- Filter cleaning
- Every 2 weeks to 3 months depends on brand and use
- Water temperature
- Lukewarm Mitsubishi: no hotter than 50°C
- Professional service, single unit
- $79–$249 typical per visit
Dirty filters are the most common reason a heat pump feels weaker than it used to. Dust blocks airflow, so the unit works harder to deliver the same warmth. Cleaning them is a ten-minute job that most owners can do themselves, and it is the one piece of maintenance manufacturers and EECA both tell you to keep on top of.
How often should you clean heat pump filters?
It depends on the brand and how hard the unit works. Daikin NZ recommends cleaning indoor filters every two weeks, and more often in dusty homes. Mitsubishi Electric's cleaning guide recommends at least every seasonal change. EECA's advice is every couple of weeks. A practical approach: check them monthly through winter and clean them whenever you can see a grey layer of dust.
| Source | Filter cleaning advice |
|---|---|
| Daikin NZ | Every two weeks; more often in dusty or polluted environments |
| Mitsubishi Electric NZ | At least every seasonal change; air cleaning filters replaced as the manual advises |
| EECA | Clean filters every couple of weeks using a vacuum or warm water |
Sources: Daikin NZ maintenance FAQ, Mitsubishi Electric NZ cleaning guide, EECA. Always follow your model's manual.
How do you clean heat pump filters step by step?
How to clean the filters in a high-wall heat pump
- Switch the unit off
Turn the heat pump off with the remote, then switch off power at the isolation switch (often on or near the outdoor unit) so the fan cannot start while your hands are inside.
- Lift the front panel
Stand on a stable step, not a chair. Lift the front panel from the bottom edge until it clicks into its open position.
- Remove the filters
Slide the mesh filters down and out. Some units also have separate air-cleaning filters clipped behind them. Avoid touching the metal fins behind the filters, which are sharp.
- Vacuum off the dust
Use a soft brush attachment on a low setting to lift dust off the filter from the dusty side.
- Wash if needed
If dust remains, rinse or soak the filters in lukewarm water with a little mild detergent. Do not use hot water (Mitsubishi says no hotter than 50°C), solvents or abrasive cleaners.
- Dry in the shade
Shake off water and let the filters dry completely out of direct sunlight, or pat dry with a soft cloth. Never refit a damp filter.
- Refit and close
Slide the filters back into place, lower the front panel until it clicks, restore power and run the unit to check it starts normally.
Where is the filter on my heat pump?
On a wall-mounted heat pump the filters sit directly behind the hinged front panel: lift the panel from its bottom edge and you will see one or two mesh screens across the top of the unit. Floor consoles, ceiling cassettes and ducted systems hide theirs in different places, set out below.
| Indoor unit | Where the filter is | How to get it out |
|---|---|---|
| High-wall (most NZ homes) | Behind the front panel, across the top of the unit | Lift the panel until it clicks open, then slide each mesh filter down and out |
| Floor console | Behind the front grille, low down | Open or unclip the front grille; filters lift or slide out from the front |
| Ceiling cassette | Behind the square centre (return air) grille | Release the grille catches, let it swing down, unclip the filter. Use a proper ladder |
| Ducted | Behind the return air grille, usually in a hallway ceiling, sometimes at the unit itself | Open the grille, pull the filter out of its frame. See the ducted section below |
Layouts vary by model; the operation manual for your unit shows its filter. Most makers publish manuals on their NZ sites.
Do heat pump filters need to be replaced?
Usually not. The main mesh filters in a wall or floor unit are washable and are meant to be cleaned and refitted, not thrown out; replace one only if it is torn, warped or the frame has cracked. The exception is the extra air-purifying filter some models carry: Daikin NZ says its Titanium Apatite filter should be cleaned every six months and replaced every three years, and Mitsubishi Electric says to replace its air-cleaning filters as the manual advises.
| Filter | Clean | Replace |
|---|---|---|
| Main mesh filter (all brands) | Every 2 weeks to every season (see above) | Only if damaged; order the model's part from the maker or your installer |
| Daikin Titanium Apatite air-purifying filter | Every 6 months: vacuum, soak 10–15 min in lukewarm water, dry in shade | Every 3 years (Daikin NZ) |
| Mitsubishi Electric air-cleaning filters | As the manual says | As the manual says (Mitsubishi Electric NZ) |
| Ducted return-air filter | As the system manual says | Some ducted filters are disposable media; check the manual or ask at the service |
Sources: Daikin NZ maintenance FAQ (read 3 Nov 2026), Mitsubishi Electric NZ cleaning guide.
