Running cost
How much does electric underfloor heating cost to run?
Electric underfloor heating costs about $16–$26 a month to run for a bathroom on a timer — roughly $5 a week. That is for a floor switched on for a few hours a day around the times the room is used, which is how we set them up and how nearly every Auckland home runs them.
This is an estimate, not a fixed price. What your own floor costs to run depends on the size of the room, how long you have it switched on each day, how well the room holds heat, and what you pay for power. A small ensuite on a short timer sits at the bottom of that range or below it; a larger floor left on for much of the day costs considerably more.
Why the timer is the whole story
Almost everything written about underfloor heating being expensive comes from floors left running all day. A heated floor only costs what it costs while the cable is actually drawing power, and with a schedule that is a short window each morning and evening rather than the whole day. Set the thermostat to bring the floor up before you get up and again before the evening, and the bill stays where the figure above sits. Leave it running around the clock and it climbs several times over.
Every install we do comes with a programmable thermostat for exactly this reason. It is not an extra: it is the part that keeps the running cost sensible, and we set the first schedule with you before we leave the job.
The floor is warm for longer than the cable is on
A sensor sits in the floor alongside the heating cable. Once the floor reaches the temperature you have set, the sensor cuts the cable, and from then on it only switches back on in short bursts to hold that temperature. Tile and stone also hold heat well, so the floor stays comfortable for a good while after the cable stops altogether. In practice the heating draws power for a fraction of the time the floor actually feels warm, which is why the real bill usually comes in below what people expect.
What changes your running cost
The size of the room. Running cost follows floor area. A small ensuite costs noticeably less to run than a heated kitchen or living area for the same number of hours, simply because there is more floor to warm.
How long you run it. This is the biggest lever you control. Two hours a day and eight hours a day are different bills on the same floor.
How well the room holds heat. Single glazing, an uninsulated wall or a cold slab underneath all mean the thermostat calls for heat more often. A well-insulated bathroom is cheap to keep warm; a draughty one is not.
What you pay for power. Power prices differ between retailers and plans. Some plans charge less at night or early morning, which suits a floor scheduled to come on before the house wakes up.
The floor covering. Tile and stone pass heat up efficiently. Timber, vinyl and carpet insulate the floor to some degree, so the heating works a little harder to reach the same comfort underfoot.
How it compares with heating the room another way
A bathroom floor on a timer costs roughly what a heated towel rail costs to leave on, and less than a plug-in fan heater running the same hours. The difference is what you get for it: a wall heater warms the air and stops the moment you switch it off, while a heated floor warms the surface you are standing on and keeps doing so for a while afterwards. There is also nothing on the wall, no fan noise and no vents.
Against a heat pump across a whole house, underfloor heating is not the cheaper way to heat every room — and we would not tell you it is. Where it wins is the rooms a heat pump handles badly or cannot reach: bathrooms, ensuites and tiled entries, where the complaint was never the air temperature but the cold floor.
Keeping the cost down
- Use the schedule, not the switch. Set it and leave it. Manual switching on and off is how floors end up running longer than anyone intended.
- Heat the rooms you stand in barefoot. Bathrooms, ensuites, kitchens and tiled entries earn their running cost. A bedroom usually does not.
- Set it to comfortable, not hot. A floor only has to be warmer than your feet to feel warm. Winding the thermostat up costs money and does not make the room nicer.
- Fix the draughts first. An extractor fan left running or a gap under a door will cost you more than the heating ever saves.
Common questions about running cost
How much does electric underfloor heating cost to run?+
About $16–$26 a month for a bathroom run on a timer for a few hours a day — roughly $5 a week. It is an estimate, not a fixed price: the cost moves with the size of the room, how long you run it and what you pay for power.
Is underfloor heating expensive to run?+
Not on a timer. The reputation comes from floors left running constantly, which costs several times more. Set to come on for a few hours around the times you use the room, a bathroom floor costs about the same as running a heated towel rail.
Does it cost more in a bigger room?+
Yes. Running cost follows floor area, so a heated kitchen or living area costs more to run than a small ensuite for the same hours. That is one reason we talk through how you will actually use each room before quoting it.
Does the floor draw power the whole time it is switched on?+
No. A sensor in the floor cuts the cable once the floor reaches the temperature you set, then switches it back on in short bursts to hold it there. The floor is warm far longer than the cable is drawing power.
Is it cheaper to leave it on low all day?+
No. That is the single most expensive way to run it, and it is the mistake behind most complaints about underfloor heating being costly. A tiled floor holds heat well, so a timed burst before you need the room beats running it all day.
Will it heat the whole room or just the floor?+
In a small, well-insulated bathroom it is usually all the heating needed. In a large open living area treat it as comfort underfoot rather than the only heat source — which also keeps its running cost sensible.
What it costs to install
Running cost is one half of the question. Installed prices for Auckland rooms are on the cost page.