What a Tauranga outdoor unit lives with
Sea spray zones
Within 500 m of the coast, harbour included, or 100 m of a tidal estuary, BRANZ's summary of NZS 3604:2011 puts a house in exposure zone D, a high risk of wind-blown salt. Breaking surf beach fronts get zone E, severe marine, under E2/AS1.
Industrial air
BRANZ's corrosivity study of the region found sulphur dioxide in the Mount Maunganui industrial area, around its Hewletts Road test site, higher than elsewhere in the Bay of Plenty.
Two seasons of use
NIWA gives Tauranga Aero AWS 176 cooling degree-days a year on top of 1,324 for heating, so the same unit may cool the lounge in February and heat it in July.
Why salt changes the service
Salt settles on the outdoor coil's fins and on any bare metal. Mitsubishi Electric NZ says servicing removes salt, dust and contaminants from coils and drain trays, and that living near the coast doesn't mean you'll automatically have problems, but extra care is important.
The warranty is the other reason to keep at it. Rinnai NZ makes the owner responsible for extra protection in corrosive settings such as sea air and industrial pollution. Mitsubishi Electric NZ lists keeping up any applied corrosion protection as an owner job. Black Diamond Technologies, its warranty company, covers corrosion damage only where its own approved Nyalic protection was applied and maintained, not protection added by someone else.
What a coastal service should cover
- The outdoor coil and fins cleaned of salt and grime, as well as the indoor filters.
- Paintwork and casing checked, and damage touched up. Temperzone's yearly list for Hitachi systems includes it.
- Any corrosion protection coating inspected and renewed if the brand's terms call for it.
- Brackets, bolts and the mounting pad checked for rust.
- The drain tray and drain line cleared.
- A dated written record you can keep with the warranty papers.
What makes it a bigger or smaller job here
Distance from the water is the big one. A unit on a beach front in zone E faces more salt than one a few streets back, so expect more coil cleaning and corrosion work the closer you are. A unit that was given extra coatings at install, as BRANZ recommends for coastal areas, is a maintenance job; a bare one may already need repairs.
Timing matters less than in a frosty town, because Tauranga units can run in both seasons. Pick a quiet month either side of summer and winter, and book the same time each year.
Between visits
You can
- Every 6 months, clear plants and rubbish from around the outdoor unit and, with it switched off, wash it down. Mitsubishi Electric NZ suggests car wash liquid, not dishwashing liquid, then a hose down.
- Clean the indoor filters as your manual says.
- Look for rust spots or bubbling paint on the casing, and tell the technician.
Leave to a licensed installer
- Cleaning the coil behind the covers.
- Corrosion treatment and paint touch-ups.
- Finding and fixing refrigerant leaks.
- Any electrical work.
Questions for a Tauranga service technician
- What corrosion protection does my unit have, and is it the kind my brand's warranty accepts?
- Will you clean the outdoor coil, not just the filters?
- Is anything already rusting that needs attention now?
- How often would you service a unit in my spot?
What we'd do
How we'd play it
Within 500 m of the water or near the Mount's industrial area, we'd service at least yearly and ask the technician whether our spot justifies more often. We'd keep every service record, because a corrosion claim lives or dies on them. Between visits, the 6-monthly wash-down is yours to do, and on the coast it's worth the half hour.