Wash. Admin. Code § 51-11C-40355 - Section C403.5.5-Economizer fault detection and diagnostics
C403.5.5
Economizer fault detection and diagnostics (FDD). Air-cooled
unitary direct-expansion units with a cooling capacity of 54,000 Btu/h or
greater listed in the tables in Section C403.3.2 that are equipped with an
economizer in accordance with Section C403.5 shall include a fault detection
and diagnostics (FDD) system complying with the following:
1. The following temperature sensors shall be
permanently installed to monitor system operation:
1.1. Outside air.
1.2. Supply air.
1.3. Return air.
2. Temperature sensors shall have an accuracy
of +-2°F (1.1°C) over the range of 40°F to 80°F (4°C to
26.7°C).
3. Refrigerant
pressure sensors, where used, shall have an accuracy of +-3 percent of full
scale.
4. The unit controller shall
be configured to provide system status by indicating the following:
4.1. Free cooling available.
4.2. Economizer enabled.
4.3. Compressor enabled.
4.4. Heating enabled.
4.5. Mixed air low limit cycle
active.
4.6. The current value of
each sensor.
5. The unit
controller shall be capable of manually initiating each operating mode so that
the operation of compressors, economizers, fans and the heating system can be
independently tested and verified.
6. The unit shall be configured to report
faults to a fault management application available for access by day-to-day
operating or service personnel or annunciated locally on zone
thermostats.
7. The FDD system
shall be configured to detect the following faults:
7.1. Air temperature sensor
failure/fault.
7.2. Not economizing
when the unit should be economizing.
7.3. Economizing when the unit should not be
economizing.
7.4. Damper not
modulating.
7.5. Excess outdoor
air.
Notes
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