What should you avoid when cleaning a heat pump?
- Spraying water or cleaner into the unit. Mitsubishi Electric warns never to apply water to the inner workings.
- Using benzene, thinners, polishing powders or insecticide on any part.
- Drying filters in direct sun or near a heater, which can warp them.
- Touching the heat exchanger fins with bare hands; they can cut.
- Standing on an unstable chair or bench to reach a high-wall unit.
- Buying coil-cleaning sprays for the indoor unit. Leave deep cleaning to a technician.
How do you look after the outdoor unit?
Keep the outdoor unit clear so air can flow through it. Pull away leaves, grass clippings and plants, and do not stack firewood, bins or covers against it. Daikin NZ advises keeping the exterior unit free of leaves and debris, especially before peak seasons. In frosty areas you may see steam or water around the unit on cold mornings; that is the normal defrost cycle, so leave it alone and keep the drain path clear.
When should you call a professional?
Filter cleaning is yours to do. Anything inside the casing is not. Daikin NZ recommends an annual inspection by a qualified technician before heavy seasonal use, and a service is worth booking sooner if you notice any of these:
- Weak airflow or poor heating even with clean filters.
- A musty or mouldy smell when the unit starts.
- Water dripping from the indoor unit.
- Ice building up on the outdoor unit that does not clear.
- Rattling, grinding or unusual noises.
- An error code flashing on the indoor unit.
A professional service typically costs $79–$249 per visit for a single wall or floor unit, more for multi-split and ducted systems. It usually includes cleaning the coil and fan, checking the drain, and testing the system. Specialist cleaners publish $109 to about $195 for a deep clean of the first unit; see heat pump cleaning cost NZ for six real prices, and heat pump servicing for what to expect and what to ask for. If the unit is old and failing, our heat pump replacement cost guide covers the options.
How do you clean filters on a ducted heat pump?
Ducted systems usually have one larger filter behind the return air grille, often in a hallway ceiling. The process is similar: switch off, open the grille, remove and vacuum or rinse the filter, dry it fully and refit. The filter may be above head height, so use a proper ladder or ask for the service technician to show you. Check your manual for how often your system needs it.
Frequently asked questions
How often should I clean my heat pump filter?
Daikin NZ suggests every two weeks and Mitsubishi Electric at least every seasonal change. In winter, when the unit runs most, checking monthly and cleaning when you see dust is a sensible routine.
Where is the filter on my heat pump?
On a wall-mounted heat pump it is behind the hinged front panel: lift the panel until it clicks and slide the mesh filters down and out. Floor consoles have it behind the front grille, ceiling cassettes behind the centre grille, and ducted systems behind the return air grille, usually in a hallway ceiling.
Do heat pump filters need to be replaced?
The main mesh filters are washable and only need replacing if they are damaged. Extra air-purifying filters are different: Daikin NZ says to clean its Titanium Apatite filter every six months and replace it every three years.
Can I wash heat pump filters in water?
Yes. Vacuum first, then rinse or soak in lukewarm water with a little mild detergent if needed. Dry them fully in the shade before refitting.
Can I put heat pump filters in the dishwasher?
Manufacturers recommend a vacuum and lukewarm water, and warn against hot water and harsh cleaners. A dishwasher's heat and detergent can damage filters, so stick to hand washing.
Does cleaning the filter save power?
Clean filters let air flow freely, so the unit does not have to work as hard. Daikin NZ says a clean filter can cut energy use by 5–15% compared with a blocked one.
How much does a heat pump service cost in NZ?
Typically $79 to $249 per visit for a single wall or floor unit in 2026, with multi-split and ducted systems costing more.
Why does my heat pump smell musty?
Dust and moisture can build up on the coil and fan inside the unit. Clean the filters first; if the smell continues, book a professional service to clean the internal parts.
Is steam from my outdoor unit normal?
Yes, on cold mornings. The unit periodically defrosts its coil, which can produce steam and water. Keep the area around it clear so it drains.