Heat-pump hot water vs gas: costs, comfort, carbon

26 July 2025

Gas used to be the default for many Kiwi homes. Bottled LPG, califonts on the wall, or piped reticulated gas in the cities. But with rising costs and climate goals, the balance has shifted.

Here’s how gas stacks up against modern hot-water heat pumps.

Quick comparison

Factor	Heat-pump hot water	Bottled gas	Gas califont	Piped gas
Running cost	~60–75% less than electric	Higher, plus delivery fees	High in winter	Adds daily fixed charges
Fixed charges	None	Bottle rental	None	$1–$2/day
Safety	No combustion	Flammable	Flammable	Flammable
Carbon	Low	High	High	High

Bills in the real world

On paper, gas sometimes looks cheap per unit. But add daily line charges or bottle fees, and many households find bills higher than expected.

Heat-pump hot water has no daily charges. Every kWh of electricity does more work, thanks to COP ratings of 3 or more. That’s why many households switching from gas see their annual bills drop.

Comfort and reliability

Heat pumps deliver steady hot water to a cylinder. No cold bursts when someone else turns a tap.

Califonts can struggle with flow rates, especially when multiple taps run. Bottled gas can run out mid-shower. Heat pumps just quietly refill your tank.

Carbon counts

Gas is fossil fuel. Heat pumps, powered by NZ’s mostly renewable grid, slash emissions. For a family, the shift can cut tonnes of CO₂ a year.

Solar advantage

Add solar PV and the savings grow. Heat-pump water heaters store free solar energy in the tank, ready for evening use. It’s often cheaper and simpler than buying a battery.

Safety and peace of mind

Gas systems bring combustion, leaks, and venting requirements. Heat pumps don’t burn fuel. Just clean electricity and safe, sealed refrigerant loops.

The bottom line

For most households, heat-pump hot water wins on bills, comfort, and carbon.

👉 See if Emerald or Primsal fits your home.