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G-015 · REV 2 · CHECKED 2026-10-09 · MODEL v1.0.2 ▾

Drafted with AI assistance. Numbers computed by model v1.0.2 or sourced. Human review: pending (BayHeat editorial desk). Licensed review: no page-specific approval recorded.

Technical review: no page-specific licensed approval recorded.

M measured · C computed · S spec · R reference · E estimate

Electric garage heaters

Electric garage heaters span a plug-in heater you carry in from the truck to a hardwired unit heater bolted to the ceiling. Output and circuit size scale together — a bigger heater always needs a bigger breaker and thicker wire, not just a bigger price tag.

Model pick · spec-based

Comfort Zone CZ220 5,000W ceiling heater5.0 kW · 240 V / 30 A

A 5 kW ceiling heater on a 30 A circuit: enough for our example 2-car garage once it is sealed and insulated.

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Check price on Amazon
Paid linkCompare every electric class ↓

Manual: not where gasoline, paint or flammable liquids are used or stored. Indoors only, in a dry space free of combustible dust. Source ↗

The garage heater calculator sizes the exact class for your garage from its dimensions, insulation and local design temperature. This page lists every class side by side; the pages below cover one class each in depth. For one pick per situation, from a small 1-car garage to a gas-heated shop, see our garage heater picks by situation.

Size your garage free →

Which page you need

240V garage heaters

Breaker size, wire gauge and GFCI for a hardwired 4-10 kW unit, and why 4 kW doesn't fit a 20A circuit.

Portable garage heaters

What a 15A or 20A garage outlet can actually run without tripping.

Ceiling-mount garage heaters

Mounting height, throw and clearance for a 5 kW or 7.5 kW ceiling unit.

Wall-mount garage heaters

1.5 kW to 7.5 kW wall units, with the clearances from each manual.

Shop heaters

How a 240V electric unit heater compares with vented gas and diesel in a workshop.

Every electric class, side by side

Output ranges and circuits come from the same sizing engine behind the calculator, not a spec sheet we retyped by hand. Price is a range class, never a live number — check the actual price on the retailer's page before you buy.

Paid links: we earn a commission if you buy through links on this page, at no cost to you. As an Amazon Associate, BayHeat earns from qualifying purchases.

ClassOutputCircuitPriceShop
120V portable utility heater (1,500W)Linked: Comfort Zone CZ798GR3 1,500W milkhouse heater–120 V / 15 A$Check price on Amazon
Sole load on the circuit. No extension cords or power strips. Manual: attended use only, never while you're away or asleep, and not where gasoline, paint or flammable liquids are used or stored.
120V infrared/quartz wall heater (1,500W)Linked: Dr. Infrared DR-238 1,500W carbon infrared heater (wall or ceiling)–120 V / 15 A$$Check price on Amazon
Manual: the lowest part of the heater must be at least 94.5 in above the floor, wall or ceiling mounted, and a wall mount needs 15.8 in to the ceiling, so check your ceiling height first; a standard 8 ft ceiling will not meet it. Not where gasoline, paint or flammable liquids are used or stored. Plug it straight into the outlet: never an extension cord or power strip. Do not leave it unattended when in use.
240V hardwired heater (4,000W)240 V / 25 A$$Search on Amazon
Manual: not where gasoline, paint or flammable liquids are used or stored.
240V ceiling fan-forced heater (5,000W)Linked: Comfort Zone CZ220 5,000W ceiling heater240 V / 30 A$$Check price on Amazon
Manual: not where gasoline, paint or flammable liquids are used or stored. Indoors only, in a dry space free of combustible dust.
240V shop heater (7,500W)Linked: Dr. Infrared DR-975 7,500W shop heater240 V / 40 A$$$Check price on Amazon
Manual: “WARNING – RISK OF FIRE, DO NOT USE AS A RESIDENTIAL OR HOUSEHOLD HEATER.” Also not where gasoline, paint or flammable liquids are used or stored. Ask Dr. Infrared whether your garage counts as residential before you buy.
240V unit heater class (10,000W)Linked: Dr. Infrared DR-910F 10,000W 240V hardwired shop heater240 V / 60 A$$$Check price on Amazon
Manual: “WARNING – RISK OF FIRE, DO NOT USE AS A RESIDENTIAL OR HOUSEHOLD HEATER.” Also not where gasoline, paint or flammable liquids are used or stored. Ask Dr. Infrared whether your garage counts as residential before you buy.
DIY pre-charged mini-split, 12k class (115V)–120 V / 20 A$$$$Search on Amazon
Refrigerant work (vacuum, charge, line-set brazing) needs EPA Section 608 certification -- have it installed by a licensed HVAC contractor.
Mini-split heat pump, 12-24k class (230V)Linked: Della Optima 12,000 BTU 230V mini-split heat pump (heat + cool)–240 V / 30 A$$$$Check price on Amazon
Refrigerant work (vacuum, charge, line-set brazing) needs EPA Section 608 certification -- have it installed by a licensed HVAC contractor.

Don't buy by wattage alone

A plug-in heater keeps a workbench warm; it can't cover a whole detached garage, and running two or three of them to make up the difference means running two or three circuits. The opposite trap is a 240V heater that looks smaller because its wattage number is lower — a unit still needs a dedicated 25A circuit, not the 20A circuit already run to most garages. The 240V page shows exactly why. For a workshop, the shop heater guide weighs an electric unit heater against gas and diesel.

How big is "enough"? A worked example

A 24×24 ft attached two-car garage in Chicago, R-13 walls, one uninsulated steel door, average drafts, needs about () to hold 55°F on the coldest design day — grade on the envelope scale below.

Heat escapesYour garage: DHolds heat
Ceiling
34%
Air leaks
24%
Big door
23%
Slab edge
9%
Walls
8%
Windows
3%
House wall
-3%
Service door
2%
FIG. 1 Where your heat goes, sorted largest first.

The planner's electric answer for that load is 2 heaters of the 240V ceiling fan-forced heater (5,000W) class, each on its own breaker and 10 AWG copper. That is not the smallest thing on the shelf.

Safety

Every 120V class here still needs GFCI protection on the outlet it plugs into (); a hardwired 240V unit isn't a receptacle, so that rule governs the garage's outlets, not the heater itself. Either way the circuit is sized for a continuous load (), not just the heater's running current. Your electrician and your local code edition govern.

General information. Your electrician, gas fitter, local code and the heater's manual govern.

Related

Sources

  1. [1] NFPA 70, National Electrical Code, 2023, NFPA. Retrieved 2026-09-25.
  2. [2] Comfort Zone CZ798CA2 milkhouse heater instruction manual (Canadian Tire copy), Comfort Zone / Canadian Tire. Retrieved 2026-10-09.
  3. [3] Heat Storm Tradesman HS-1500-TT owner's manual, Heat Storm. Retrieved 2026-09-25.
  4. [4] Comfort Zone CZ220 Series ceiling mounted heater owner's manual, Comfort Zone (Lowe's copy). Retrieved 2026-10-09.
  5. [5] Dr. Infrared Heater DR-975 owner's manual, Dr. Infrared Heater. Retrieved 2026-09-30.
  6. [6] Dr. Infrared Heater DR-238 carbon infrared heater owner's manual, Dr. Infrared Heater. Retrieved 2026-09-30.
  7. [7] Dr. Infrared Heater DR-910F 10,000W 240V wall/ceiling garage heater owner's manual, Dr. Infrared Heater. Retrieved 2026-09-30.
  8. [8] Section 608 of the Clean Air Act: stationary refrigeration and air conditioning, US Environmental Protection Agency. Retrieved 2026-10-09.
Size my garage — 60 s