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A heat pump is a big enough purchase that you want it to last, and a quiet enough appliance that it is easy to ignore until the day it stops keeping the house warm. Somewhere between buying it and that day is a question worth answering early: how long should it actually last, and how do you know when it is nearing the end rather than just needing a small fix? Getting that call right saves you from both throwing good money at a dying unit and replacing one that had years left in it.
A heat pump typically lasts 10 to 15 years, and a well-maintained one can reach 20. The signs it is time to replace rather than repair include rising power bills, frequent breakdowns, uneven heating, strange noises, and needing a major part like the compressor on an older unit. A useful guide is the 50 percent rule: if a repair costs more than half the price of a new system and the unit is over 10 years old, replacement usually makes more sense.
Here is how long to expect from a heat pump, and the honest signs that it is time to replace yours.
Most heat pumps last around 10 to 15 years, and a well-installed, well-maintained unit can reach 20. Air-source heat pumps, the wall-mounted units in most homes, sit at the shorter end of that range, because unlike a system that only heats or only cools, a heat pump works year-round in both modes, so it simply racks up more running hours.
Three things move a unit toward the longer or shorter end of that range. Installation quality comes first, because a poorly installed or wrongly sized unit wears out years early. Maintenance is second, since regular servicing and filter cleaning genuinely add years. And usage and climate are third, though Auckland’s mild conditions are kind to a heat pump compared with harsher climates. Look after it, and the upper end of that range is realistic.
A heat pump rarely dies overnight. It tells you it is fading, if you know the signs.
| Sign | What it means |
| Rising power bills | The unit is working harder to do the same job as its efficiency drops |
| Frequent breakdowns | One repair a year is normal, but two or three in a season points to a unit in decline |
| Uneven or weak heating | Rooms that used to warm up easily no longer do, a sign of lost capacity |
| Strange noises | Grinding, rattling or banging suggests internal mechanical wear |
| A major part fails | Needing a compressor or similar on an older unit is often the tipping point |
| It is simply old | Past 10 to 15 years, the odds of costly failures climb |
None of these on its own means replace immediately, but two or three together on an ageing unit is the pattern that says the end is near.
When you are staring at a repair quote and wondering whether to spend it, professionals use a simple guideline called the 50 percent rule. If a single repair costs more than half the price of a new system, and the unit is more than about 10 years old, replacement is usually the smarter financial choice. The logic is that pouring a large repair bill into an old, less efficient unit rarely pays off, because you are likely to face the next failure before long, and the old unit keeps costing more to run in the meantime. For a unit well past its expected life, that threshold drops even lower, since the remaining runway is short.
Even when an ageing heat pump is still limping along, it is costing you in a way that does not show up as a repair bill. Efficiency fades as components wear, coils foul and refrigerant charge drifts, so the unit draws more power to deliver the same warmth, which feeds straight into your running costs. A modern high-efficiency inverter unit is dramatically more efficient than one from 10 or 15 years ago, and replacing an old unit can cut heating and cooling energy use meaningfully. There is also the refrigerant factor: older units may run on refrigerants that are being phased down, which makes repairs increasingly expensive and harder to source, while modern units use more efficient refrigerant such as R32. Add it up and the cheapest-looking option, keeping the old unit going, is often quietly the most expensive.
Knowing where a heat pump tends to wear helps you read the signs. The outdoor unit takes the hardest life, exposed to weather year-round, so its fan motor and compressor are common failure points, and the compressor is the big one, because it is the heart of the system and an expensive part to replace on an old unit. Capacitors and contactors, the smaller electrical components, tend to wear in clusters as a unit ages, which is why one repair often leads to another soon after. Coils foul and corrode over the years, and refrigerant charge can slowly drift. Indoor components generally outlast the outdoor unit. When a major outdoor part like the compressor goes on a unit past 10 years, that is usually the moment the 50 percent rule tips toward replacement.
The good news is that most of what shortens a heat pump’s life is preventable. Clean the filters regularly, roughly monthly in heavy use, so the unit is never starved of airflow. Book a professional service periodically to clean the coils and internals, check the refrigerant, and catch small issues before they become big ones. Run the unit sensibly rather than flat out. And make sure it was correctly sized and installed in the first place, since that sets the ceiling on how long it can last. These habits are the difference between a unit that quits at 10 years and one that is still going strong at 18.
If your unit has reached the end, replacing it is a chance to get a more efficient, better-suited system, not just a like-for-like swap. It is worth comparing the best heat pump brands and choosing a modern inverter model matched to your room. It is also worth checking whether you qualify for any support, since our guide to heat pump grants in NZ covers the funding that can bring the cost of a replacement down for eligible households.
The repair-or-replace call is easier with someone who can look at the actual unit, its age, its running cost and the repair on the table, and give you a straight answer rather than a sales pitch. That is exactly the advice worth having before you spend.
Varcoe has installed and serviced heat pumps across Auckland since 1975, more than 20,000 of them, so we have seen exactly how these units age and when they are worth keeping. For an honest assessment of your heat pump, get in touch, call us on 0800 088 888, or email info@varcoe.co.nz, and we will tell you whether to nurse it along or replace it.
Most heat pumps last around 10 to 15 years, and a well-installed, well-maintained unit can reach 20. Air-source units sit at the shorter end because they run year-round in both heating and cooling, clocking up more hours than a heat-only or cool-only system.
When the unit is over 10 years old and a repair costs more than half the price of a new system, replacement usually makes more sense. Frequent breakdowns, rising bills, uneven heating and a failed major component on an older unit all point the same way.
It is a guideline that says if a single repair costs more than 50 percent of the price of a new system, and the unit is more than about 10 years old, you are better off replacing it. Repairing an old, inefficient unit rarely pays off over the long run.
Yes. As components wear, coils foul and refrigerant drifts, the unit uses more power to deliver the same warmth, so your bills creep up. This is why an old unit can quietly cost more to run even when it is still working.
Clean the filters monthly in heavy use, book a professional service periodically, run it at sensible temperatures, and make sure it was correctly sized and installed. Good maintenance is the single biggest factor in reaching the upper end of a heat pump's lifespan.
Often, yes. A modern inverter unit is far more efficient than a 10 to 15-year-old model, so a replacement can noticeably cut running costs, avoids the rising repair bills of an ageing unit, and sidesteps the cost of older phased-down refrigerants.
We will look at your unit's age, running cost and the repair on the table, and give you a straight answer.
