iStore vs Quantum: Which Heat Pump Is Better? (2026)
Quick Verdict
Quantum is the more efficient choice with a higher COP rating, meaning lower running costs over time, while iStore is more budget-friendly with a lower upfront cost starting from $2,800.
Side-by-Side Comparison
| Feature | iStore | Quantum |
|---|---|---|
| Price range (installed) | $2,800 - $4,400Lower | $3,250 - $4,450 |
| COP (efficiency) | 3.2 | 4.53Higher |
| Tank warranty | 5 years | 5 years |
| Compressor warranty | 5 yearsLonger | 2 years |
| Noise level | 49dB | 48dBQuieter |
| Annual running cost | ~$370/yr | ~$261/yrLower |
| Refrigerant type | R134a | R134a |
| Country of manufacture | Australia | Australia |
| Australian made | No | No |
| Best for | Budget-conscious households wanting maximum rebate impact and simple installation | Small households needing a 150L or 200L tank, and anyone outside Victoria who wants a long-established Australian brand |
Price Comparison
iStore starts from $2,800 installed (before rebates), while Quantum starts from $3,250. That is a difference of roughly $450 at the entry level. iStore is the more budget-friendly option upfront, though Quantum may deliver savings through lower running costs over time. Both prices are for fully installed systems before government rebates and STCs, which can reduce the out-of-pocket cost by $1,000 to $3,000 depending on your state.
Efficiency Comparison
COP (Coefficient of Performance) is the key efficiency metric for heat pumps. A higher COP means more heat output per unit of electricity consumed. iStore achieves a COP of 3.2, while Quantum reaches 4.53. The Quantum is 42% more efficient, which translates to roughly $109 less per year in running costs. Over a 10-year lifespan, that efficiency advantage adds up to approximately $1,090 in savings.
Warranty Comparison
iStore offers a 5-year tank warranty and 5-year compressor warranty. Quantum offers a 5-year tank warranty and 2-year compressor warranty. Both brands offer the same tank warranty length, so warranty coverage is comparable.
Noise Comparison
Noise is an important consideration, especially for suburban installations where the unit may be close to bedrooms or neighbouring properties. iStore publishes 49dB for its quietest model, and Quantum publishes 48dB. The Quantum is quieter at 48dB. At this level, you may want to consider placement carefully to avoid disturbing bedrooms or neighbours.
Climate Suitability
The type of refrigerant a heat pump uses significantly affects its performance in cold weather. iStore uses R134a refrigerant, while Quantum uses R134a. Both units use the same refrigerant type, so cold-weather performance should be comparable. R134a performs well in moderate climates but may lose some efficiency in very cold conditions.
Pros and Cons
iStore
Pros
- Most affordable option
- Australian owned and supported
- Simple installation
- Good rebate value (low cost means rebates cover more)
- Widely available
Cons
- Lower COP than premium brands
- Shorter warranty
- Noisier than split systems
- Higher running costs long-term
- Units manufactured overseas
Quantum
Pros
- Four tank sizes from 150L to 340L, the widest range here
- A 150L option, which almost no other brand offers
- Australian company with a manufacturing facility at Seaford, South Australia
- Propane (R290) across the range
- On the register since 2014, so the models have a long track record
Cons
- Not on the Solar Victoria product list at all, so a Quantum does not qualify for the Victorian hot water rebate
- Only 2 years on the electrical and refrigeration parts, the shortest here
- Quantum publishes no labour warranty term
- The product pages and the 270L data sheet disagree on the minimum operating temperature (-10C against -15C)
- 50 dB on the 150L and 200L
Which Should You Choose?
Choose iStore if...
- You want a lower upfront cost (from $2,800 vs $3,250)
Choose Quantum if...
- You want the best efficiency and lowest running costs (COP 4.53 vs 3.2)
- Quiet operation matters to you (48dB vs 49dB)
- You want lower annual running costs (~$261/yr vs ~$370/yr)
Buying in Victoria? Stack up to $2,700 in rebates
Whichever brand you pick, Victorian households can stack the Solar Victoria Hot Water Rebate ($1,000-$1,400), the Victorian Energy Upgrades discount ($500-$2,000), and federal STCs ($500-$1,200) ahead of the 1 March 2027 gas ban deadline.
Heat pump guides
- Every Australian heat pump rebate, with the dated changes
- The best heat pump hot water brands in Australia
- Heat pump hot water cost in Australia
- Victoria heat pump rebates
- New South Wales heat pump rebates
- Queensland heat pump rebates
- South Australia heat pump rebates
- Australian Capital Territory heat pump rebates
- Western Australia heat pump rebates
- Tasmania heat pump rebates
- Northern Territory heat pump rebates
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