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Recent content by SAK9

  1. SAK9

    REQUIREMENT OF COOLING TOWER IN WATER COOLED CHILLER SYSTEM

    The process equipment with in a chemical plant are more tolerant to temperature changes outside of the design limits though heat transfer efficiencies might suffer. You need to be mindful of the fact HVAC chillers are lot more sensitive to cooling water temperature ranges as well as the...
  2. SAK9

    Chilled Water Constant Flow Reverse-Return Bypass

    If all chillers are going to be operating all the time a bypass valve is not required. You can select a pump for the flow anticipated for future chillers as well and run it at reduced speed for current flow. Please make sure that the pump selection will meet flow and head requirements under both...
  3. SAK9

    HVAC for Nitric Passivation Line

    I am not sure how partitioning up the passivation area will help if you have a common AHU serving both spaces and if it is based on air recirculation. Contamination will spread through to the whole space through the air distribution system in no time. Secondly air change range recommended for...
  4. SAK9

    Chilled Water Constant Flow Reverse-Return Bypass

    Cooling tower systems are generally designed as constant flow systems as tower characteristics change drastically when the flow drops below a certain limit. As you have a large number of chillers/heat exchangers receiving water from the system it is quite possible that some of the chillers may...
  5. SAK9

    White Rust in HVAC Ductwork, again

    Get the ducts replaced that is the only lasting solution. Moreover it is a healthcare facility and an air quality check may expose you to potential insurance claims. If the duct work is not very old you need to investigate what is causing this for eg saline air in a coastal area. If weather is...
  6. SAK9

    Water Chiller selection

    You need to create an annual load profile for the facility with the percentage of operational time at each segment of the load profile. Once you complete the load profile you may see that the the building peak load occurs for less than 10% of total operation time. You need to find out from the...
  7. SAK9

    Return fan of a large AHU

    Please check the design to see if there are any exhaust dampers on the system. I have seen hospitals being designed with a purge system that allows the air handling system to function on a 100% fresh air mode. Usually the purge cycle is done in the morning when the temperature is favourable and...
  8. SAK9

    Inquiry Regarding Career Opportunities in HVAC Design

    I would suggest a course in Revit MEP and look for opportunities to work as a Revit MEP designer with either consulting or contacting industries. As you gain more experience as a designer you can move up to an engineer role. You can utilise your operational and maintenance experience to create...
  9. SAK9

    on/off chiller unit for a batch production

    A buffer tank or a balancing tank with hot/cold well is very common in all production facilities requiring process cooling. The chiller capacity and production demand is never going to match so you need a buffer to stop the chiller from cycling on/off.If the production load is of short duration...
  10. SAK9

    HVAC System with VRV or Chiller System is Cheaper ?

    VRV system will be obviously cheaper. You can save more by using ductless systems. There is also cost saving as the VRV system comes with its own control system so you may not require a full on building automation system required for chilled water systems
  11. SAK9

    Heat pump ?? in DHW production

    There is a limitation on the number of times the heat pump compressor can start in an hour usually not more than 6-7 times in an hour. Therefore you need a buffer storage tank that will smoothen the fluctuating field flow requirement. This buffer tank sizing will also take into account seasonal...
  12. SAK9

    Redesign for Latent Load

    You can solve the problem by supplying ventilation air at a neutral temperature say 21C.The ventilation AHU needs to cool down to at least 13C( or lower as allowed by the chilled water flow temp) to wring out all moisture from the air and then reheat it to 21C.This is how it is done in hotels...
  13. SAK9

    Evaluation of HVAC System Configurations for Multi-Tower High-Rise Project with VPF chiller system

    VPF is not a panacea for all new buildings. Its use is limited to simple designs. A more complex campus like building layout still requires the conventional primary-secondary system. Functionality is more important than minor improvement in energy efficiency.
  14. SAK9

    Addressing Disparities in Flow Rates for Efficient HVAC System while considering diversity

    Thanks for asking a good question Smali1! This is how you do it: Before you start the balancing process you isolate a certain number of AHUs/FCUs equivalent to 250 tons in your case. You start the pump and balance the operational units at their maximum design flows. Once you accomplish the...
  15. SAK9

    PRESSURE INDEPENDENT VAV - ISSUES

    If I understood you correctly some of the VAV boxes have air flowing in reverse direction when the AHU is shut off. This means the space is at a higher pressure/temperature than the duct and air is flowing out of the space through a path of least resistance. The exfiltration could be due to...
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