Limit Switch

and Shield

C08284

Fig. 28 - Limit Switch Location

Fuel Types and Pressures

Natural Gas — The 48TC unit is factory-equipped for use with Natural Gas fuel at elevation under 2000 ft (610 m). See section Orifice Replacement for information in modifying this unit for installation at elevations above 2000 ft (610 m).

Gas line pressure entering the unit’s main gas valve must be within specified ranges. Adjust unit gas regulator valve as required or consult local gas utility.

Table 4 – Natural Gas Supply Line Pressure Ranges

UNIT MODEL

UNIT SIZE

MIN

MAX

48TC

All

4.0 in. wg

13.0 in. wg

(996 Pa)

(3240 Pa)

 

 

 

 

 

 

Manifold pressure is factory-adjusted for NG fuel use. Adjust as required to obtain best flame characteristic.

Table 5 – Natural Gas Manifold Pressure Ranges

UNIT

UNIT

HIGH

LOW

RANGE

MODEL

SIZE

FIRE

FIRE

 

 

 

 

 

 

48TCD,S

 

3.5 in. wg

1.7 in. wg

2.0---5.0 in. wg (Hi)

48TCE,R

All

(872 Pa)

(423 Pa){

(498---1245 Pa)

48TCF,T

 

 

 

 

 

 

 

 

 

 

48TCL

 

3.5 in. wg

 

2.0---5.0 in. wg (Hi)

48TCM

All

NA

(872 Pa)

(498---1245 Pa)

48TCN

 

 

 

 

 

 

 

 

 

 

 

NA: Not Available

{3 Phase models only

Liquid Propane — Accessory packages are available for field-installation that will convert the 48TC unit (except low NOx model) to operate with Liquid Propane (LP) fuels. These kits include new orifice spuds, new springs for gas valves and a supply line low pressure switch. See section on Orifice Replacement for details on orifice size selections.

Low NOx models include specially-sized orifices and use of different flue flow limits and tube baffles. Because of these extra features, conversion of these models to LP is not recommended.

Fuel line pressure entering unit gas valve must remain within specified range.

Table 6 – Liquid Propane Supply Line Pressure Ranges

UNIT MODEL

UNIT SIZE

MIN

MAX

48TCD,E,F

All

11.0 in. wg

13.0 in. wg

48TCS,R,T

(2740 Pa)

(3240 Pa)

 

 

 

 

 

48TCL,M,N

All

NA

NA

 

 

 

 

Manifold pressure for LP fuel use must be adjusted to specified range. Follow instructions in the accessory kit to make initial readjustment.

Table 7 – Liquid Propane Manifold Pressure Ranges

UNIT MODEL

 

UNIT SIZE

HIGH FIRE

LOW FIRE

 

 

48TCD,S

 

 

10.0 in. wg

5.0 in. wg

 

 

48TCE,R

 

All

 

 

 

(2490 Pa)

(1245 Pa){

 

 

48TCF,T

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

48TCL,

 

 

 

 

 

 

 

 

 

 

 

 

48TCM,

 

All

NA

NA

 

48TC

48TCN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NA: Not Available

 

 

 

 

 

{3 Phase models only

Supply Pressure Switch — The LP conversion kit includes a supply low pressure switch. The switch contacts (from terminal C to terminal NO) will open the gas valve power whenever the supply line pressure drops below the setpoint. See Fig. 29 and Fig. 30. If the low pressure remains open for 15 minutes during a call for heat, the IGC circuit will initiate a Ignition Fault (5 flashes) lockout. Reset of the low pressure switch is automatic on rise in supply line pressure. Reset of the IGC requires a recycle of unit power after the low pressure switch has closed.

C08238

Fig. 29 - LP Low Pressure Switch (Installed)

IGC

LP LPS

 

 

 

 

 

BRN

C

NO

BRN

J2-11

 

 

C

 

 

 

IGC

 

 

MGV

 

 

 

J2-12

GRA

 

 

 

 

 

TSTAT

 

 

 

W2

PNK

 

 

C08285

Fig. 30 - LP Supply Line Low Pressure Switch Wiring

23

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Carrier 48TCA04---A12 appendix Fuel Types and Pressures, Natural Gas Supply Line Pressure Ranges

48TCA04---A12 specifications

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