Carrier 48ES---A Instruction Manual download pdf (Page 23)

Proceedasfollows:

1.Removecapsfromlow-andhigh-pressureservicefittings.

2.Usinghoseswithvalvecoredepressors,attachlow-and

high-pressuregaugehosesto low- andhigh-pressure

servicefittings,respectively.

3.StartunitinCoolingModeandletunitrununtilsystem

pressuresstabilize.

4.Measureandrecordthefollowing:

a.Outdoorambient-airtemperature(°F[°C]db).

b.Liquidlinetemperature(°F[°C]).

c.Discharge(high-side)pressure(psig).

d.Suction(low-side)pressure(psig)(forreferenceonly).

5.Using"CoolingChargingCharts,"compareoutdoor-air

temperature(°F[°C]db)withthedischargelinepressure

(psig)to determinedesiredsystemoperatingliquidline

temperature(SeeTable7).

6.Compareactualliquidlinetemperaturewithdesiredliquid

linetemperature.Usingatoleranceof- 2°F(-I.I°C),add

refrigerantif actualtemperatureismorethan2°F(I.I°C)

higherthanproperliquidlinetemperature,or remove

refrigerantif actualtemperatureismorethan2°F(I.I°C)

lowerthanrequiredliquidlinetemperature.

NOTE:If theproblemcausingtheinaccuratereadingsis a

refrigerantleak,refertotheCheckforRefrigerantLeakssection.

Indoor Airflow and Airflow Adjustments

[]NIT OPERATION HAZARD

Failure to follow this caution may result in unit damage.

For cooling operation, the recommended airflow is 350 to

450 cfm for each 12,000 Btuh of rated cooling capacity. For

heating operation, the airflow must produce a temperature

rise that falls within the range stamped on the unit rating

plate.

NOTE: Be sure that all supply-and return-air grilles are open,

free from obstructions, and adjusted properly.

ELECTRICALSHOCK HAZARD

Failure to follow this warning could result in personal

iniury or death.

Disconnect electrical power to the unit and install lockout

tag before changing blower speed.

This unit has independent fan speeds for gas heating and cooling.

In addition, this unit has the field-selectable capability to run two

different cooling fan speeds: A normal cooling fan speed (350~400

CFM/Ton) and an enhanced dehumidification fan speed (As low as

320 CFM/Ton) for use with either a dehumidistat or a thermostat

that supports dehumidification.

This unit is factory-set up for use with a single cooling fan speed.

The cooling speed is marked "LOW" on the interface fan board

(IFB)(Fig. 17). The factory-shipped settings are noted in Table 8.

There are 3 additional speed tap wires available for use in either

gas heating or cooling (For color coding on the indoor fan motor

leads, see Table 6). The additional 3 speed tap wires are shipped

loose with vinyl caps and are located in the control box, near the

interface fan board (IFB) (Fig. 17).

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 8 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. 17 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 10 to the system static to determine

the correct cooling airflow speed in Table 8 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) (Fig. 17) 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.

1. Remove fan speed tap wire from the "LOW" terminal on

the interface fan board (IFB) (Fig. 17).

2. Determine correct normal cooling fan speed for unit and

application. Add the wet coil pressure drop in Table 10 to

the system static to determine the correct cooling airflow

speed in Table 8 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 8) to determine allowable

speeds for the dehumidification cooling fan speed. In Table

8, 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.

NOTE: For cooling operation, the recommended airflow is 350 to

450 CFM for each 12,000 Btuh of rated cooling capacity.

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Carrier 48ES---A Instruction Manual Page 23

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