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🏷️ Brand:
🔢 Model Number:
📦 Volume: L
📏 Width: mm
📐 Height: mm
🌍 Manufactured In:
🛠️ Heat Exchange Material:
🛡️ Cylinder/Heat-Exchange Warranty: Years
🔇 Noise Level: dBa
⚖️ Dry Weight: kg
📡 WiFi Controller:
⏲️ Built-In Timer:
💡 LED/LCD Status Indicator:
📊 Coefficient of Performance (COP):
⚡ Energy Source:
IMPORTANT - Default supply is Natural Gas — please leave a note at checkout if LPG is required where available.
Vulcan DUOMAX 20 Continuous Flow Gas Hot Water System – Brisbane & Gold Coast
Compact. Reliable. Endless hot water for Aussie homes.
The Vulcan DUOMAX 20 delivers powerful, energy-efficient continuous-flow performance for medium-sized Australian families.
With a flow rate of 20 L/min, it supplies instant hot water to two bathrooms simultaneously—ideal for households of 3 to 5 people.
Installed by JR Gas & Water, Brisbane and Gold Coast’s award-winning plumbing team, the DUOMAX 20 offers dependable performance, safe operation and expert installation backed by a lifetime workmanship warranty.
Product Overview
Engineered for reliability and efficiency, the Vulcan DUOMAX 20 provides instant, continuous hot water with no storage tank.
Its 6-Star energy rating keeps running costs low while reducing emissions, and it’s fully compatible with both Natural Gas and LPG.
Compact and wall-mounted, this slimline outdoor unit is perfect for homes with limited space yet high hot-water demand.
Built in Australia, the DUOMAX 20 is designed for tough local conditions and offers long-term durability with nationwide parts availability.
Key Features & Why They Matter
1️⃣ 20 L/min Flow Rate – Supports two bathrooms for medium to large homes.
2️⃣ Continuous Flow Design – Endless hot water on demand, no storage needed.
3️⃣ 6-Star Energy Efficiency – Lower gas bills and reduced emissions.
4️⃣ Slimline Outdoor Unit – Compact wall-mount design for tight spaces.
5️⃣ Precise Temperature Control – Safer water for families and kids.
6️⃣ Natural Gas or LPG Compatible – Flexible for any property.
7️⃣ Australian-Made Build – Reliable construction with local support.
8️⃣ 10-Year Heat Exchanger Warranty – Plus 3 years parts & labour coverage.
Who Is It Best For?
✅ Families of 3 – 5 people
✅ Homes with 2 bathrooms
✅ Upgrading from electric storage or older gas units
✅ Builders and renovators needing compact high-efficiency hot water
Why Choose JR Gas & Water
🧰 Licensed plumbers & gas fitters handling supply and installation
✅ QBCC Form 4 gas compliance certificate provided
🏆 3× ProductReview Award Winner (2023 – 2025)
🧼 Old system removed and site left clean
📅 Same-day or next-day installation in most suburbs
💬 Expert advice and post-installation support
Technical Specifications
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Flow Rate: 20 L/min (@ 25 °C rise)
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Energy Rating: 6 Stars
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Gas Type: Natural Gas / LPG
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System Type: Continuous Flow (Tankless)
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Installation: Outdoor wall mount only
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Warranty: 10 years heat exchanger / 3 years parts & labour
Common Questions
Q: Will the DUOMAX 20 suit my family?
Yes – it’s ideal for families of 3 – 5 with two bathrooms.
Q: Can it run multiple taps at once?
Yes – with 20 L/min flow it can handle two bathrooms simultaneously.
Q: Is LPG available?
Yes – the DUOMAX 20 comes in Natural Gas and LPG models.
Q: What is the warranty?
10 years on the heat exchanger and 3 years on parts and labour.
Q: Can it be installed indoors?
No – the DUOMAX 20 is designed for safe outdoor installation only.
🔥 Instant Gas Hot Water System Package Selection Guide
(Please rotate your mobile device for easier viewing)
Choosing the right instant gas hot water system package depends on your current setup, whether plumbing or gas upgrades are needed, and if any relocation or compliance work is required. Use this guide to compare package levels and find the best match for your home.
We know things don’t always go to plan — and most customers aren’t plumbers — so we’re flexible and happy to adjust your installation package if needed.
💡 Which Package Is Right for You?
IMPORTANT: All online packages are for EXTERNAL installations only. For internal installations, please request a quote.
✅ Base – For compliant replacements of existing identical EXTERNAL instant systems
Best for like-for-like swaps where the existing system is fully compliant and the same make/model/series. No gas line changes, electrical work, or plumbing alterations.
🧰 Example: Replacing a Rinnai B26 with a Rinnai B26 on the same wall with compliant gas supply.
✅ Silver – For minor upgrades
Includes small plumbing adjustments and a new valve kit. No gas line modifications or system disposal. Designed for customers on a budget upgrading to a slightly different model.
🧰 Example: Replacing a Rheem 26 with a Rinnai B26 where the gas line is compliant but pipework needs modifying to suit and valves need replacing for warranty.
🏆 Gold – Best Seller – For standard installations
Covers everything needed for a standard upgrade: removal of old unit, plumbing changes, valves, and a tempering valve.
🧰 Example: Upgrading from an old Bosch 16P Instant to a new Bosch 16H that requires a tempering valve, with full plumbing refresh and removal of old unit.
💰 Sapphire – Best Value – For installations requiring gas upgrades
Everything in the Gold package plus gas line upgrades or a new gas main from meter to unit to ensure safe and compliant installation.
🧰 Example: Switching from a smaller capacity like a 13L to a larger 26L instant system that needs a larger gas main and full plumbing setup.
✅ Diamond – For major gas plumbing overhauls
Adds extended gas runs, upgraded regulators or meter connections and a new power point. Ideal for homes switching to gas or where old systems were severely non-compliant.
