Mini-split vs electric garage heater

• You use the shop in summer too. A garage in a hot climate is a sauna in the afternoon. A mini-split cools it; a heater does nothing. The garage mini-split cooling calculator sizes the load.
• Rust is a problem. Cast-iron tables and steel tools rust where humid air meets cold metal. A mini-split's dry mode and steady temperature help. Pair it with Boeshield T-9 on the tables.
• You run the heat all winter. A heat pump uses less electricity per unit of heat than resistance, so the higher entry price is repaid over many hours. Check the listing for how the heating capacity falls with outdoor temperature.
• You own the house. The outdoor unit and the hole through the wall are a permanent change.

• You use the garage on cold weekends only. A few dozen hours a year does not repay a mini-split.
• You rent or you will move. A ceiling heater comes down with a few screws. A mini-split leaves a hole in the wall.
• You have a 240V circuit and no wall to spare. A heater plugs into a 14-50 receptacle. A mini-split needs the wall for the head and the outside for the condenser.
• The shop is dusty. A mini-split's indoor filter loads with fine dust and the coil can foul. A heater with no filter has nothing to clog, as long as it is kept clean and clear.

A mini-split is a better machine, and it is a bigger decision. Its advantage is that it is a heat pump. A heat pump moves heat from outside to inside, so it delivers more heat energy than the electrical energy it uses, within the temperature range it is built for. A resistance heater cannot do that; every watt in is a watt of heat out, no more. At 3.412 BTU per watt, a 7,500 W heater gives about 25,590 BTU per hour, and it will always cost the same to run per BTU.

The limit is cold. A heat pump's output falls as the outdoor temperature falls, and the rating that matters is the one the manufacturer gives for low outdoor temperatures. Our briefs have no such figure for the Albott or the MRCOOL unit, so we do not quote one; read the listing, and if you live where it gets very cold, treat the mini-split as the mild-weather heater and keep a backup.

The title of the Albott unit says 12,000 BTU, 115V, with a Fast-Fit set. The MRCOOL DIY Select in our catalog is also a 12,000 BTU, 115V heat pump per its title. Compare: the 7,500 W resistance heater puts out about twice the nominal BTU of the 12,000 BTU unit's cooling rating, which is why a resistance heater of that size heats a cold bay faster even though it costs more to run.

Neither heater beats a leaky building. An overhead door is the biggest hole: a bare steel door and its worn seals lose more heat than the walls. A mini-split cannot beat an open door, as the cooling calculator notes for the 9 ft and 16 ft doors. Insulate the door first with the NASA TECH two-car kit or the Reach Barrier single-door kit, replace the bottom seal, and caulk the sill plate. Then size the unit.

The size comes from the garage heater BTU calculator for heat and the cooling calculator for summer. Our sizing pages give the figure for each standard bay: the mini-split sheet for a 22 x 22 ft garage and the heater sheet for the same bay. A 12,000 BTU mini-split is a good fit for a one-car bay and a stretch for a two-car bay, and the sheets show the load at three insulation levels and three sun exposures.

A heater is a mounting job and a circuit. A 7,500 W unit is 31.3 A at 240V, 39 A at 125 percent, so a 40 A, 240V breaker and 8 AWG copper (NEC Table 310.16, 60 C column). The InoKraft's plug fits a 14-50 receptacle such as the Leviton 1450R. A licensed electrician should confirm all of it.

A DIY mini-split is a different kind of job. The indoor head hangs high on an exterior wall, a line set and a drain run through a hole in the wall to the outdoor unit, and the outdoor unit sits on a pad or a bracket with a power connection. The Fast-Fit set in the Albott title is a pre-charged line set with quick connections, which is the feature that makes a DIY install possible without refrigerant tools. The electrical side still needs care: read the listing for the circuit and the disconnect. The sizing sheets and the workshop amps calculator help you add it to the shop's load.

Where the head hangs matters in a woodshop. Put it away from the table saw and the sander, and keep the filter clean. A coil coated with fine dust loses capacity and smells. In an auto or fab shop, keep the head away from the welder and the grinder, where metal dust can reach the coil.

Both options keep the floor clear, which is the thing to want in a bay that parks a car. The head of a mini-split sits high on a wall, and the condenser is outside. A ceiling heater hangs above the bay. In a one-car garage the heater should not be above the car's roof or its open hatch, and the mini-split head should not blow directly on the car's paint or on a finish drying on the bench. The 12 x 22 ft woodshop layout and the 22 x 22 ft mixed layout show where the walls are free.

The mini-split's indoor unit does something a heater cannot: it moves air gently and quietly. A fan-forced ceiling heater makes a bit of noise, and it blows hot air from a high position, which warms the ceiling more than the bench. A heat pump head at the same height has the same problem, and a ceiling fan or the unit's own louvers help move the warm air down.

We do not type prices, so use the budget tiers in the table for the purchase and your own electricity rate for the running cost. The reasoning goes like this. The mini-split costs more to buy and a good deal more to install, even as a DIY job. The heater costs less to buy and almost nothing to install beyond the circuit. The mini-split uses less electricity for the same heat. If you run the shop 200 hours a winter, the heater is cheaper over any sensible horizon; if you run it 1,000 hours and want summer cooling and dehumidifying, the mini-split wins.

If you are on the fence, there is a middle path. Buy the heater now, insulate the door, and add the mini-split later when the shop earns it. The mini-split's circuit and wall hole are the long-lead items, so if you plan to add one, run the circuit and leave the wall plate in place during any other electrical work. The garage heater roundup covers the electric and gas tiers.

Mini-split for a shop you use all year in a climate with hot summers or damp air; electric heater for winter weekends, a rental, or a dusty bay. The mini-split solves rust and summer heat in one machine and costs more to buy and install. The heater is cheaper, simpler and heats only. Whichever you choose, insulate the door first. For the gas alternative see electric against propane.