Carrier 48EZ-A installation instructions Gas Heating Fan Speed Set-up, Continuous Fan Operation

Gas Heating Fan Speed Set-up

To change the gas heating speed:

1.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding). Table 10 shows the temperature rise associated with each fan speed for a given static pressure. Make sure that the speed chosen delivers a temperature rise within the rise range listed on the unit rating plate.

2.Remove the current speed tap wire from the “GAS HEAT” terminal on the interface fan board (IFB) (Fig.14) and place vinyl cap over the connector on the wire.

3.Connect the desired speed tap wire to the “GAS HEAT” terminal on the interface fan board (IFB).

Single Cooling Fan Speed Set-up (Dehumidification feature not used)

To change cooling speed:

1.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding). Add the wet coil pressure drop in Table 8 to the system static to determine the correct cooling airflow speed in Table 10 that will deliver the nominal cooling airflow as listed in Table 1 for each size.

2.Remove the current speed tap wire from the “LOW” terminal on the interface fan board (IFB) (See Fig. 14) and place vinyl cap over the connector on the wire.

3.Connect the desired speed tap wire to the “LOW” terminal on the interface fan board (IFB).

Two Cooling Fan Speeds Set-up (Dehumidification feature used)

IMPORTANT: Dehumidification control must open control circuit on humidity rise above set point.

Use of the dehumidification cooling fan speed requires use of either a 24 VAC dehumidistat or a thermostat which includes control of a 24 VAC dehumidistat connection. In either case, the dehumidification control must open the control circuit on humidity rise above the dehumidification set point. Dehumidification controls are available with the reverse logic; these must not be used.

1.Remove fan speed tap wire from the “LOW” terminal on the interface fan board (IFB) (See Fig. 14).

2.Determine correct normal cooling fan speed for unit and application. Add the wet coil pressure drop in Table 8 to the system static to determine the correct cooling airflow speed in Table 10 that will deliver the nominal cooling airflow as listed in Table 1 for each size.

3.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding) for the normal cooling fan speed and place desired speed tap wire on “HIGH” on the interface board.

4.Refer to airflow tables (Table 10) to determine allowable speeds for the dehumidification cooling fan speed. In Table 10, speeds that are not allowed for dehumidification cooling are shaded.

5.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding) for the dehumidification cooling fan speed and place desired speed tap wire on the “LOW” connection on the interface board (IFB). Verify that static pressure is in the acceptable range for the speed tap to be used for dehumidification cooling.

6.Use any spare vinyl plugs to cap any unused speed tap wires.

Continuous Fan Operation

When the DEHUM feature is not used, the continuous fan speed will be the same as cooling fan speed. When the DEHUM feature is used, the continuous fan will operate on IFB “LOW” speed when the DH control lead is not energized, or IFB “HIGH” speed when the DH lead is energized (see Fig. 14).

NOTE: For heat pump operation, the recommended airflow is 350 to 450 CFM for each 12,000 Btuh of rated cooling capacity.

Table 6 – Color Coding for Indoor Fan Motor Leads

Black = High Speed

Orange = Med---High Speed

Red = Med Speed

Pink = Med---Low Speed

Blue = Low Speed

GAS

HEAT

HIGH

LOW

COM

QC6

QC7

QC4

QC3

K2

K1

DCR

QCR

CDM/C

RL3

C8

R1L

Q1

D2

C

24VAC/R

RI0

QC1

JM6

RI2

Q3

C9

C4

G1JM5

RI

DL

3 AMP

OILL C2

D6

D4

G2

A7

R9

AB

A15

F1

C0

U1

C3

R4

RL4

D5

D3

C7

JW3

P3

R2

R3

R5

R6

JW7

QCB

P2

SDL

JW2

Y

Y

R

U

C

24VAC

JW4

JW1

P1

SSTZ-8

W2

Y2/

G

Y1/

C

R

DH

Y

A09058

Fig. 14 - Interface Fan Board (IFB)

48EZ -- A

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