Hot Water System Buying Guide: Gas vs Electric vs Solar
A new hot water system is a 10–15 year decision that affects your power bill, your shower pressure and your weekend mornings. After installing hundreds of systems across the Adelaide Hills, here's the honest breakdown I give my own family.
The 4 Main Options in 2025
| System Type | Upfront Cost (Installed) | Annual Running Cost | Best For |
|---|---|---|---|
| Continuous Flow Gas | $2,200 – $3,200 | $450 – $700 | Most Hills homes with mains gas |
| Electric Storage | $1,400 – $2,400 | $700 – $1,400 | Small budgets, off-peak tariff homes |
| Heat Pump | $3,800 – $5,500 (after rebate) | $200 – $450 | Energy-conscious homeowners, solar households |
| Solar (Roof Panel) | $4,500 – $7,000 (after rebate) | $150 – $400 | North-facing rooves, families of 4+ |
Continuous Flow Gas — The Default for Most Hills Homes
If you've got mains gas or LPG, a continuous flow (instantaneous) unit is hard to beat. You only heat water when you need it, so there's no standing heat loss. Brands I install regularly include Rinnai Infinity and Rheem Metro.
Heat Pump — The Sleeper Winner
Heat pumps are the system I install most for households who want to slash their power bill. They use the same technology as a reverse-cycle air-con and use roughly a third of the electricity of a standard electric storage unit. South Australian government and STC rebates can knock $1,000–$1,500 off the upfront price.
Pros
- Up to 70% cheaper to run than electric storage
- Eligible for federal STC rebates and SA government incentives
- Pairs beautifully with rooftop solar (run during the day)
- No gas required — perfect for all-electric homes
Cons
- Higher upfront cost
- Slight ambient noise (similar to a fridge)
- Recovery time is slower than continuous gas
The Sizing Mistake Most Homeowners Make
Sizing isn't about the size of the tank — it's about peak demand. A family of four running back-to-back showers needs different capacity than a couple. Here's the rough sizing I work from:
| Household Size | Gas Continuous (L/min) | Storage (Litres) |
|---|---|---|
| 1–2 people | 16 L/min | 125–160 L |
| 3–4 people | 20–26 L/min | 250–315 L |
| 5+ people | 26 L/min (often dual) | 315–400 L |
"Don't buy the cheapest unit and hope. A properly sized system saves you money every single year you own the house."
Frequently Asked Questions
How long does a hot water system installation take?+
Most like-for-like swaps take 3–4 hours. New installations or system changes (e.g. electric to gas) can take a full day.
Do you offer same-day replacement?+
Yes — if your system fails, we carry the most common Rinnai and Rheem units on the truck and can often have hot water back the same day.
Are rebates included in the quote?+
Yes. We deduct any eligible STC and SA Government rebates directly off the upfront cost so you don't pay and chase.
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