How much does an oil column heater cost to run per hour in NZ?

About 0.87 an hour at full output, on a 2400W model at the national average variable rate of 36.3c/kWh. That is the figure to hold in your head - multiply it by the hours you actually run the heater. Models with a thermostat cycle on and off once the room is warm, so a full evening might average 60-70% of that.

Are oil column heaters cheap to run?

No, and the widespread belief that they are comes from a real fact being misapplied. They are 100% efficient - every unit of electricity becomes a unit of heat, nothing is wasted. But 100% is the ceiling for any resistive heater, and a heat pump beats it by moving heat rather than making it. So an oil heater is efficient in the narrow sense and expensive in the sense that shows up on your bill.

Is an oil column heater cheaper than a fan heater?

To run, only marginally - and only because column heaters are often lower wattage and have better thermostats. Watt for watt they cost exactly the same, because both convert electricity to heat at the same 1:1 ratio. What differs is comfort: an oil column holds heat and releases it slowly and quietly, which suits a room you occupy for hours, while a fan heater delivers a fast blast that suits ten minutes in a cold bathroom.

When does an oil column heater make sense?

When you need heat in a room that has no heat pump and putting one in is not practical - a spare bedroom, a sleepout, a rental where you cannot alter the building. It is also the right answer for genuinely occasional use, because the payback on a $3,000 install never arrives if you only heat the room a few nights a year. The problem is not owning one, it is using it as a main heat source all winter.

Running cost

What an oil column heater costs to run in NZ

By Jason Webb· Published 6 August 2026· Updated 6 August 2026· 7 min read

An oil column heater is one of the few appliances people buy because they think it is cheap to run, and that belief has a real fact underneath it. A column heater is 100% efficient. Every unit of electricity it draws becomes a unit of heat in your room, with nothing lost up a flue or out a vent.

The trouble is that 100% is not a good score here. It is the maximum any resistive heater can achieve, and a heat pump routinely beats it by two and a half times or more - because a heat pump does not make heat, it moves it. That gap is the entire story of this page.

Start with the cost of one hour

A typical column heater draws 2,400W at full output. At 36.3c/kWh that is $0.87 an hour, which is the only number you really need - everything below is that figure multiplied by how long the heater is on.

Monthly and per-winter cost by hours run per day, every day
Hours per day	Per month	Across a 3-month winter
1 hour	$27	$80
2 hours	$53	$159
4 hours	$106	$318
6 hours	$159	$477
8 hours	$212	$636
12 hours	$318	$954

Two caveats worth applying to that table. If your heater has a working thermostat it will cycle off once the room reaches temperature, so a four-hour evening might only draw full power for two and a half of them - knock 30-40% off. And if the heater is in a poorly insulated room it will cycle far less, because the room never quite gets there, which is how people end up at the bottom of that table without realising it.

The same heat, from a heat pump

The fair comparison is not "heater versus heat pump" in the abstract, it is: what does it cost to put 2.4 kW of heat into this room? A heat pump's rated figure is heat output, so a 2.4 kW unit delivers the same warmth as this heater.

The difference is what it draws to do it. On a real New Zealand winter morning a split system runs at a coefficient of performance around 2.6 - not the 3.8 on the box, which is measured in far milder conditions. Even derated like that:

Oil column heater: $0.87 per hour, drawing the full 2,400W.
Heat pump, same heat out: $0.34 per hour, drawing about 923W.

That is 62% less for identical warmth. Run four hours a day through winter and the gap is roughly $196 a season. Against a typical installed price of about $3,000 for a small split system, a heater used as a main heat source pays for its own replacement in a few winters - and keeps paying afterwards.

Our guide on what a heat pump actually costs to run works through the COP question properly, including why the showroom figure is not the one to plan around.

When a column heater is the right answer

None of the above means you should throw it out. There are situations where a plug-in heater is genuinely correct:

A room you cannot fit a heat pump to. A sleepout, a converted garage, a rental where you are not permitted to alter the building.
Genuinely occasional heating. A guest room used six nights a year will never pay back an install, no matter how good the hourly maths looks.
Backup during a cold snap, alongside a heat pump that is doing the main work.

A column heater also has real comfort advantages over a fan heater: it is silent, it does not blow dust around, and the oil holds warmth for a while after it switches off. Those matter in a bedroom. They just do not make it cheap.

Getting the cost down without replacing it

Heat the room you are in, and shut the door. A column heater is a room heater; leaving the door open turns it into a very expensive hallway heater.
Use the thermostat, not the power setting. Running at 1,200W with the thermostat wide open costs more over an evening than 2,400W with it set sensibly, because the second one switches off.
Deal with the draughts first. Sealing gaps and lining curtains reduces how long the heater runs, which is the only variable in the table above you actually control.
Do not use it to heat a bedroom overnight. An electric blanket costs a few dollars a year and heats the part that matters.

To run these figures against your own rate and your own hours, open the calculator. To see where this heater ranks against everything else in the house, the full appliance table puts it third out of 45.