Heat pump dryer vs vented dryer: NZ running cost
A vented (resistance) dryer uses about 3-4 kWh per cycle. A modern heat pump dryer uses roughly 1-1.4 kWh per cycle for the same load. Same dry clothes, a third the electricity. At Christchurch's 38.5 c/kWh that is the difference between paying $1.35 and 45 cents to dry one load.
Multiply by three loads a week through a four-month winter and that is around $37 vs $121, a saving of $84 over the wet season alone. A family doing eight loads a week saves more like $210 across a winter.
Why heat pump dryers use less
A vented dryer creates heat by passing electricity through a resistance element, exactly like a 2 kW oil column heater. Almost all of that heat ends up either drying clothes or blasting out the vent into your laundry/garage. It is brute force.
A heat pump dryer is a closed loop. A small refrigeration cycle moves heat into the drum to evaporate water, then condenses that water out of the air on a cold coil and drops it into a tank or down a drain. Because the same heat is reused, the unit uses 60-70% less electricity per kg of water removed. The drying air also runs cooler (around 50C vs 70C in a vented unit), which is gentler on clothes.
The cost breakdown
Assuming Christchurch's current 38.5 c/kWh:
- Vented dryer, 3.5 kWh/cycle, 3 cycles/week: 10.5 kWh/wk, about $18/month, $210/year.
- Heat pump dryer, 1.2 kWh/cycle, 3 cycles/week: 3.6 kWh/wk, about $6/month, $72/year.
- Vented dryer, 7 cycles/week (family of four): 24.5 kWh/wk, about $41/month.
- Heat pump dryer, 7 cycles/week: 8.4 kWh/wk, about $14/month.
The winter saving, region by region
The dryer earns its keep over winter, when the line outside is no use for weeks at a time. Take a family of four doing eight loads a week through a four-month wet season - roughly 17 weeks. The vented dryer at 3.5 kWh/cycle burns 8 × 3.5 = 28 kWh a week, or 476 kWh over the season. The heat pump dryer at 1.2 kWh/cycle uses 8 × 1.2 = 9.6 kWh a week, or 163 kWh - a saving of 313 kWh across the winter. What that 313 kWh is worth depends on your rate:
| Region | Rate | Vented winter | Heat pump winter | Saved |
|---|---|---|---|---|
| Wellington | 37.0c | $176 | $60 | $116 |
| Christchurch | 38.5c | $183 | $63 | $120 |
| Auckland | 41.2c | $196 | $67 | $129 |
| Balclutha | 52.5c | $250 | $86 | $164 |
Run the same household across a full year instead of one winter and the gap is wider still - comfortably $150-200 saved annually in most regions, and more in the high-rate southern lines areas like Balclutha and Dunedin. A Wellington couple doing one load a week saves far less, which is the honest case against rushing out to buy one.
The bigger hidden saving
A vented dryer dumps about 1.5-2 litres of water vapour per cycle into the air. If you vent into the laundry instead of outside (very common in NZ rentals and older homes), all that moisture stays in the house. You then run a dehumidifier or open windows to get rid of it, paying twice.
A heat pump dryer condenses that water and either drains it or holds it in a removable tank. None of it ends up on your walls or windows.
Does the payback actually stack up?
The honest answer depends entirely on how much you dry. A heat pump dryer costs $700-1,300 more than a basic vented unit up front, and it only recovers that through running-cost savings. For the family of four saving roughly $120-160 a winter (more across a full year), the premium is paid back in about four to six years - comfortably inside the machine's life. Run the sums forward and a busy household is well ahead of where the vented dryer would have left them.
For a couple doing one load a week, the maths flips. At 52 loads a year the heat pump saves only about 120 kWh - perhaps $50 a year - so a $900 premium takes the better part of two decades to recover. In that case the right move is usually to keep drying on the line, use whatever dryer you already own for the wet weeks, and not spend the money. Matching the machine to your actual load count is the whole decision.
The downsides
- Cycle time: heat pump dryers typically take 30-50 minutes longer per load. You are running a smaller, more efficient process for longer.
- Up-front cost: a decent heat pump dryer is $1,200-2,000, versus $400-700 for a basic vented unit. Payback is 4-6 years for a family doing several loads a week, longer for a couple.
- Maintenance: lint filters and condenser coils both need cleaning. A clogged condenser will murder the unit's efficiency.
- Cold rooms: heat pump dryers struggle below about 5C. If your laundry is an unheated outhouse in Otago, the cycle time stretches further.
What about a clothes line?
Free, obviously. The challenge in NZ is that for four months of the year you cannot reliably dry outside, and indoor drying without a dryer is the single biggest source of indoor dampness. See the damp homes article for what that costs to deal with.
The right NZ winter setup for most households is: line dry whenever you can, heat pump dryer for the days you can't, never indoor rack-dry without simultaneous dehumidification.
What to do next
You do not have to replace a working vented dryer to start saving - habits matter as much as hardware:
- Spin harder first. A faster final spin on the washing machine wrings out more water, so the dryer - vented or heat pump - has less to do and runs a shorter cycle. It is the cheapest efficiency gain in the laundry.
- Dry full loads. Two half-loads cost almost double a single full one. Batch the drying.
- Vent a vented dryer outside. If you are keeping the old machine, at least duct it through a wall so the moisture leaves the house rather than soaking into it.
- When it dies, replace with a heat pump model if your household does three or more loads a week - that is where the four-to-six-year payback holds up. Model both options in the heat pump dryer and vented dryer calculators with your own cycle count first.
Compare your own laundry costs in the NZ Power Bill Calculator: both dryer types are in there as cycles-per-week appliances.
Related guides
- Dehumidifier or heat pump for a damp NZ home? - indoor drying without ventilation is the main moisture source in NZ homes
- Average NZ power bill by region (2026) - put your laundry cost in the context of a full household bill
- The most expensive appliances in NZ homes - where the dryer ranks against heating and hot water