RANGE OF AVAILABLE REPLACEMENT SYSTEMS
ENVIROSUN SOLAR HOT WATER INSTALLATION
Envirosun THX300/40 Installation Brisbane & Gold Coast
JR Gas & Water supplies and installs the Envirosun THX300/40 closed-circuit solar hot water system across eligible Brisbane and Gold Coast service areas. It is a roof-mounted thermosiphon system that combines the hot water storage tank and two solar collectors into one roof-mounted installation.
The current Envirosun THX300/40Se provides 304 litres of nominal storage and uses two E20HS flat-plate collectors. Unlike Envirosun's standard open-circuit TS models, the THX uses an indirect closed solar circuit with a separate jacket chamber, giving the collector circuit additional protection in frost-prone conditions and areas where water quality can create problems for direct-circulation solar systems.
Because the tank and collectors are all installed on the roof, the success of a THX300/40 installation depends heavily on the property. Roof structure, usable space, solar exposure, pitch, safe access, lifting requirements, existing plumbing and the selected electric or gas boosting arrangement all need to be considered before installation.
Envirosun THX300/40 at a glance: The current THX300/40 is a 304L closed-circuit thermosiphon solar hot water system with a roof-mounted stainless steel tank and two E20HS flat-plate collectors. The closed solar circuit is designed to improve freeze and collector-fouling protection. Electric and gas-boosted configurations are available, and JR Gas & Water installs the system across eligible Brisbane and Gold Coast areas subject to roof, access and installation suitability.
Envirosun THX300/40 Supply & Installation at a Glance
Product Type
Closed-circuit roof-mounted thermosiphon solar hot water system.
Storage Capacity
304L nominal storage in Envirosun's current THX300/40 specification.
Solar Collectors
Two E20HS flat-plate collectors mounted with the storage tank on the roof.
Installation Area
Professional supply and installation across eligible Brisbane, Gold Coast and surrounding South East Queensland areas.
Who Is the Envirosun THX300/40 Best For?
Roof-Mounted Solar Buyers
The THX300/40 suits properties where a thermosiphon layout makes sense and the roof can accommodate both the storage tank and solar collectors rather than requiring a separate ground-level tank.
Closed-Circuit Solar Applications
Envirosun specifically positions the THX configuration for greater freeze and collector-fouling protection than its open-circuit TS system, which can matter in colder locations or where water quality is a concern.
Family Solar Hot Water
The 304L storage capacity places the THX300/40 in Envirosun's larger roof-mounted solar category, making it worth considering where household demand justifies a family-sized solar storage system.
PRODUCT SUITABILITY
Is the Envirosun THX300/40 Right for My Home?
A Good Choice If...
You want roof-mounted solar hot water, have sufficient usable roof space, prefer a thermosiphon system without an active solar circulation pump and value the additional freeze and water-quality protection provided by the THX closed-circuit design.
Consider Another Option If...
Your roof cannot practically support the complete system, access is difficult, roof space or solar exposure is poor, or you would prefer to keep the storage tank at ground level. An active split solar or heat pump system may make more sense on some properties.
JR Should Check First If...
You are converting from a ground-mounted system, relocating the installation, changing between electric and gas boosting, have unusual roof construction or are unsure whether the existing plumbing and roof position can be reused.
How Many People Does the Envirosun THX300/40 Suit?
Envirosun currently groups its TS and THX thermosiphon range across storage capacities from 167L to 304L and describes the wider range as covering approximately two to six people. That is a range-level guide rather than a fixed occupant rating for every THX300/40 installation.
The THX300/40 provides 304L nominal storage, but correct sizing also depends on shower length and flow rates, number of bathrooms, bath use, simultaneous hot water demand, dishwasher and laundry habits, solar contribution and when the household uses its hot water.
A household with concentrated morning or evening usage can place greater demand on the booster and stored hot water than another household with the same number of occupants. JR should therefore match the system to actual hot water usage rather than selecting it from occupant count alone.
How Does the Envirosun THX300/40 Work?
The THX300/40 uses the thermosiphon principle. The storage tank is mounted above the collectors on the roof. As the solar circuit heats up, warmer fluid naturally rises while cooler fluid moves downward toward the collectors, creating circulation without the active solar pump required by a split system.
The THX difference is its indirect closed-circuit design. Rather than circulating household water directly through the collectors, the solar collector circuit transfers heat through a separate jacket arrangement. Envirosun specifically identifies this configuration as providing additional freeze and collector-fouling protection.
The process is straightforward: sunlight heats the E20HS collectors → thermosiphon circulation transfers solar heat through the closed circuit → heat is transferred into the storage tank → hot water is stored for household use → the booster supplies additional heating when required.
Key Features of the Envirosun THX300/40
304L Stainless Steel Tank
The current THX300 uses a 304L nominal roof-mounted tank. Envirosun specifies grade 444 ferritic stainless steel for its current TS and THX tank construction.
