Should I Switch from Gas Hot Water?
The short answer: almost certainly yes. Here's the full picture: costs, savings, the disconnection process, and which heat pump systems work best for gas switchers.
By Carolyn Cox · Sustainability Expert, 25+ years · Updated August 2026
The money case — why gas hot water no longer makes sense
Gas used to be cheaper than electricity for heating water. That's no longer true. Significant gas price increases in recent years have now made heat pump water heaters more cost-effective over their lifetime — even before you account for the fixed charges.
A hot water heat pump uses 60–75% less energy than gas to heat the same amount of water. At current NZ electricity rates of around 30c/kWh and a typical heat pump COP of 4.0, the effective cost of heating water with a heat pump is approximately 7.5c per kWh. Gas costs roughly 12–15c per kWh of delivered heat — nearly double.
15-year total cost of ownership — all options compared
The true cost: purchase, installation, and 15 years of running. Source: Rewiring Aotearoa Electric Homes Technical Report, March 2024.
Your situation: what are you switching from?
The right approach depends on how many gas appliances you have. Pick the scenario that matches your home.
💧 Gas is only my hot water
This is the simplest switch and the biggest win. Replace the gas water heater with a heat pump, disconnect gas, and start saving immediately.
- One installation, one appointment
- Eliminate the gas fixed charge from day one
- Typical installed cost: $6,400–$9,700
- Payback period: 4–7 years
- No other appliances need to change
🔥 I also have a gas cooktop
Switch hot water first — it delivers 80% of the savings. Plan to switch the cooktop to induction later. Keep the gas connection until the cooktop goes.
- Switch hot water now: biggest energy saving
- Switch cooktop to induction at your own pace
- Once both are done, disconnect gas entirely
- The fixed charge keeps running until the last appliance goes
❄️ I have gas heating too
You have the most gas appliances — and the most to save. The recommended sequence is hot water first, then cooktop, then space heating, then disconnect.
- Hot water first: highest impact, simplest switch
- Induction cooktop second: relatively low cost
- Space heating last: may involve ducted or multi-split
- Total savings: potentially $3,000+ per year
🏠 I'm doing a renovation
A renovation is the perfect time to go fully electric. The incremental cost during a reno is much lower than a standalone retrofit.
- Electrical wiring is already being upgraded
- Plumbing is already being touched
- Builder can coordinate all trades efficiently
- Specify electric-only from the start
The switching sequence: step by step
Whether you're switching hot water only or going fully gas-free, here's the process.
The switching sequence
- Check what gas appliances you haveWalk through your home and list every gas appliance: hot water, cooktop, space heater, gas fireplace. Check your gas bill for the daily fixed charge amount. This tells you what you'll save when you disconnect.15 minutes — do this now
- Get quotes for a hot water heat pumpContact two or three licensed plumbers who install heat pump water heaters. Ask for an installed price including removal of the old gas unit, plumbing, and electrical work. Compare integrated (all-in-one) and split systems. Our product comparison tool shows every model available in NZ with pricing.Allow 1–2 weeks for quotes
- Check green finance optionsMost NZ banks now offer green home loans or sustainable loan top-ups. ASB, BNZ, Kiwibank, Westpac, and ANZ all have options. See our green finance guide for current rates.Check your bank's website or app
- Install the heat pump water heaterYour installer will disconnect and remove the old gas water heater, position and connect the new heat pump, run the electrical circuit, and commission the system. Most installations are completed in a single day.Typically 1 day for installation
- If hot water was your last gas appliance: disconnect gasContact your gas retailer to arrange disconnection. They will send a registered gasfitter to cap the gas line at the meter and remove the meter. Disconnection typically costs $100–$300. Once complete, the daily fixed charge stops. If you still have other gas appliances, keep the connection and plan to switch them next.Call your gas retailer — allow 1–2 weeks
- Set your heat pump timer and enjoy lower billsSet the timer to heat water overnight on a time-of-use plan (cheapest rates), or during the day if you have solar panels. Your first electricity bill after switching will show the difference.Start saving immediately
Which heat pumps are best for gas switchers?
If you're switching from gas, you want a system that maximises your savings and minimises installation complexity. Here's what matters most.
What matters most for gas switchers
- Choose an integrated system for the simplest swapAn all-in-one unit goes outside where your gas unit was, with no indoor cylinder needed. Fastest, most straightforward replacement.
- Consider a split system to keep your existing cylinderIf your current hot water cylinder is in good condition, a split heat pump can be retrofitted to it, significantly reducing costs.
- Size up — gas was unlimited, tanks are notGas instantaneous systems heat on demand with no storage limit. A family of four should look at 270–300L minimum.
- Confirm your switchboard can handle the new circuitGas systems use no electricity; a heat pump needs a dedicated circuit. Older switchboards may need an upgrade ($300–$800).
- Ask about solar-ready featuresMany heat pumps can be programmed to run during peak solar generation. If solar is on your roadmap, choose a system with timer modes.
Our picks for gas switchers
Three systems across different budgets, all proven in NZ conditions with low-impact refrigerants.
Rheem AmbiPower MDc-180
Integrated • 178L • R290
From ~$6,399
Indicative installed price
- COP:
- 4.5 at 19°C
- Noise:
- 48 dB(A)
- Suits:
- 1–3 people
- Best for:
- Budget entry point. Compact. Proven Rheem reliability.
Rinnai HydraHeat 275L
Integrated • 275L • R290
From ~$8,299
Indicative installed price
- COP:
- 4.7 at 19°C
- Noise:
- 45 dB(A)
- Suits:
- 2–5 people
- Best for:
- NZ-built head unit. Quietest in class. Works to −10°C.
Rheem AmbiPower 280e
Integrated • 280L • R290
From ~$7,499
Indicative installed price
- COP:
- 5.2 at 19°C
- Noise:
- 49 dB(A)
- Suits:
- 3–5 people
- Best for:
- Best efficiency in class. Strong NZ support.
Prices indicative as at May 2026. Verify with installers. See our full comparison for all models.
Ready to switch from gas?
Our installer partners specialise in gas-to-heat-pump conversions across Auckland. Licensed, insured, and experienced with the full disconnection process.
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