Whakatāne's climate and coast
Frequent winter frosts
Whakatane Aero averages 50.8 ground frosts and 19.0 air frosts a year, including 7.6 air frosts in July alone (NIWA).
More heating than Tauranga
NIWA's degree-day table gives Whakatane Aero AWS 1586 heating degree-days a year against Tauranga's 1324, and 142 cooling degree-days. Wikipedia's table of NIWA's 1991 to 2020 normals puts the February mean high at 24.5 degrees.
Humid in winter
Mean 9 am relative humidity at Whakatane Aero AWS is 83% over the year and 90% in June.
Salt further inland
BRANZ Study Report SR458 recommends widening the NZS 3604 exposure zone C boundary slightly inland from Te Puke to Whakatāne, based on measured corrosion and the prevailing northwesterly and southwesterly winds.
Geothermal air nearby
SR458 also recommends moving Kawerau, Te Teko and Edgecumbe from zone B to zone C, citing geothermal sources, industry and higher hydrogen sulphide or sulphur dioxide levels.
Damp and mould above average
In 2023, 21.0% of Whakatāne homes were always or sometimes damp, and 4.4% always had mould bigger than an A4 sheet, against 3.5% nationally. 32.5% used a wood burner as a main heater.
What that means for your heat pump
Size for the frosty mornings. Compare the label's 2 degree heating figure with the 7 degree one. EECA says some heat pumps deliver more heat at 2 degrees and some deliver less. The size calculator is a good place to start on the room.
Protect the outdoor unit. Near the coast, and in Edgecumbe or Te Teko, ask what corrosion protection is included. BRANZ says to specify extra anti-corrosive coatings in coastal and geothermal areas, and Haier's warranty booklet excludes defects from salt and geothermal sulphur environments.
Use the sunshine. BRANZ says heat pumps heat best with the outdoor unit in the warmest spot, such as a north or west facing wall.
Don't leave the damp to the heat pump. Warm rooms help, but moist air still needs to get out. Extractor fans that vent outside and home ventilation are the next step.
When you're ready, tell us about the room. Installers who specialise in this kind of job see it. Should nobody near Whakatāne take it within 48 hours, heat pump installers elsewhere in the Bay of Plenty may see it.
What we'd do
Where we'd start in Whakatāne
We'd pick a heat pump that holds its output at 2 degrees, put the outdoor unit on a sunny wall, and get corrosion protection on the quote if the house is near the coast or in the geothermal country inland. Then we'd keep up servicing, because Mitsubishi Electric NZ says coastal and geothermal systems may need it more often than the yearly minimum.