Carrier 42 SERIES specifications Electric Heat, Heater Construction, Heater Electrical Data

ELECTRIC HEAT

Application Ð Electric heaters are available for in-stallation on Carrier fan coil units in the following applications.

TOTAL ELECTRIC HEAT Ð This system provides com- plete heating during the heating season; no boiler is re- quired. Heating and cooling are now available on an indi- vidual basis throughout the year with a 2-pipe system.

Chilled water is used for cooling and the electric heater is used for heating. Room controls can be supplied for either manual or automatic changeover.

AUXILIARY ELECTRIC HEAT Ð This system is used for heating between seasons or during the cooling season when chilled water is being circulated. Individual room controls are supplied to provide electric heat only when chilled water is being circulated through the system. Water ¯ow through the unit is shut off when the heater is turned on.

During the winter heating season, heating is provided by hot water circulated through the system. A changeover device locks out the electric heat when the hot water is circulated.

Heater Construction

STRIP HEATERS Ð Used with Model 42C ceiling units, Model 42D ducted units and Model 42S stack units.

These heaters consist of coils of the highest grade resistance wire, insulated by ceramic insulators in alumi- nized brackets.

All heaters except those used in 42S stack units are po- sitioned on the incoming (preheat) side of the unit coil. On

MODEL 42V VERTICAL UNIT

WITH ELECTRIC SHEATH HEATER

42S stack units, the strip heater is located in the fan dis- charge on the leaving side of the coil.

SHEATH HEATERS Ð Used with Model 42V vertical units. These heaters consist of the highest grade resistance wire, centered in a 1¤2-in. diameter copper-plated steel sheath. The wire is insulated from the sheath by magnesium oxide pow- der packed around it. To increase the heater surface exposed to air, a 11¤4-in. OD ®n of copper-plated steel is wound around the sheath in a continuous spiral that makes 5 turns per lin- eal inch. Sheath and ®n are permanently bonded together by copper brazing.

The heaters are positioned on the leaving (reheat) side of the unit coil. On special units with high efficiency motors, a strip heater will be installed in the fan discharge on the in- coming (preheat) side of the unit coil.

Heater Electrical Data

1.Load voltage may be 120, 208, 240 or 277 volts. For unit size and kW limitations, refer to the speci®c unit catalogs.

2.All heaters are single stage and single phase.

3.Unless a single power-source option is selected, the elec- tric heat units require 2 separate power sources. With the single power-source option, only one line circuit need be brought into the unit. Fuse protection is added to the motor/ control circuit to protect these components. This is sepa- rate from the ®eld-furnished total unit overcurrent protection.

MODEL 42C CEILING UNIT

WITH ELECTRIC STRIP HEATER

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