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Whanganui, Manawatū-Whanganui

Heat pumps in WhanganuiMild weather, damp houses.

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Whanganui has the mildest temperatures in its region, yet its homes are damper than the national average. More of them also lean on wood burners and portable gas heaters than most. A properly sized heat pump, with extractor fans or ventilation where needed, handles the heating and helps with the damp.

What Whanganui homes are working with

The region's mildest

NIWA says Whanganui has the least extreme temperatures of the Manawatū-Whanganui sites it compared: an average of 17 days a year above 25 degrees and only 2 below 0. On the 1991 to 2020 normals, via Wikipedia, July nights average a low of 5.8 degrees and February days a high of 23.0.

Less heating than inland

NIWA's Spriggens Park station logs 1,585 heating degree-days and 110 cooling degree-days a year, against 1,872 heating degree-days at Palmerston North. MBIE's H1/AS1 guidance puts Whanganui District in climate zone 2.

Damp homes

EHINZ found 24.1% of people in the Whanganui health district lived in a damp dwelling in 2023, well above the national 20.6%.

Portable gas heaters

EHINZ says portable unflued gas heaters release water vapour, nitrogen dioxide, carbon monoxide and other pollutants indoors. In 2023, 4.3% of dwellings in the Whanganui health district used one, the second-highest rate in the country, against 2.5% nationally.

Wood burners, and fewer heat pumps

45.1% of dwellings in the health district used a wood burner as a main heater in 2023, against 28.2% nationally, and 48.16% of Whanganui District homes used a heat pump.

Salt near Castlecliff

Homes within 500 m of the coast or 100 m of a tidal estuary, around Castlecliff or the river mouth for example, are in NZS 3604 exposure zone D for sea-spray salt.

A council-owned gas network

GasNet runs Whanganui's gas network and is owned through the district council's holding company. The council said in 2016 it had about 10,000 connections.

If you smell gas

WorkSafe's steps: keep flames and cigarettes away, and don't flick any electrical switch on or off, because a spark could ignite the gas. Don't use your mobile phone nearby. If it's safe, turn off the valves to the gas appliances and the supply at the meter or LPG cylinder, then open doors and windows. If the smell persists, go outside to a safe place, and dial 111 in an emergency.

Replacing a portable gas heater

If a portable gas heater is doing the heating, a fixed heater is the upgrade. BRANZ doesn't recommend any unflued gas heater, natural gas or LPG, for health and safety reasons, and unflued gas heaters can't count towards any part of the healthy homes heating standard for rentals.

BRANZ calls heat pumps the most efficient form of purchased space heating commonly available, so one in the main living area is a strong replacement. If you'd rather stay with gas, a flued gas heater on the GasNet network is work for a registered gasfitter, and the PGDB says homeowners can't install, alter or repair gas appliances themselves.

Other jobs that come up in Whanganui

A heat pump to take over from the wood burner, or share the work. With only 2 days a year below 0, the 7 degree heating figure is the main one to size on. Warmer Kiwi Homes, which EECA runs, stopped taking new wood burner applications on 9 January 2026. See heat pump installation.

Ventilation for damp. Once the house is properly heated and the extractor fans vent outside, a home ventilation system can move the remaining moisture out, and Consumer NZ says positive pressure suits older houses with wooden joinery.

Corrosion protection and servicing for outdoor units near Castlecliff and the river mouth.

Your part, and the trades' part

You can

  • Run the bathroom and kitchen extractor fans, and check they vent outside.
  • Note which rooms get condensation and mould first.
  • Keep the outdoor unit clear of plants and the woodpile.
  • Clean the heat pump filters as your manual says.

Leave to a licensed installer

  • Disconnecting or removing a fixed gas heater, which is gasfitting work.
  • Sizing and placing the heat pump.
  • Corrosion protection near the coast.
  • The electrical connection and the Certificate of Compliance.

What we'd do

Our take for Whanganui

If a portable gas heater is still in use, we'd make replacing it with a heat pump the first job, because that takes a source of indoor moisture and fumes out of the house. Then we'd give the house a winter with working extractor fans before deciding on ventilation. Near the coast, we'd want corrosion protection on the quote.

Questions people ask

Is a heat pump safer than a portable gas heater?
BRANZ doesn't recommend any unflued gas heater for health and safety reasons, and EHINZ says they release nitrogen dioxide and carbon monoxide indoors. A heat pump moves heat with electricity rather than burning anything in the room, and it can count towards the rental heating standard, which an unflued gas heater never can.
Does a Whanganui heat pump need to handle frost?
Rarely: NIWA counts only 2 days a year below 0 there. Size on the 7 degree heating figure, and check the 2 degree one if your spot gets colder nights than town.
Can I swap my gas heater for a heat pump myself?
A portable heater on a gas bottle you can simply stop using. Disconnecting a fixed gas heater is gasfitting work, and connecting a heat pump is prescribed electrical work for a registered electrician, who must give you a Certificate of Compliance within 20 days.
Can you find me an installer in Whanganui?
Send us your job and postcode, and registration-checked installers who specialise in it can see it. If nobody near Whanganui takes it within 48 hours, heat pump installers elsewhere in Manawatū-Whanganui may see it too.

Ready for the right installer to take a look in Whanganui?

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Read next

  1. 01Heat pumps in Manawatū-WhanganuiFrosty Palmerston North, damp Whanganui, burners, gas heaters and the rules across Manawatū-Whanganui.
  2. 02Heat pump installationWhich heat pump suits the room, how to size it, and what a good install and quote include.
  3. 03Gas heatingFlued gas heaters and gas fires, LPG or natural gas, who installs them, and the paperwork you should get.
  4. 04Home ventilation systemsWhat a home ventilation system does, the two main types, and how to tell which one suits your house.
  5. 05The healthy homes heating standardWhat the rental heating standard asks for, which heaters count, and how to check a heat pump against it.
  6. 06Heat pumps compared with other heatingHow a heat pump stacks up against a wood burner, gas, electric heaters and central heating.

Where this information comes from

We don't publish prices. Every home is different, so an installer's written quote is the only real number. How we write and check these pages.

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