Two E20HS Solar Collectors
The system uses two E20HS flat-plate collectors with selective absorber surfaces, copper risers and headers, insulation and tempered solar glass.
Closed Solar Circuit
The THX uses a separate indirect solar circuit instead of passing normal household water directly through the solar collectors.
Freeze Protection
Envirosun specifically identifies the THX configuration as the thermosiphon option designed for frost-prone locations.
No Solar Circulation Pump
The roof-mounted thermosiphon layout circulates heat naturally, so an active circulation pump is not required for normal solar heat transfer.
Electric or Gas Boost Options
The THX300/40 is available in electric and gas-boosted configurations so the final system can be matched to the available services and installation requirements.
Envirosun THX300/40 Specifications
| Specification | Details |
|---|---|
| Brand | Envirosun |
| Electric Model | THX300/40Se |
| Gas Model | THX300/40Sg |
| Product Type | Closed-circuit thermosiphon solar hot water system |
| Storage Capacity | 304L nominal |
| Installation Type | Roof-mounted tank and collectors |
| Tank Model | TS300/C/E24/S2 |
| Tank Material | Grade 444 stainless steel |
| Tank Footprint | 650 × 2,150mm |
| Tank Height | 600mm |
| Tank Empty Mass | 77kg |
| Tank Full Mass | 393kg |
| Collectors | 2 × E20HS flat-plate collectors |
| Collector Footprint | 1,235 × 2,000mm each |
| Collector Height | 70mm each |
| Collector Empty Mass | 27.5kg each |
| Collector Full Mass | 29.2kg each |
| Electric System Footprint | 2,238 × 2,600mm |
| Electric System Empty Mass | 135kg |
| Electric System Full Mass | 454kg |
| Electric Boost Capacity | 140L |
| Electric Booster | 2.4kW |
| Electric CER Code | TS300/40/C/E24/S2/E20HS |
| Gas Boost Rate | Up to 26L/min |
| Gas Consumption | 188MJ/hr |
| Gas Heat Output | 42kW |
| Gas CER Code | TS300/40/C/GR26/S2/E20HS |
Current manufacturer specification: although the product family is called THX300, Envirosun currently publishes the storage capacity as 304L. Electric and gas-boosted models have different complete-system masses and booster specifications, so the selected variant should be used when confirming installation requirements.
INSTALLATION REQUIREMENTS
What Is Required to Install the Envirosun THX300/40?
The THX300/40 places both the storage tank and solar collectors on the roof. That makes roof suitability a central part of the installation rather than a secondary consideration.
Sufficient usable roof area for the complete system
Appropriate roof structure and mounting conditions
Suitable roof pitch and solar exposure
Safe installer access to the roof
Safe lifting and positioning of the equipment
Suitable hot and cold water pipework
Required pressure and safety valves
Compliant relief and drainage arrangements
Suitable electric or gas booster services
Tempering where required
Practical future service access
Licensed installation and commissioning
Roof height, pitch, construction, access, lifting requirements, existing system type and booster configuration can materially change the installation scope.
What's Included With Envirosun THX300/40 Installation?
Standard Installation
The applicable JR installation package covers the labour and materials described in the live product selector. Depending on the package, this may include removal of the existing system, roof installation of the tank and collectors, plumbing connections, applicable valves and connection of the selected booster.
Compliance & Commissioning
The completed THX installation is connected and checked for correct operation, including plumbing connections, safety components, solar operation and the electric or gas booster where applicable.
Possible Additional Work
Difficult roof access, crane or specialised lifting requirements, relocation, structural work, unusual roof mounting, extended pipework, gas alterations, electrical upgrades or major changes from the existing installation may require additional work or quotation.
How Much Does Envirosun THX300/40 Installation Cost?
Current Envirosun THX300/40 supplied-and-installed pricing is shown in the live product and installation selector above. Keeping current pricing within the commercial product area avoids hard-coding a price into long-form content that may become outdated.
Final installation cost depends on whether the job is a like-for-like rooftop solar replacement or a conversion from another system, along with roof height, access, lifting requirements, existing plumbing, valves, electric or gas booster requirements, relocation and any additional mounting or structural work.
A straightforward replacement of a compatible roof-mounted thermosiphon system can require less alteration than converting a ground-level electric, heat pump or active split solar installation to the THX roof-mounted layout.
BRISBANE INSTALLATION
Envirosun THX300/40 Installation Brisbane
JR Gas & Water supplies and installs the Envirosun THX300/40 across eligible Brisbane service areas. When replacing an existing roof-mounted solar system, JR can assess whether the current roof position, plumbing routes, mounting area and booster services are suitable for the THX installation or need to be altered.
