Carrier WeatherMaster® High-Efficiency Single-Packaged Rooftop Units 48HC 48HC High Efficiency Gas Heat Electric Cooling Packaged Rooftop with EnergyX System 15 to 25 Nominal Tons
Summary
This guide provides comprehensive technical specifications, written in Masterformat, for packaged rooftop HVAC units featuring gas heat and electric cooling (15–25 nominal tons). It details every aspect of installation requirements, including specialized insulation standards, advanced instrumentation, and robust control systems. Ideal for architects, mechanical engineers, and contractors, this manual ensures compliance with modern energy codes (like ASHRAE 90.1) by specifying controls for IAQ management, smoke detection, safety interlocks, and complex staging capabilities for professional commercial construction projects.
Page 1 Text Content
GUIDE SPECIFICATIONS - 48HC*D17-28
Note about this specification: These specifications are written in “Masterformat” as published by the Construction Specification Institute. Please feel free to copy this specification directly into your building spec. Gas Heat/Electric Cooling Packaged Rooftop HVAC Guide Specifications Size Range: 15 to 25 Nominal Tons Section Description 23 06 80 Schedules for Decentralized HVAC Equipment 23 06 80.13 Decentralized Unitary HVAC Equipment Schedule 23 06 80.13.A. Rooftop unit schedule 1. Schedule is per the project specification requirements. 23 07 16 HVAC Equipment Insulation 23 07 16.13 Decentralized, Rooftop Units: 23 07 16.13.A. Evaporator fan compartment: 1. Interior cabinet surfaces shall be insulated with a minimum 1/2-in thick, minimum 1 1/2 lb density, flexible fiberglass insulation bonded with a phenolic binder, neoprene coated on the air side. 2. Insulation and adhesive shall meet NFPA 90A requirements for flame spread and smoke generation. 23 07 16.13.B. Gas heat compartment: 1. Aluminum foil-faced fiberglass insulation shall be used. 2. Insulation and adhesive shall meet NFPA 90A requirements for flame spread and smoke generation. 23 09 13 Instrumentation and Control Devices for HVAC 23 09 13.23 Sensors and Transmitters 23 09 13.23.A. Thermostats 1. Thermostat must a. energize both “W” and “G” when calling for heat. b. have capability to energize 2 different stages of cooling, and 2 different stages of heating. c. include capability for occupancy scheduling. 23 09 23 Direct-digital Control system for HVAC 23 09 23.13 Decentralized, Rooftop Units: 23 09 23.13.A. Controls and Safeties 1. Unit Comfort Link Controls: a. Scrolling Marquee display. b. CCN (Carrier Comfort Network™) capable. c. Unit control with standard suction pressure transducers and condensing temperature thermistors. d. Shall provide a 5°F temperature difference between cooling and heating set points to meet ASHRAE 90.1 Energy
Standard. e. Shall provide and display a current alarm list and an alarm history list. f. Automatic compressor redundancy on units without Humidi-Mi Zer system. g. Service run test capability. h. Shall accept input from a CO2 sensor (both indoor and outdoor). i. Configurable alarm light shall be provided which activates when certain types of alarms occur. j. Compressor minimum run time (3 minutes) and minimum off time (5 minutes) are provided. k. Service diagnostic mode. l. Economizer control (optional). m. Multiple capacity stages. n. Unit shall be complete with self-contained low-voltage control circuit. o. Unit shall have 0°F low ambient cooling operation.
2. Safeties: a. Unit shall incorporate a solid-state compressor lockout that provides optional reset capability at the space
thermostat should any of the following safety devices trip and shut off compressor: (1.) Compressor lockout protection provided for either internal or external overload. (2.) Low-pressure protection.
Page Summary Contents For Carrier WeatherMaster® High-Efficiency Single-Packaged Rooftop Units 48HC 48HC High Efficiency Gas Heat Electric Cooling Packaged Rooftop with EnergyX System 15 to 25 Nominal Tons
Manual Details
| Brand | Carrier |
|---|---|
| Pages | 10 |
| File Size | 119.27 KB |
| Published | June 05, 2026 |
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Frequently Asked Questions
What insulation materials are required for the evaporator fan and gas heat compartments?
The evaporator needs minimum 1/2-in thick fiberglass insulation bonded with a phenolic binder (neoprene coated on air side). The gas compartment requires aluminum foil-faced fiberglass insulation.
What features must a thermostat have for decentralized HVAC equipment?
It must energize both “W” and “G,” service two stages of cooling/heating, and support occupancy scheduling.
How does the unit maintain safety during compressor operation?
Safety systems include solid-state lockout protection (overload, low/high pressure), freeze protection, high-pressure monitoring, and loss of charge protection.
What are the minimum operating time limits for the compressor?
The compressor must provide a 3-minute minimum run time and a 5-minute minimum off time.