Carrier WeatherMaster® 48GC Gas Heat/Electric Cooling Rooftop Unit – Supplied & Professionally Installed by 4Most Energy
The WeatherMaster® 48GC is a single-package gas heating/electric cooling rooftop unit engineered for commercial and light-industrial buildings across the 6.0 to 12.5 nominal ton range. Two tandem scroll compressors deliver two-stage cooling on a Puron® (R-410A) refrigeration circuit rated up to 17.7 IEER and 12.2 EER, while the patented EcoBlue™ vane axial indoor fan system — direct-drive, electronically commutated, with 75% fewer moving parts than a belt-drive forward-curved fan — cuts fan energy up to 40% and eliminates belt, pulley, and bearing maintenance. Two-stage induced-draft gas heat is available in low, medium, and high input configurations from 55/41 MBH up to 250/205 MBH input/output per stage, with aluminized or stainless steel tubular heat exchangers, direct-spark ignition, and redundant main gas valves delivering 81–82% thermal efficiency. All 48GC units meet DOE 2023 minimum efficiency standards and ASHRAE 90.1/IECC requirements, and are AHRI 340/360 certified and UL listed.
Rated performance depends entirely on correct field installation. Ontario gas heat installations require TSSA gas technician sizing of the gas line and meter to the unit’s natural gas supply pressure (4–13 in. wg) or propane conversion kit, combustion and gas-train testing at start-up, and induced-draft venting configured per the unit’s vertical or field-convertible horizontal discharge orientation. Roof curb selection (14 in. or 24 in.), structural load review, thru-the-base gas and electrical connections, and ESA-compliant electrical hookup sized to the unit’s voltage (208-230/460/575V, 3-phase) and MCA/MOCP rating are equally code-driven and equally easy to get wrong without an experienced crew. 4Most Energy is a certified installer for rooftop unit installation Toronto, packaged RTU replacement GTA, and Carrier WeatherMaster 48GC installation Ontario projects, providing licensed gas technician near me–level combustion testing and commissioning and ENERGY STAR–calibre rooftop unit Toronto service standards on every job — so the IEER and thermal efficiency figures on the nameplate are what the building actually gets, not just what’s on the spec sheet.
Warranty
Carrier backs the WeatherMaster® 48GC with a 3-year limited parts warranty from the factory. 4Most Energy handles warranty registration and start-up documentation on your behalf.
Documents
Why Install the Carrier WeatherMaster® 48GC with 4Most Energy?
- EcoBlueTM vane axial indoor fan system — direct-drive ECM motor, 75% fewer moving parts, up to 40% better efficiency, and slow ramp-up for quieter, more reliable operation than belt-drive forward-curved fans.
- Two-stage cooling with tandem scroll compressors — fully active evaporator coil and mixed air temperature protection on all models, with internal line-break overload protection and rubber-grommet mounting.
- Two-stage induced-draft gas heat — low, medium, or high input configurations with direct-spark ignition, redundant main gas valve, and dimpled heat exchanger tubes for improved heat transfer; standard aluminized or optional stainless steel (Type 409) heat exchanger for high-humidity or corrosive environments.
- Up to 17.7 IEER with 2-speed indoor fan motor — no variable frequency drive required to hit this efficiency tier.
- Optional Humidi-MiZer® adaptive dehumidification system — sub-cooling and hot gas reheat modes for improved part-load humidity control (07–14 sizes).
- Optional SystemVuTM intelligent controller — large multi-line display, USB data port, and built-in i-Vu®, CCN, and BACnet compatibility for building automation integration.
- New unit control board with dial-and-switch indoor fan adjustment, phase reversal/phase loss protection, and quick LED run/alert/fault status.
- Tool-less filter access door and no-strip screw collars throughout for faster service and field repairs.
- Field-convertible horizontal airflow on all models (factory kit required on size 14 only), reducing replacement complexity on legacy curbs.
Carrier 48GC Series Specifications
| Model | Nominal Tons | Net Cooling (MBH) |
EER | IEER (2-speed fan) |
Rated CFM | Sound (dBA, A-wtd) |
Base Unit Weight (lb) |
|---|---|---|---|---|---|---|---|
| 48GC*07 | 6.0 | 72.0 | 12.2 | 17.5 | 2,400 | 82 | 775 |
| 48GC*08 | 7.5 | 90.0 | 12.0 | 17.5 | 3,000 | 82 | 893 |
| 48GC*09 | 8.5 | 96.0 | 11.8 | 17.3 | 3,400 | 82 | 893 |
| 48GC*12 | 10.0 | 114.0 | 11.4 | 17.2 | 3,250 | 87 | 1,037 |
| 48GC*14 | 12.5 | 146.0 | 12.0 | 16.5 | 5,250 | 83 | 1,390 |
Ratings per AHRI Standards 340/360 at 80°F/67°F wb indoor, 95°F db outdoor.
