3.2
15907-3
TESTING AND BALANCING HEATING AND VENTILATING SYSTEMS
Apply all instruments in accordance with manufacturer's instructions and
recommendations.
Provide all labor, instruments and appliances required. Do not install instruments
that are permanent installations used for the tests, e.g., gages, thermometers, etc.,
until just prior to the tests to avoid damage and changes in calibration.
Accuracy of all thermometers shall be plus or minus | graduation at the temperatures
to be measured. Graduations shall conform to the following schedule.
Design Temperature Maximum
Medium Differential (°F) Graduation (°F)
Air 10 or less 1/2
Air over 10 l
Water 10 or less 1/10
Water 10-20 1/2
Water over 20 l
AIR SYSTEM PROCEDURES
A.
Adjustments: Adjust all air handling systems to provide the required design air
quantity to, or through, each component. Conduct adjustment and balancing of all
systems during the period of the year approximating maximum seasonal operation,
unless otherwise directed or approved by the Engineer.
Equalizers: Adjust equalizing devices to provide uniform velocity across the inlets
(duct side for supply) of terminals prior to measuring flow rates.
Balance: Use flow adjusting (volume control) devices to balance air quantities only,
i.e., proportion flow between various terminals comprising system, and only to the
extent that their adjustments do not create objectionable air motion or sound, i.e., in
excess of normal limits.
Accomplish balancing between runs (submains, branch mains and branches)
generally by flow regulating devices at, or in, the divided flow fitting.
Restriction imposed by flow regulating devices in or at terminals shall be minimal.
Make final measurements of air quantity after the air terminal has been adjusted to
provide the optimum air patterns of diffusion.
Fan Adjustment: Generally vary the total air system quantities, by adjusting fan
speeds, or axial-flow fan wheel blade pitch. Use damper restriction of a system's
total flow only for systems with direct connected fans (without adjustable pitch
blades), provided system pressure is less than 1/2 inch w.g.
Except as specified herein, make pitot tube traverses of each duct to measure air
flow therein. Pitot tubes, associated instruments, traverses, and techniques shall
conform to the ASHRAE Handbook of Fundamentals.
Omit pitot tubes traverse when the duct serves only a single room of space and its
design volume is less than 200 cfm. In lieu of Pitot tube traverse, determine air flow
in the duct by totaling volume of individual terminals served, measured as specified
herein.
Where duct's design velocity and air quantity are both less than 1000 (fpm/cfm),
determine air quantity by measurements at terminals served.
Test Holes: Provide test holes, in straight ducts, as far as possible downstream from
13089K