For Brisbane properties changing from ground-mounted electric storage, a heat pump or active split solar, the installation requires more planning because the 304L tank and both solar collectors move onto the roof. Safe access, lifting method, structural suitability, available solar exposure and the pipe route between the roof and home services become central to the job.
JR also services eligible surrounding areas including Logan, Ipswich, Moreton Bay and Redlands, with final availability and installation requirements determined by the individual property.
GOLD COAST INSTALLATION
Envirosun THX300/40 Installation Gold Coast
Gold Coast THX300/40 installation begins with confirming that the roof can practically accommodate the complete thermosiphon system and remain accessible for installation and future servicing. This is particularly important when replacing a ground-mounted system or relocating an older roof-mounted solar unit.
Where an existing thermosiphon system is being replaced, some of the existing plumbing route may remain useful if it is suitable for the new installation. Renovations and technology conversions can require more extensive changes to pipework, booster services and roof mounting.
The THX300/40 is therefore best selected for a property that genuinely suits roof-mounted storage rather than simply because it offers solar water heating. JR's installation approach focuses on whether the whole system works for the site.
Can the Envirosun THX300/40 Replace My Existing System?
Replacing Roof-Mounted Solar
This is usually the most direct replacement scenario, but roof condition, mounting area, plumbing, booster services, access and the new system footprint still need to be checked.
Replacing Active Split Solar
A split system keeps its storage tank at ground level. Changing to the THX moves the storage component onto the roof and can require substantial plumbing and mounting alterations.
Replacing Electric or Heat Pump Hot Water
Conversion can be possible where the roof and services are suitable, but it is not a simple tank swap. The new roof-mounted solar equipment and associated pipework must be incorporated into the property.
Replacing Another Brand
The existing system does not have to be Envirosun. Replacement suitability depends on roof conditions, dimensions, mounting requirements, plumbing and booster compatibility rather than brand alone.
Which Envirosun THX300/40 Variant Do I Need?
Envirosun currently publishes both electric and gas-boosted THX300/40 variants. The solar storage and two-collector closed-circuit layout remain similar, but the backup heating method and associated installation requirements differ.
| Feature | THX300/40Se | THX300/40Sg |
|---|---|---|
| Storage Capacity | 304L | 304L |
| Solar Collectors | 2 × E20HS | 2 × E20HS |
| Solar Circuit | Closed circuit | Closed circuit |
| Boost Type | Electric | Gas |
| Electric Booster | 2.4kW | Not applicable |
| Electric Boost Capacity | 140L | Not applicable |
| Gas Boost Rate | Not applicable | Up to 26L/min |
| Gas Heat Output | Not applicable | 42kW |
| Best Suited To | Properties suited to electric backup heating | Properties with suitable gas supply and gas boosting requirements |
The existing services at the property are an important part of variant selection. Changing booster type may require additional electrical, plumbing or gas work and should not be assumed to be a like-for-like change.
How Efficient Is the Envirosun THX300/40?
The THX300/40 uses solar energy as its primary heat source whenever useful solar input is available, with the selected electric or gas booster supporting the system when solar contribution alone does not meet household demand.
Actual purchased-energy use depends on roof orientation, shading, weather, seasonal conditions, household hot water consumption, incoming water temperature and how frequently boosting is required. A single running-cost figure therefore cannot accurately represent every THX300/40 installation.
The system is also listed by Envirosun as Clean Energy Regulator accredited and STC eligible where the applicable scheme requirements are met. The number and financial value of STCs depends on installation date and location, so the current benefit should be reflected through live pricing rather than permanently stated in the page copy.
THX300/40 Closed Circuit vs Standard TS300/40 Solar
| Feature | THX300/40 | TS300/40 |
|---|---|---|
| Storage Capacity | 304L | 304L |
| Collector Quantity | 2 × E20HS | 2 × E20HS |
| Installation Type | Roof-mounted thermosiphon | Roof-mounted thermosiphon |
| Solar Circuit | Indirect closed circuit | Open circuit |
| Freeze Protection | THX configuration specifically designed for frost-prone areas | Not the dedicated frost-prone configuration |
| Collector Water Exposure | Household water does not circulate directly through the collector circuit | Household water circulates through the open solar circuit |
| Main Reason to Choose | Closed-circuit freeze and fouling protection | Simpler open-circuit thermosiphon arrangement where suitable |
The THX300/40 is not automatically necessary for every Brisbane or Gold Coast property. Where frost and water-quality conditions do not require the closed-circuit configuration, a standard open-circuit system may also be worth comparing. Where those protections matter, the THX design becomes a meaningful technical difference rather than simply a marketing feature.
COMMON QUESTIONS
Envirosun THX300/40 Installation FAQs
How much does Envirosun THX300/40 installation cost?
Current supplied-and-installed pricing is shown in the live product selector above. Final cost depends on roof access, lifting requirements, mounting conditions, existing plumbing, booster type, valves, relocation and any non-standard installation work.
