Aquamax Hot Water Systems: A Buyer's Guide
About Aquamax
Aquamax is an Australian hot water brand with a long history in the residential and light commercial market. Known for robust storage hot water systems built to handle Australian conditions, Aquamax has been a trusted specification choice for plumbers and a reliable replacement option for homeowners across the country.
The Aquamax range available at PlumbingSales.com.au focuses on electric storage hot water systems — the most widely installed hot water technology in Australia — with capacities from 80 litres through to 400 litres to suit everything from small apartments to large households and light commercial properties. A stainless steel natural gas model is also available for properties requiring gas-boosted storage.
Electric Storage Hot Water: Why It's Still the Most Common Choice
Despite the growth of heat pump and continuous flow systems, electric storage hot water remains the most common hot water technology in Australian homes. There are a few straightforward reasons for this.
Electric storage systems are relatively simple to install, widely understood by licensed plumbers, and compatible with off-peak electricity tariffs — which can significantly reduce running costs when the system is set to heat during low-demand overnight periods. They also require minimal maintenance compared to systems with gas burners or heat pump compressors, and replacement is typically a like-for-like swap that keeps installation costs down.
For rental properties, medium-density housing, and older homes where gas isn't connected, an electric storage system is often the most practical and cost-effective solution. Aquamax's electric storage range covers this need across a wide capacity range, with both single element and twin element configurations available.
Single Element vs Twin Element: What's the Difference?
One of the first decisions when choosing an Aquamax electric storage system is whether you need a single element or twin element model.
Single element systems have one heating element, typically positioned in the lower portion of the tank. The entire tank volume is heated from a single point, which is efficient for off-peak tariff setups where the system heats overnight and holds temperature through the day. Aquamax single element models in this range are rated at 3.6kW and are available from 80L to 400L.
Twin element systems have two heating elements — one upper and one lower — which gives the system greater flexibility. The upper element can heat a smaller volume of water quickly during peak demand periods, while the lower element handles the full tank volume for off-peak heating. Twin element models suit larger households with variable hot water demand patterns, or properties where peak-rate top-up heating is needed. Aquamax twin element models are available from 250L to 400L, with the 400L twin element rated at 4.8kW.
For most standard residential installations, a single element system on an off-peak tariff is sufficient. Twin element models are worth considering for larger households, investment properties with high and unpredictable occupancy, or where the electricity plan allows for peak-rate top-up without significantly affecting running costs.
Choosing the Right Aquamax Capacity
Getting the tank size right matters. Too small and you'll run out of hot water during peak use periods; too large and you're paying to heat water that never gets used. As a general guide:
| Household Size | Recommended Capacity | Suitable Aquamax Model |
|---|---|---|
| 1–2 people | 80L–125L | 981080G7 / 981125G7 |
| 2–3 people | 125L–160L | 981125G7 / 971160G7 |
| 3–4 people | 160L–250L | 981160G7 / 991250G7 |
| 4–5 people | 250L–315L | 991250G7 / 991315G7 |
| 5+ people or light commercial | 315L–400L | 991315G7 / 991400G7 |
These are general guidelines. Actual hot water demand varies based on shower duration, whether you have a dishwasher, and usage patterns across the household. For properties on off-peak tariffs, some plumbers recommend sizing up slightly — a larger tank heated overnight at off-peak rates costs little more to run than a smaller one, but provides a bigger buffer against running out during the day.
For twin element installations, the 250L (992250G7), 315L (992315G7), and 400L (992400G8) models suit medium to large households where demand is high or variable.
The Aquamax G390SS-NG: Stainless Steel Gas Storage
For properties with natural gas connected and a preference for gas-boosted storage, the Aquamax G390SS-NG offers a 390-litre stainless steel cylinder with natural gas heating. Stainless steel construction provides superior corrosion resistance compared to vitreous enamel-lined tanks, which can be a consideration in areas with harder or more corrosive water supplies.
At 390 litres, the G390SS-NG suits large households, dual-occupancy properties, and light commercial applications where high hot water demand needs to be met reliably. Gas storage systems recover faster than electric equivalents, making them a practical choice where large volumes of hot water are needed across a shorter window of the day.
Key Specifications Across the Aquamax Electric Range
All Aquamax electric storage models in this range share the following key specifications:
- Element rating: 3.6kW (single element), 3.6kW lower / variable upper (twin element), 4.8kW (400L twin element)
- Warranty: 10-year cylinder warranty across the G7 and G8 series
- Installation: Must be installed by a licensed plumber in accordance with AS/NZS 3500 and applicable state requirements
- Anode: Sacrificial magnesium anode protects the tank lining — anode inspection and replacement at manufacturer-recommended intervals extends tank life
- Thermostat setting: Australian standards require storage hot water systems to be set to a minimum of 60°C to prevent Legionella growth; tempering valves are required at the outlet where water is delivered to bathrooms at temperatures above 50°C in residential installations
Replacing an Aquamax Hot Water System
When an existing electric storage system fails, replacement is typically straightforward for a licensed plumber. In most cases, an equivalent capacity unit can be swapped directly, using the existing wiring, pipework, and fittings. Key considerations for a replacement include:
Like-for-like capacity — matching the existing tank size avoids the need to resize pipework or electrical connections. If the existing system was undersized, a replacement is an opportunity to step up in capacity.
Element configuration — if replacing a twin element system, confirm whether the replacement needs to be twin element to suit the existing wiring and tariff arrangement.
Tempering valve — if not already present, a tempering valve should be installed at the outlet to comply with current Australian Standards for hot water delivery temperatures in bathrooms and laundries.
Flexible hoses and isolation — quality braided flexible hoses and an isolation valve on the cold water inlet are standard components for a hot water system connection. PlumbingSales.com.au stocks a full range of flexible hoses suitable for hot water system connections.
Where to Buy Aquamax Hot Water Systems
PlumbingSales.com.au stocks the Aquamax electric storage hot water range from 80L to 400L, including single element and twin element models, plus the G390SS-NG stainless steel gas storage unit. With over 60 years of industry experience and a 4.9-star rating from more than 7,200 verified customer reviews, we're a trusted supplier for licensed plumbers and trade professionals across Australia.
Browse the full Aquamax hot water systems range online or call our knowledgeable team on 1800 341 972 if you need help selecting the right model for your job. You can also email us at [email protected] — we're happy to assist with product selection, specifications, and availability.
For the full range of hot water systems across all brands, visit our hot water systems category.