🧰 Example: Changing from electric to gas in a home with no current gas line in the right location, requiring a full line upgrade.
✅ Platinum – The ultimate package
Includes everything: relocation, extensive plumbing, and full gas installation or rerouting. Ideal for complex installs or new system placements.
🧰 Example: Moving the hot water system to the opposite side of the home and running a new gas line with full setup and all compliance.
🏆 Package Comparison Guide
Here’s your revised Package Comparison Guide with the new line added as the third row, directly under “Existing System Must Be Same Type & Location”:
| Feature | Base | Silver | Gold 🏆 | Sapphire 💰 | Diamond | Platinum |
|---|---|---|---|---|---|---|
| ✅ Existing System Must Be Identical Make/Model as Purchase with Compliant Installation | ✅ | ❌ | ❌ | ❌ | ❌ | ❌ |
| ⚠️ Includes gas supply upgrade to suit larger capacity unit (e.g. 16L replaced with 16L or larger) | ❌ | ❌ | ❌ | ✅ | ❌ | ✅ |
| ✅ Form 4 (Compliance Certificate) | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| 🔧 Pipework Alterations | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ |
| 🔧 Valve Kit | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ |
| 📏 Pipework Included (m) | ❌ | 2m | 4m | 14m | 4m | 24m |
| 🧱 Support Base (if ground is soft/uneven) | ❌ | ❌ | ✅ | ✅ | ✅ | ✅ |
| 🗑️ FREE Old System Disposal | ❌ | ❌ | ✅ | ✅ | ✅ | ✅ |
| 🔧 Powerpoint | ❌ | ❌ | ❌ | ✅ | ✅ | ✅ |
| 🔥 Gas Line Upgrade / New Gas Main | ❌ | ❌ | ❌ | ✅ | ❌ | ✅ |
| 📦 System Relocation | ❌ | ❌ | ❌ | ❌ | ❌ | ✅ |
| ✅ Requires Compliant Existing Install | ✅ | ✅ | ❌ | ❌ | ❌ | ❌ |
🔧 Trusted Materials, Backed by Quality
We only use high-grade parts from reputable manufacturers:
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Valves – AVG, RMC, Rye Metal
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Copper Pipe – Kembla Type B, Crane
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PEX Plumbing – Ezipex
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Insulation – eFlex, K-Flex
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Brassware – Brasshards
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Gas Components – Bromic, EziPress, Viega
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Sealants – Loxeal
Let us know if you have any specific brands or components you’d like us to use.
🛠 Need Help Choosing?
Still unsure which package is right for your home?
The JR Gas & Water team is here to help.
ZipPay – 6-Month Interest-Free on All Products
ZipPay allows you to buy now and pay later, offering flexible, interest-free payments for up to 6 months on all JR products. It’s easy to set up, and you can customize your repayment schedule to suit your budget. Payments can be made weekly, fortnightly, or monthly, with a $6 fee if the balance isn’t paid off by the due date.
Humm – Up to 12 Months Interest-Free
Humm provides interest-free payment plans on purchases up to $30,000, perfect for both small and large buys. For items over $2,000, you can spread payments over 12 months. Humm also offers flexibility in scheduling payments based on when you get paid
Afterpay – 8 Weeks, No Interest
With Afterpay, spread the cost of purchases across four equal installments, due every two weeks, over an 8-week period. There’s no interest, and as long as payments are made on time, there are no fees. Perfect for purchases between $100 and $1,500
Plenti Finance – For Reclaim Systems Only
Plenti Finance is available exclusively for Reclaim Energy systems. This option offers tailored repayment terms with competitive interest rates, helping make eco-friendly choices more affordable. For more detailed information on Plenti’s terms and eligibility for Reclaim systems, visit the Reclaim Energy finance page
If you're in Queensland and considering a new electric hot water system, JR Gas & Water is the company to choose. Here's why:
Experience and Expertise: JR Gas & Water has over 10 years of experience in the gas and plumbing industry. Their team of licensed and insured professionals is highly skilled and knowledgeable about all aspects of electric hot water system installation, maintenance, and repair. They can provide expert advice on the best system for your needs and ensure a smooth installation process.
Quality Products: JR Gas & Water uses only high-quality products from trusted brands to ensure your electric hot water system is reliable and efficient. They also offer a range of options to suit different budgets and requirements.
Competitive Pricing: JR Gas & Water offers competitive pricing for their electric hot water systems, ensuring that you get a great value for your investment. They also provide a detailed quote upfront, so there are no surprises or hidden costs.
Customer Service: JR Gas & Water is committed to providing excellent customer service. They are always available to answer any questions or concerns you may have and are committed to ensuring your satisfaction.
Local Business: JR Gas & Water is a locally owned and operated business in Queensland. By choosing them for your electric hot water installation, you are supporting a local business and contributing to the local economy.
Warranty and Guarantee: JR Gas & Water provides a warranty and guarantee on all their products and services, giving you peace of mind knowing that your system is covered in case of any issues.
Energy Efficiency: Electric hot water systems can be energy efficient, and JR Gas & Water can help you choose the right system for your needs. They can provide advice on energy-saving features and options, such as timers and thermostats, to help you save on your energy bills.
Safety: JR Gas & Water is committed to safety and ensuring that all installations are done to the highest safety standards. They are also familiar with local safety regulations and requirements, ensuring that your electric hot water system is installed safely and in compliance with all relevant codes.
JR Gas & Water is a reliable and experienced choice for your electric hot water system installation in Queensland. With a commitment to quality products, competitive pricing, excellent customer service, and safety, they can help you make the switch to a more efficient and cost-effective solution for your hot water needs. Contact them today to learn more about their services and how they can help you.