Carrier 42C,V Manual de instalación descargar pdf (Pagina 79)

Variable Airflow for 0-10 Vdc Input (42SM Only) (See

Fig. 97) — Carrier recommends using the specified thermostat

or DDC controller to commission the unit whenever possible.

However, the blower can be started and operated without the

thermostat. To do so, locate the airflow adjustment screw

which is accessible from the inside of the control box. With

service switch in the “ON” position, turn the adjustment screw.

The unit has now been placed in manual override. Manual

override will expire when one of the following conditions is

satisfied:

• Power to the unit is cycled

• 15 minutes elapse with no change to adjustment screw

• Unit receives a control signal from the thermostat or

controller

3-Speed Jumper Field Adjustment (See Fig. 98)

— The unit

has been factory configured to produce PSC equivalent airflow

on high speed, with medium and low speed set at 80% and

60% of high, respectively. If these settings are acceptable, then

no further configuring is required.

If alternative airflows are desired, use board mounted pots

to adjust the airflow associated with each input. Each output

can be adjusted from 0 to 100% of the motor’s factory pro-

grammed operating range. Use voltmeter and airflow chart (on

control box cover) to set values. Refer to Appendix A for ad-

justment procedure.

4-Discrete Speed Potentiometer Field Adjustment, Solid

State — The unit has been factory configured to produce PSC

equivalent airflow on high speed, with medium and low speed

set at 80% and 60% of high, respectively. If these settings are

acceptable, then no further configuring is required.

Board mounted pots are provided to adjust the airflow per-

taining to each output. Each output can be adjusted from 0 to

100% of the motor’s factory programmed operating range. Use

voltmeter and airflow chart (on the control box cover) to set

values. Refer to Appendix B for adjustment procedure.

Variable Airflow for 0-10 Vdc Input (See Fig. 99)

— If a

factory provided thermostat or DDC controller is utilized, then

the unit is already correctly configured.

Carrier recommends using the specific thermostat or DDC

controller to commission the unit whenever possible. Howev-

er, the blower can be started and operated without the thermo-

stat. To do so, locate jumper 7 near the large capacitor. Move J7

from 0-10 to Man. Once moved, the onboard pots control fan

speed. To switch the fan in this configuration, place a dry con-

tact inline or on the enable wire.

START-UP

Before beginning any start-up operation, the start-up per-

sonnel should familiarize themselves with the unit, options and

accessories, and control sequence to understand the proper sys-

tem operation. All personnel should have a good working

knowledge of general start-up procedures and have the appro-

priate start-up and balancing guides available for consultation.

The building must be completely finished including doors,

windows, and insulation. All internal walls and doors should

be in place and in the normal position. In some cases, the inte-

rior decorations and furniture may influence overall system

performance. The entire building should be as complete as

possible before beginning any system balancing.

Except as required during start-up and balancing operations,

no fan coil units should be operated without all the proper duct-

work attached, supply and return grilles in place, and all access

doors and panels in place and secure.

Fig. 97 — ECM Proportional Speed Board

a42-4313

LOW

MED

HIGH

VR1

VR2

VR3

LOW

MED

HIGH

COM

CR1

POTS

Fig. 98 — 3-Speed Potentiometer Adjustment

CAUTION

Both of the start-up and servicing procedures described

below require the control box to be powered while adjust-

ments are made. Line voltage components are concealed

behind a secondary cover. However, installer should still

take all reasonable precautions.

Fig. 99 — ECM Proportional Speed Board

a42-4313

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Carrier 42C,V Manual de instalación Pagina 79

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