Radiant vs Convection Heaters: What's the Real Difference, and Is Either Worth It in Adelaide?

"Radiant or convection" is usually the wrong question to be asking first. Both are legitimate, common types of portable electric heater, and the type itself has almost no bearing on your power bill or your household's safety — those come down to wattage, how the heater's actually used, and what it's plugged into. This article covers the real difference properly, then the two parts that matter more in practice: running cost and electrical safety.

We're Voltas Electrical & Airconditioning, a licensed Adelaide electrical and air conditioning team (licences BLD 274739, PGE 265145, AU 61210) — which means we see this question from both sides: the electrical safety of how a heater's wired in and used, and the heating-efficiency comparison against reverse-cycle air conditioning, which is the option most portable-heater buying guides don't mention at all.

Radiant vs Convection: The Actual Difference

Radiant heaters — bar heaters and radiant panel heaters are the common types — work by emitting infrared radiation that heats whatever's directly in its path: your body, the couch, the wall behind you. They warm up almost instantly and are effective the moment you switch them on, but they don't do much for the air temperature of the room as a whole — step out of the direct line of the heat and you're back to feeling the room's actual temperature straight away.

Convection heaters — oil column heaters, fan heaters, and panel convectors all fall into this category — instead warm the air itself. Oil column heaters do this slowly via natural convection currents (warm air rises, cool air is drawn in to replace it); fan heaters force the same process with a built-in fan, warming a room faster but usually more noisily and unevenly. Either way, the whole room's air temperature climbs gradually rather than any one spot warming immediately.

Running Costs: Is One Actually Cheaper?

Here's the part most "radiant vs convection" comparisons get wrong by implying one type is inherently more efficient: both are resistive electric heaters, meaning they convert electricity to heat at a 1:1 ratio no matter which category they fall into. A 2,400W radiant bar heater and a 2,400W oil column heater cost exactly the same to run per hour — the type of heat they produce is different, but the electricity-to-heat conversion isn't. The real cost driver is wattage (typically 1,000W-2,400W for most portable heaters) multiplied by how many hours a day you run it, and South Australia's electricity prices — among the highest of any state under the Australian Energy Regulator's 2026-27 Default Market Offer — make that multiplication add up faster here than in most other parts of the country.

The Electrical Safety Side Most Guides Skip

This is the part that actually matters most, and it's rarely mentioned in a straight radiant-vs-convection comparison: portable heaters should never be plugged into a power board or extension cord. A typical bar or panel heater draws 2,000W or more on its own — a genuinely large load for a single appliance — and most power boards and extension leads simply aren't rated to carry that safely on a continuous basis. Fire authorities attribute a large share of portable heater house fires directly to this exact habit. The rule is simple: plug a heater straight into a wall socket, every time, and if the nearest socket is inconveniently placed, that's a sign to get an extra power point installed properly rather than reaching for an extension cord as a permanent fix.

The other thing worth checking is what else is already running on the same circuit. If a heater tripping your safety switch or breaker is a familiar problem, especially when it's on at the same time as another high-draw appliance like a kettle or a hair dryer, that's often a sign the circuit — or the switchboard behind it — is under-sized for what your household actually plugs in now versus when the house was wired. Our guide on when to upgrade your switchboard covers exactly this kind of warning sign in more depth, and if a full rewire is more the issue, our signs your home needs a full rewire guide is the next place to check.

Where Reverse-Cycle Air Conditioning Beats Both

If you're heating more than one room, or running a heater for hours at a time most winter evenings, it's worth knowing what the alternative actually costs. A modern reverse-cycle air conditioner has a coefficient of performance (COP) of roughly 3.5 to 5 in heating mode — meaning it delivers 3.5 to 5kW of actual heat for every 1kW of electricity it uses, because it moves existing heat rather than generating it from scratch the way a resistive heater does. A portable radiant or convection heater, by contrast, always sits at a COP of exactly 1. In practical terms, reverse-cycle heating typically costs around a quarter as much as a portable heater for the same amount of warmth, and covers a whole room — or with a ducted system, a whole home — rather than one spot near the heater.

None of this makes a portable heater pointless — for briefly taking the chill off a single room, a radiant or convection heater is still often the simpler, cheaper-upfront option. But if you're finding yourself running one for hours every night through winter, that's usually the point where reverse-cycle heating pays for itself faster than most people expect. Our installation team can talk you through the real numbers for your own home, and if you're also weighing up a ducted system for whole-home coverage, our complete guide to ducted air conditioning covers that side in full.

We see this question come up differently depending on the home. Older, established homes around Kensington often still rely on a portable heater or two in rooms an ageing ducted or gas system doesn't reach well, while newer builds in areas like Craigmore are more likely to already have zoned reverse-cycle ducted air conditioning covering the whole home from the outset — which is exactly why the "should I just get a heater or fix the heating properly" answer looks different from house to house.

Portable heater safety guidance cross-checked against Australian fire authority advice on power boards and extension cords; reverse-cycle heating efficiency figures cross-checked against published Australian coefficient-of-performance data; electricity pricing context per the Australian Energy Regulator's 2026-27 Default Market Offer. For a licensed check of your own circuits, see our electrical repair & fault finding page.