How big is a gas furnace?#
A residential gas furnace comes in a cabinet 14.5 to 24.5 inches wide, all standing 34 to 40 inches tall and 28 to 30 inches deep. The table below sorts the narrow, mid, and wide cabinets, which are chosen by heating capacity.
Gas furnace dimensions by configuration#
| Configuration | Cabinet width (in) | Height (in) | Depth (in) | Best for |
|---|---|---|---|---|
| Narrow-cabinet gas furnace | 14.5 | 34–40 | 28–30 | a tight closet or a lower-capacity home |
| Mid-cabinet gas furnace | 17.5–21 | 34–40 | 28–30 | the most common furnace sizes |
| Wide-cabinet gas furnace | 24.5 | 34–40 | 28–30 | a high-capacity or high-efficiency system |
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Installation clearances for a gas furnace#
- Front service clearance: 24–30 in in of front access a gas furnace needs to pull the blower and change the filter.
- Combustion clearance: 1–6 in in around a gas furnace cabinet to nearby combustibles, per the nameplate listing.
- Return and supply: A gas furnace needs a return-air drop below and a supply plenum above, so leave cabinet room at both ends.
- Evaporator coil: An upflow gas furnace stacks an evaporator coil on top, adding height that must clear the plenum and any joists.
Will your gas furnace fit? Clearances and door swing#
A gas furnace is sized by its cabinet width, so match that to the closet or platform first — the height and depth barely change across models. Leave 24 to 30 inches of clear front access so a technician can pull the blower and swap the filter, since the burner and blower service from the front. Combustion is the part a room dehumidifier or air handler never has to worry about: keep 1 to 6 inches to nearby combustibles per the furnace's nameplate listing, because the cabinet runs a real flame. The return-air drop connects below and the supply plenum above, so leave cabinet room at both ends of the vertical run. If it is an upflow furnace paired with cooling, an evaporator coil stacks on top and adds height that has to clear the plenum and any joists above.
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Gas furnace sizes by type: narrow-cabinet gas furnace, mid-cabinet gas furnace, wide-cabinet gas furnace#
The three cabinets are picked by output. The narrow-cabinet gas furnace, just 14.5 inches wide, fits a tight closet or a lower-capacity home where floor space is scarce. The mid-cabinet gas furnace, 17.5 to 21 inches wide, covers the most common heating sizes and is what most homes actually use. The wide-cabinet gas furnace, 24.5 inches across, houses a high-capacity or high-efficiency system with a larger heat exchanger and blower. All three keep the same 34 to 40 inch height and 28 to 30 inch depth, so the closet or platform only has to accommodate the width you choose. Size to the home's heating load, then confirm the cabinet width clears its space.
Gas furnace dimensions: common questions#
How wide is a residential gas furnace?#
A residential gas furnace is 14.5 to 24.5 inches wide, and that width is how furnaces are sized. Narrow cabinets serve small homes, mid cabinets are the most common, and the widest handles high-capacity systems.
How tall is a gas furnace cabinet?#
A gas furnace cabinet stands 34 to 40 inches tall across every width. An upflow furnace paired with cooling adds an evaporator coil on top, which increases the total stacked height.
How much service clearance does a furnace need in front?#
Plan 24 to 30 inches of clear front access so a technician can remove the blower and change the filter. The burner and blower all service from the front, so that access is essential.
What is the narrowest gas furnace cabinet?#
The narrowest gas furnace cabinet is 14.5 inches wide, made for a tight closet or a lower-capacity home. Wider cabinets step up to 17.5 to 21 inches and 24.5 inches for more output.
How deep is a gas furnace?#
A gas furnace is 28 to 30 inches deep regardless of cabinet width. Leave the front access clear in addition to that depth for filter and blower service.
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