This question is a little bit like 'how long is a piece of string', however it is useful to know something about the expected service life of a heat pump and what affects it.
Note this is not a guarantee of how long your heat pump WILL last it is an examination of the available information on how long heat pumps tend to last as a group.
#1 Some typical heat pump appliances and how long they last:
A typical expected lifespan of an AC unit is 15 years, the author knows of units that have operated for over 17 years but there are also units that die after 7 years.
Refrigerators (modern ones) also tend to last 15 years however some of the older less efficient models are known to last 40 or 50 years plus; probably due to heavier duty components that would be considered overkill in modern appliances.
Hot water heat pumps (HWHP):
Hot water heat pumps are not (currently) as widely used as the first two appliances; however their popularity is growing fast.
As such there tends to be less information out there on the longevity of HWHP and what data there is may be skewed by initial, poor quality HWHP offerings.
However a good quality hot water heat pump, like the Sanden HWHP, has a design life of 15 years and could last 15 years + with proper care; which would line up with the expected life span of other heat pump appliances.
#2 What are the main factors that affect the longevity of your heat pump?
Whether or not your heat pump makes its expected lifespan or exceeds it will depend on a number of factors, with the three most important ones being outlined below:
You get what you pay for; a cheaper unit will use cheaper components that are not designed to last. Or it will be manufactured with looser quality control affecting overall integration of components.
Cheaper units also tend to have worse after sales support. It is worth asking yourself the question, is a cheaper unit really cheaper when a better quality unit might last twice as long despite being less than twice the cost of the budget option?
Better quality options also tend to be more efficient saving you money on running costs.
The harder the life of the heat pump the quicker you can expect it to wear out. Things like ambient temperature can affect how hard a heat pump has to work if it operates in a very cold environment (near its minimum working temperature) it will need to work harder and wear out quicker.
You have no control over the ambient air temperature (although you can shelter your HP unit in some situations by installing it in an enclosure) but you do have control over how you operate your heat pump i.e. how you configure the settings.
For example if you set your AC to 18 C then turn it off multiple times on a hot day (rather than just setting it to 24 C and giving it time to work) it will wear out quicker as the unit struggles to reach your high set-points (or lower temperature set-point when cooling).
Steady consistent operation is the best for any appliance and increases its expected lifespan.
The final factor in how long your heat pump lasts is how well it is maintained. A well maintained appliance can often exceed its design life significantly. Some simple maintenance tips include:
✅ Make sure you check your outdoor HP during winter to make sure ice isn't building up on the coils.
✅ Clean the air filter on your AC units regularly it is worth inspecting them once a month or so after a season of heavy use. Or use the automatic cleaning function if your AC unit has it.
✅ Make sure the cooling fin (i.e. heat exchanger) on your heat pump is clean before a heavy use season.
✅ Keep weeds and other plants at least 30 cms from your heat pump unit; so debris does not fall into the unit.
✅ Make sure to remove any air from the lines of your hot water heat pump every by:
+ Pulling the PTR lever every 5 months (consult your manual for details)
+ Open the water drain plugs every 12 months until there is no air and the water is clear.
It is worth having your AC heat pump looked at by a professional if you notice any of the following:
✅ Unit is blowing hot or cold air which is inconsistent to temperature settings
✅ Your unit has diminished air flow
✅ It’s emitting strange noises or strange smells
✅ Your unit is leaking or producing excess moisture
✅ Your unit is short cycling
✅ Your energy bills have dramatically increased
✅ Your unit requires frequent repairs (and is out of warranty)
In summary if you buy a quality heat pump, keep it well maintained and operate it is a steady manner there is every reason you should expect to get 15 years + life out of it, and save a tonne of energy and money in the process.