiler. Intuitively, a reduction in size from 2" to 3/4" orifice represents a significant...
  3. tbedford

    Btu meter location

    Good morning, If I am interested in overall energy consumption from the heating boilers in a building, is it more advantageous to locate the energy meter in the hot water supply line or the hot water return line? Simple question but maybe not a simple answer! Tom
  4. tbedford

    4 stages cooling with only 2 piping circuits

    Good morning, I hope everyone is staying safe during Covid precautions. To provide some background, my installation is in a school in Edmonton, Alberta, Canada. A Daikin RCS045D condensing unit with 4 compressors provides cooling and hot gas bypass if required. The condensing unit is internally...
  5. tbedford

    Dry-Type Dstribution Transformers

    Thank you for the quick response. t
  6. tbedford

    Dry-Type Dstribution Transformers

    Hello, I have recently completed startup on several large air handlers. Each air handler has a service corridor maintaining room temperature. There are four transformers in each corridor and they all have surface temperatures of 150F. I expect high temperatures on transformers, but is this too...
  7. tbedford

    Calibrating VAV boxes

    Thank you ChasBean1, Except for basement and some areas on first floor, the velocities were generally above 500 fpm. Having said that, there were times when we just packed up because control and Cx were playing with the systems and our air flow dropped off to zero or near zero. While the theory...
  8. tbedford

    Calibrating VAV boxes

    Thanks again Lnewqban, Do the VAV boxes require 2 reference airflow measurements at calibration or is one airflow low reference sufficient? Thx,
  9. tbedford

    Calibrating VAV boxes

    Thank you Lnewqban for your input, We completed the VAV box calibration work in stages, by floor about 3 months ago. The air supply was spotty and very often we did not have enough air to meet the maximum flow even though there may have been 125 Pascals(1/2 iwc) or more at each box. Now when we...
  10. tbedford

    Calibrating VAV boxes

    We have tried to shorten the construction time of a 6 storey hospital building. There are 1626 supply, return and exhaust boxes controlled by a Honeywell ComfortPoint system. In the majority of areas, there are 1 or 2 ceiling diffusers for each VAV box. During construction, we blanked off duct...
  11. tbedford

    5 Chillers and Pressure relief

    Thanks dbill74, The refrigerant sitting in the pipe after a release is what got me questioning the design and configuration.
  12. tbedford

    5 Chillers and Pressure relief

    thanks BI
  13. tbedford

    5 Chillers and Pressure relief

    Thank you LittleInch, The refrigerant will evaporate immediately at approx. -14F(-26) and then it is all gas flow after that. It won't even accumulate for more than a couple of minutes. It also begs the question should the pipe be insulated; although an un-insulated pipe with condensation in...
  14. tbedford

    5 Chillers and Pressure relief

    LittleInch, B52 is the Canadian refrigeration Installation Code. I have also read ASHRAE 15 and 34 which cover mechanical room design. Each chiller contains 525 pounds of R134a, class A1 refrigerant. Evaporator has a 1" relief valve with a 200 psig rating at a flow of 48 lbs./min. The...
  15. tbedford

    5 Chillers and Pressure relief

    This is a new problem for me. I am commissioning a hospital with 5 Trane series RTHD chillers. Unfortunately, the machine room is located in the basement and in the center of the building footprint. The chiller pressure relief valves (3 per chiller) are piped and sized correctly into a common...
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