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Copyright 2019 - NICHOLAS A. CHAZAPIS

1. Pre-Commissioning

In order to minimize the on-site commissioning time and help eliminate the adverse effects of reduced commissioning timescales, as  much pre-commissioning process as possible should  be performed off-site. 

Off-site pre-commissioning tasks include: 

  • Control Application software. Check DDC routines with realistic default values. A witness some or all of these checks at this time is possible. 
  • A record of all settings, set points and offsets. Check specified set points have been configured. Interlocks and Control loops 
  • Sequence of operations as specified. 
  • Start-up and shutdown procedures.
  • Plant changeover.
  • Alarm functions.
  • User interface software.
  • Control panels, Factory aceptance tested.
  • Integration gateways (partial).

off site


 

AIR HANDLING UNITS “LOGIC STRATEGIES”

Logic Strategies: The BAS will fully control the air handlers. Generally the BAS will energize the AHU (start the fans and activate control loops) as dictated for each air handler. The detailed “logic strategies” will be required by reference to them in each of the individual sequences specified elsewhere.

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AIR HANDLING UNIT “DIAGNOSTICS STRATEGIES”

  1. Diagnostic Strategies: In addition to the standard alarm limits specified for all sensed variables the BAS monitor and diagnose anomalies in the operation of the air handlers.
  2. The following “diagnostic strategies” will be included by reference with each air handler with any specific clarifications required:
    1. Run Time Limit: BAS will accumulate the runtime of the status of associated rotating equipment and enunciate a level 5 alarm to indicate that the unit is in need of service.
    2. Filter Monitoring: BAS will monitor the differential pressure transmitter across the filter bank(s). A level 5 alarm will be reported when pressure drop exceeds the transmitter’s setting.
    3. Start Monitoring: BAS will accumulate the starts of cycling equipment. BAS will further enunciate a level 5 alarm when the number of starts exceeds the specified value within the specified time period. (ie: more than 3 starts in a 30 min period).

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AIR HANDLER “MONITORING AND MANAGEMENT”

 

General: The BAS will monitor various aspects of the air handling systems and calculate parameters as specified below to facilitate operations and management.

Trending: The BAS will continuously monitor, calculate and display the following parameters at the intervals indicated. These values will be stored initially in the buffer of the controlling control unit, and then be uploaded periodically and stored on a specified hard disc.

Parameters to be trended:

a) All temperature sensors at 1 hour intervals

b) All relative humidity sensors at 1 hour intervals

c) All pressure sensors at 1 hour intervals

d) All run requests and statuses on a change in value

e) All analog loop outputs on 1 hour intervals

f) Calculated enthalpies in 2 hour intervals

g) Summed cooling and heating requests on 2 hour intervals

 2. CX stamp