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 36.6 c/kWh that is the difference between paying $1.10 and 40 cents to dry one load.
Multiply by three loads a week through a four-month winter and that is around $35 vs $115, a saving of $80 over the wet season alone. A family doing eight loads a week saves more like $200 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 36.6 c/kWh:
- Vented dryer, 3.5 kWh/cycle, 3 cycles/week: 10.5 kWh/wk, about $17/month, $200/year.
- Heat pump dryer, 1.2 kWh/cycle, 3 cycles/week: 3.6 kWh/wk, about $6/month, $70/year.
- Vented dryer, 7 cycles/week (family of four): 24.5 kWh/wk, about $39/month.
- Heat pump dryer, 7 cycles/week: 8.4 kWh/wk, about $13/month.
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 rather than 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.
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 quietly 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.
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