Key Takeaways
- Gas reheats fastest (30–60 minutes vs. 2–3 hours for electric)
- Heat pump uses least energy (saves $150–200/year after year 10)
- Gas wins on 10-year value; heat pump wins long-term
- Best choice depends on your family size, budget, and how long you’ll stay
When your cylinder fails, you don’t just replace it. You choose it. And that choice affects your comfort and bills for the next 10–15 years. Three main types exist: electric, gas, and heat pump. Each has pros and cons. Choosing the wrong one means overpaying for years. In this post, you’ll learn how each type works. You’ll also discover which one fits your home best.
Speed: How Fast Do They Heat Water?
Electric cylinder: 2–3 hours to reheat a full tank
After a family shower, you wait hours for the next person to have hot water. This matters in households with 4+ people.
Gas cylinder: 30–60 minutes to reheat
Gas burners heat water quickly. Back-to-back showers work fine. Recovery time is the big advantage here.
Heat pump cylinder: 1–2 hours to reheat
Heat pumps sit between electric and gas for speed. They’re slower than gas but faster than basic electric.
Winner: Gas (fastest recovery)
Running Costs: Monthly Bills
Electric cylinder: $35–50 per month
Electricity is the most expensive way to heat water. Over 10 years, costs add up fast.
Gas cylinder: $20–35 per month
Gas costs less than electricity per unit. This saves you $120 every year compared to electric.
Heat pump cylinder: $15–25 per month
Heat pumps use 50–70% less energy than electric. This is the cheapest option to run.
Winner: Heat pump (lowest bills)
Upfront Cost: What You Pay Today
Electric cylinder: $1,600–3,300 (cheapest)
Simple technology. Quick installation. No gas line work needed. Most affordable upfront.
Gas cylinder: $2,100–4,200 (mid-range)
More expensive than electric. But lower running costs make up for it over time.
Important: If you’re converting from electric to gas, add $400–1,000 for new gas line installation.
Heat pump cylinder: $4,300–7,500 (premium)
Most expensive upfront. But the long-term savings are huge.
Winner: Electric (lowest upfront cost)
Total Cost Over Time: What Matters Most
Look at the full 10-year cost, not just the upfront price. (Please note that these are estimations)
| Type | Upfront | 10-Year Running | Total |
|---|---|---|---|
| Electric | $2,500 | $4,200 | $6,700 |
| Gas | $3,200 | $2,800 | $6,000 ← Winner |
| Heat pump | $5,500 | $2,400 | $7,900 |
Gas is cheapest over 10 years. But here’s the twist: after year 10, heat pumps keep saving you $150–200 every year. By year 14, heat pump becomes cheaper overall.
Installation and Maintenance
Electric cylinder:
- Installation: 2–3 hours (simple)
- Maintenance: $600–1,200 over 10 years (element replacement, flushing)
- Inspections: none required
Gas cylinder:
- Installation: 3–4 hours (more complex)
- Maintenance: $800–1,600 over 10 years (burner servicing, inspections)
- Inspections: annual safety inspection required by law in NZ
Heat pump cylinder:
- Installation: 4–6 hours (most complex)
- Maintenance: $300–900 over 10 years (filter cleaning, rare repairs)
- Inspections: minimal needed
Winner: Heat pump (least maintenance)
Space Requirements and Placement
Electric cylinder:
- Size: compact
- Placement: flexible (cupboards, under stairs, tight spaces all work)
- Venting: none needed
- Electrical circuit: standard (most homes have capacity)
Gas cylinder:
- Size: slightly larger
- Placement: needs outdoor venting (often on roof or exterior wall)
- Venting: required; limits where you can put it
- Gas line: needs access to existing line or new line run
Heat pump cylinder:
- Size: largest of the three
- Placement: needs good airflow around unit (indoor or outdoor)
- Venting: none needed
- Electrical: may need dedicated circuit
- Noise: slight hum when running (barely noticeable)
Winner: Electric (most flexible placement)
Decision Tree: Which Type Is Right for You?
1. How many people live with you?
1–2 people (low usage) → Electric works fine
3–5 people (medium usage) → Gas or heat pump better
5+ people (high usage) → Gas (fastest) or heat pump (most efficient)
2. Do you have a gas line already?
YES → Gas is a good option (no extra cost)
NO → Electric or heat pump (gas line upgrade is expensive)
3. What matters most to you?
Lowest upfront cost → Electric
Lowest monthly bills → Heat pump
Balanced cost and speed → Gas
Most environmentally friendly → Heat pump
Simplest system → Electric
4. Will you stay in this home 10+ years?
YES → Heat pump or gas (long-term savings)
NO → Electric (lowest upfront)
Real-Life Scenarios
Young couple, renting: Electric. Upfront cost is lowest. You won’t own the home long-term.
Family of four, owned home, has gas line: Gas. High hot water demand. Gas line already there. Saves $120/year versus electric.
Family of four, owned home, values environment: Heat pump. Long-term savings + low carbon footprint. Willing to pay upfront.
Single person, small flat: Electric. Low usage. Simplest system. Lowest upfront cost.
Common Questions
Q: Which is most reliable?
All three are reliable. Electric is simplest (fewer parts). Gas needs annual inspection but is industry-standard. Heat pump is newer tech but comes with good warranty.
Q: Can I switch later (electric now, gas later)?
Yes, but it costs extra if you need plumbing or gas line work. Choose right the first time.
Q: Which is quietest?
Electric and gas are silent. Heat pump has a slight hum (barely noticeable).
Q: How do I know what size I need?
We size it based on your household size and usage. Bigger isn’t always better — it costs more to run.
What To Do Next
- Decided which type? Get your replacement quote — takes 60 seconds.
- Want detailed pricing? See our cost breakdown.
- Still deciding? Read the signs your cylinder needs replacing.
Every home is different. The right cylinder for your family might be wrong for another.
Get a free assessment today or call 09 525 733. We’ll recommend the best option for your needs.
