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CLCH-SVX013B-EN
71
When a single transmitter is supplied in a multiple fan
system, one or more fans will be brought back to the
transmitter as a manifold and the airflow will represent the
total airflow for the system. As a result, the factor should
be adjusted as follows:
K = N * K-Factor from
Where:
K = The final factor to be used for controller
programming.
N = The number of active
*
fans in the system.
*
If a fan fails in a multiple fan system where only one
transmitter is being supplied, and if the remaining fans will
continue to be used, the factor should be reduced
accordingly. Additionally, if the inactive fan was included
in the manifold back to the transmitter, the tubes from the
inactive fan should be temporarily removed and replaced
with tubes from an active fan (or simply plugged).
When a transmitter is supplied for each fan, the factor does
not need to be adjusted. The resulting airflow will
represent single-fan airflow. At the controller level, the
individual airflows should be summed to get the total
airflow. If a field-provided K-factor is to be used (see
below), the measured airflow for the system should be
divided by the number of active fans to get a single-fan
K-factor.
Field-obtained factors can provide maximum accuracy. To
obtain the factor in the field, measure the differential
pressure output from the transmitter while measuring the
airflow through the system. Once these two values have
been measured, simply solve for K using the following
equation:
K = ACFM/SQRT(DP)
Where:
K = Field-provided constant factor.
ACFM = Actual airflow (ft
3
/min.) being measured at the air density
being measured.
DP = Differential pressure (inches w.g.) being measured by the
transmitter.
External Insulating Requirements
The following areas should be specifically addressed, as
applicable:
•
Supply and return water piping connections
•
Supply and return refrigerant piping connections
•
Condensate drain lines and connections
•
Outdoor-air-intake duct connections
•
Discharge duct connections
•
Special requirements for low-temperature-air systems
Summary of Contents for Performance Climate Changer PSCA
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