GENERAL AIRSTAGE Electric Furnace | 4 Tons | Montreal, Laval, Longueuil, South Shore and North Shore

GENERAL AIRSTAGE AMUG48LMAS 48,000 BTU Electric Furnace with Heat Pump (48LMAH1M System): Four Tons in a Narrow Mechanical Room

When a bungalow has been extended, the original electric furnace often serves more rooms than it did at the start, while the mechanical room has not grown with the house. The 48LMAH1M system replaces that furnace with an installation that heats first by heat pump: the AMUG48LMAS multi-position air handler on the ductwork, the AOUH48LMAH1 outdoor unit outside, and an electric kit as backup.

Fujitsu AIRSTAGE sells exactly this pair, under the same model numbers; the manufacturer’s documentation and the warranty are shared by both brands. Only the manufacturer’s name over the door has changed: Fujitsu General Limited traded its name for GENERAL Inc. on January 1, 2026.

Two facts before going further. On the cold side, the AOUH48LMAH1 belongs to the manufacturer’s “extra-low-temperature” range, and the system heats down to −26 °C. On the other hand, it is not ENERGY STAR certified, and Hydro-Québec’s LogisVert list does not include it: no grant to plan for.

GENERAL or Fujitsu AIRSTAGE: the same machine

Fujitsu General Limited has belonged since August 2025 to Paloma Rheem Holdings, the group that has overseen Rheem since 1988, and has carried the corporate name GENERAL Inc. since the start of 2026. In Kawasaki, Japan, the head office and R&D have not changed address, and neither have the factories. In the AIRSTAGE range, every model number stays the same, and the warranty follows the same program. In Canada, sales passed to Rheem Canada in February 2026, but we still source through Groupe Master, and we keep our AIRSTAGE Elite Plus installer status.

The Fujitsu name will leave the boxes gradually. In the meantime, we keep both pages side by side, and the following table repeats every value on both sides, so that a gap between two quotes cannot be explained by a difference in equipment.

Under the Fujitsu brand, this system’s twin appears on the Fujitsu AIRSTAGE 4-ton electric furnace page.

Let us start with space, since space decides. The AMUG48LMAS stands 57 in. high; on the floor, it takes up 21 in. by 21.69 in. The manufacturer requires clearance on three sides, at a minimum, and 21 in. in front for service. In a narrow room, that front space is what gets negotiated: neither the door, nor the water heater, nor the neighbouring electrical panel should encroach on it.

Before quoting, we measure the room as it really is: width between the walls, height under the joists, door swing, position of the floor drain, the water heater and the electrical panel. If the front of the unit cannot stay clear, the quote says so, along with the solution we propose.

When the room truly leaves no space, the multi-position design opens other options. The unit can lie horizontally in a crawl space or blow in downflow from a closet; the downflow kit and the horizontal right kit are part of the delivery, at no cost. We choose the position with you, based on the duct layout.

The extension also raises the question of the ductwork. If the added rooms are connected to extensions of the original ducts, the air has to travel a long way to reach them. The AMUG48LMAS offers a maximum airflow of 1,640 CFM, high allowable static pressure (1.0 in. WC at most) and adaptive control for the fan motor. If the extension never had grilles and heats with baseboards, we look with you at whether extending the ductwork there is worth it; the branches and grilles to add are decided during the visit.

In heating, the manufacturer rates the system at 51,000 BTU/h at nominal conditions, against 45,500 BTU/h in cooling. AHRI certificate 207657378, for its part, publishes 34,400 BTU at −8 °C, then 51,000 BTU with a COP of 1.92 at −15 °C; these are two test points, each with its own conditions, and we do not set them against each other. The HSPF2 is 10.0, the SEER2 16.6 and the EER2 8.8. Heating continues down to −26 °C.

On days when the heat pump is no longer enough for a house this size, the electric backup heat kit, original manufacturer equipment installed on site inside the unit’s cabinet, adds its heat to the heat pump’s; below −26 °C, it heats alone. At commissioning, the refrigeration technician checks that the two sources hand off to each other properly.

On the program side, there is nothing to claim: the 48LMAH1M does not carry ENERGY STAR certification, is not recognized as cold climate and is absent from the LogisVert list as of October 27, 2026. We are putting it in writing now so that your comparison of quotes happens on equal terms.

An extended bungalow often collects other equipment over the course of renovations. The external input/output interface, available as an option, allows the system to be interlocked with third-party systems. The heat pump, for its part, is fully communicating with the air handler, and Wi-Fi is optional.

If the mechanical room adjoins a bedroom or an office, the door and the insulation matter: the indoor unit runs between 29 and 47 dB(A) depending on speed. Outside, the AOUH48LMAH1 (38.19 × 14.56 × 52.5 in.) is rated at 54.0 dB(A); a pad or a bracket places it on the side of the lot where it bothers people least, out of reach of the snow sliding off the roof.

In practical terms, the job includes:

• a survey of the mechanical room and the ductwork, including the extension’s branches;
• removal of the electric furnace and installation of the AMUG48LMAS on the plenum, existing or new;
• installation of the backup kit and of a filter access panel that stays clear;
• the cable, the drain, the 208/230 V supply and the refrigerant line (3/8 and 5/8 in. diameters);
• commissioning by a refrigeration technician.

In a narrow room, maintenance is settled at the design stage. A filter that cannot come out without moving the water heater ends up forgotten; so we put the access panel on the clear side and leave the drain visible. The compressor is warranted for 12 years, the parts too, labour for 6 years; for exact dimensions, the manufacturer’s technical document, in French and English versions, comes with the listing.

The 48LMAH1M suits:

• the large extended bungalow whose electric furnace feeds the whole duct system, old and new;
• the owner who wants a 4-ton size heating down to −26 °C and accepts doing without a grant;
• less so the mechanical room where the front of the unit cannot stay clear and no other position is possible.

Bordeaux-Cartierville: have your mechanical room measured before replacing the furnace

In Bordeaux-Cartierville, our visit starts where space is tightest: the mechanical room, tape measure in hand. We then follow the ducts to the rooms of the extension, and outside we locate the spot for the outdoor unit. You receive a free quote that specifies the position chosen for the unit and the service space kept clear.

Call 514 316-2973. As an HVAC contractor, AirGreen goes everywhere in Montreal, to Laval and Longueuil, as well as to the South Shore and the North Shore.