Carrier Gas Heat Option Specifications
| Gas Heat Option (Input/Output MBH) |
07 | 08 | 09 | 12 | 14 |
|---|---|---|---|---|---|
| Low | 55/41 – 72/59 | 90/66 – 125/102.5 | 90/66 – 125/102.5 | 120/98 – 180/148 | 120/98 – 180/148 |
| Medium | 90/66 – 125/102.5 | 120/98 – 180/148 | 120/98 – 180/148 | 180/146 – 224/181 | 180/146 – 224/181 |
| High | 115/96 – 150/123 | 180/146 – 224/181 | 180/146 – 224/181 | 200/164 – 250/205 | 192/156 – 240/194 |
Thermal efficiency 81–82% across all gas heat configurations. Natural gas and propane input/output identical; propane requires field-installed conversion kit. Heat exchanger available in standard aluminized or optional Type 409 stainless steel.
The 48GC is sized first by cooling load (6.0–12.5 nominal tons) using a proper Manual N/commercial load calculation — not by matching the tonnage of the unit being replaced, since older rooftop units on the same curb were frequently oversized by the standards of their era. Gas heat input (low/medium/high, by stage) should be selected against the building’s actual heat loss calculation and the temperature rise range specified for the unit and airflow setting, not defaulted to the highest available input. Sound-sensitive sites (schools, offices, mixed-use buildings with rooftop-adjacent occupied space) should weigh the 82–87 dBA outdoor sound ratings across sizes into curb placement and unit selection. 4Most Energy performs load calculation, gas capacity verification, and roof structural review as part of every quote before ordering.
Carrier WeatherMaster Installation Checklist
| Step # | Phase Name | Key Requirements & Technical Details |
|---|---|---|
| Step 1 | Site Assessment | Existing unit and curb inspection, gas service and meter capacity check, electrical service review, and roof structural/access evaluation. |
| Step 2 | Load Calculation & Sizing | Confirm correct tonnage, gas heat input level, airflow configuration (vertical or horizontal), and control option (standard thermostat or SystemVu™). |
| Step 3 | Rigging & Crane Setup | WeatherMaster’s lighter base-rail design and multi-point rigging shackles simplify crane placement onto the existing or new roof curb. |
| Step 4 | Roof Curb & Structural Prep | Install or verify 14 in./24 in. roof curb, full-perimeter seal, and structural support for the unit’s operating weight. |
| Step 5 | Gas Line & Venting Connection | Licensed TSSA gas technician sizes and connects the gas line (thru-the-base or side connection), verifies supply pressure, and configures induced-draft venting for the unit’s discharge orientation. |
| Step 6 | Electrical Connection | ESA-compliant hookup to the building’s disconnect, sized to the unit’s voltage, phase, and MCA/MOCP rating, with thru-the-base or side electrical connections as specified. |
| Step 7 | Ductwork Tie-In | Supply and return duct connection matched to vertical or horizontal discharge, with turning vanes and sealed transitions. |
| Step 8 | Commissioning | Combustion analysis and gas train test, refrigerant charge verification, airflow and temperature rise confirmation, and control system setup (thermostat or SystemVu™/BAS integration), with warranty registration filed. |
| Step 9 | Final Walkthrough | Filter access, service clearances, and control operation demonstrated before the crew leaves site. |
Carrier’s standard coverage on the WeatherMaster® 48GC is a 3-year limited parts warranty from the factory. 4Most Energy completes and files the required start-up and combustion test documentation to keep warranty coverage valid.
Routine maintenance is straightforward by design: the EcoBlueTM direct-drive fan requires no belts, pulleys, or shaft bearings to inspect or replace, and the tool-less filter door simplifies the most frequent service task. Carrier recommends annual combustion testing and gas train inspection on all gas heat units, condenser coil cleaning, and condensate drain pan/trap inspection. 4Most Energy offers scheduled maintenance plans covering filter changes, combustion analysis, refrigerant circuit checks, and control board diagnostics via the unit’s built-in LED status indicators.
Service Area
Greater Toronto Area (GTA) and surrounding regions
Toronto, Markham, Richmond Hill, Vaughan, Aurora, Newmarket, Scarborough, Brampton, and Mississauga.
Extended Service Area: Stouffville, Oshawa, Barrie, Orangeville, Hamilton, St. Catharines, Guelph, Kitchener.
Frequently Asked Questions
Can the 48GC run on propane instead of natural gas?
Yes — a field-installed propane conversion kit is available for all 48GC sizes, using the same input/output ratings as the natural gas configuration at elevations up to 2000 ft.
Is the 48GC a direct replacement for our existing rooftop unit?
In most cases the unit is designed to fit on legacy Carrier R-410A curbs and many competitor curbs without modification, though 4Most Energy always verifies curb dimensions, gas/electrical connection points, and structural load before ordering.
How loud is the 48GC, and will it be a problem for occupied space below the roof?
A- weighted outdoor sound ranges from 82 dBA (sizes 07–09 and 14) to 87 dBA (size 12). For sound-sensitive locations, 4Most Energy can advise on curb placement, sizing alternatives, or accessory sound treatment during the quote.
What’s the difference between the standard aluminized and optional stainless steel heat exchanger?
The stainless steel (Type 409) heat exchanger is recommended where mixed air entering the heat exchanger may drop below 45°F or where airborne contaminants or high
humidity would otherwise shorten the life of a standard aluminized exchanger common in kitchens, pools, and paper/print facilities.
Does the 48GC support building automation system integration?
Yes — the optional SystemVuTM controller provides built-in i-Vu®, BACnet, and Carrier Comfort Network (CCN) capability, or the unit can operate on a conventional thermostat with standalone controls.