Can JR install the Envirosun THX300/40 in Brisbane?
Yes. JR supplies and installs the THX300/40 across eligible Brisbane service areas where the roof, access, plumbing and selected booster configuration meet the installation requirements.
Can JR install the Envirosun THX300/40 on the Gold Coast?
Yes. THX300/40 installation is available across eligible Gold Coast service areas subject to suitable roof space, structural conditions, access, plumbing and booster services.
Is the Envirosun THX300/40 a 300L system?
It belongs to Envirosun's THX300 product family, but the current manufacturer specification lists nominal storage capacity at 304L.
How many solar collectors does the THX300/40 use?
The current THX300/40 specification uses two E20HS flat-plate collectors. Each collector is approximately 1,235 × 2,000mm.
What makes the THX different from a normal Envirosun TS system?
The THX uses an indirect closed solar circuit. Envirosun positions this configuration for greater freeze protection and collector-fouling protection than its standard open-circuit thermosiphon system.
Is the THX300/40 suitable for frost-prone areas?
Yes. Envirosun specifically identifies THX closed-circuit models as the thermosiphon systems suitable and warranted for frost-prone applications, subject to the manufacturer's installation and warranty requirements.
Does the THX300/40 need a circulation pump?
No active solar circulation pump is required for normal thermosiphon operation. Heat transfer through the roof-mounted solar circuit occurs through natural circulation.
Can I choose electric or gas boosting?
Envirosun publishes both electric and gas-boosted THX300/40 configurations. The appropriate version depends on the services at the property and the installation requirements.
Can the THX300/40 replace another brand of solar hot water system?
Potentially, yes. Roof space, mounting conditions, system footprint, pipework, access and booster compatibility need to be checked rather than relying on brand or nominal storage size alone.
Can the THX300/40 replace a ground-mounted electric or heat pump system?
It can on a suitable property, but the conversion is more involved because the new tank and collectors are installed on the roof. New or altered roof mounting, plumbing and booster services may be required.
What happens if my roof does not suit the THX300/40?
A different solar layout or another hot water technology may be more appropriate. An active split system keeps the tank at ground level, while a heat pump avoids roof-mounted solar collectors entirely.
Envirosun THX300/40 Warranty and Maintenance
Manufacturer Warranty
Envirosun currently publishes a 10-year product warranty and 2-year labour warranty for qualifying residential original owner-occupiers for eligible systems purchased from 26 June 2026, subject to the manufacturer's warranty terms, exclusions and geographic conditions.
JR Lifetime Warranty Eligibility
The current JR THX300/40 product listing identifies the system as Lifetime Warranty eligible. JR warranty coverage is separate from Envirosun's manufacturer warranty and remains subject to JR's applicable servicing and warranty conditions.
Ongoing Maintenance
The roof-mounted tank, collectors, closed solar circuit, valves, booster components and associated plumbing should remain accessible for servicing and be maintained in accordance with Envirosun's current requirements.
Why Choose JR Gas & Water for Envirosun THX300/40 Installation?
Roof-mounted solar hot water is installation-dependent. A technically suitable product still needs the right roof position, safe access, correct mounting, suitable plumbing and a properly configured booster to produce a good long-term result.
JR Gas & Water has completed more than 10,000 hot water installations across South East Queensland and provides licensed hot water installation across Brisbane, the Gold Coast and surrounding service areas. JR's product and installation packages are designed to make straightforward replacements easier to select online while still providing a quote pathway for unusual or site-dependent work.
With the THX300/40, the focus is on whether the property genuinely benefits from a closed-circuit roof-mounted solar system and whether the roof and services can support the installation correctly.
COMPARE YOUR OPTIONS
Compare Solar Hot Water Systems & Installation Options
Compare roof-mounted thermosiphon solar, active split solar and other hot water systems before choosing the final replacement. Roof suitability, household demand, available services and installation complexity can all influence which system makes the most sense.
READY TO INSTALL
Install the Envirosun THX300/40 With JR Gas & Water
The Envirosun THX300/40 is a 304L roof-mounted solar system that combines two E20HS collectors with Envirosun's closed-circuit thermosiphon design. Its key difference from a standard open-circuit solar system is the additional protection the indirect solar circuit provides against freezing and collector fouling.
The main installation checks are roof structure, usable roof space, solar exposure, safe access, lifting requirements, plumbing and the selected electric or gas booster. Where the property fits JR's online installation conditions, choose the appropriate package through the live product selector above. More complex replacements, relocations or technology conversions can use JR's quote pathway.
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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
Brand - Envirosun
Model Number - THX300/40
Volume - 300L
Width - 2150mm
Height - 650mm
Manufactured In -
Cylinder/ Heat Exchange Material - Stainless Steel
Cylinder/Heat-Exchange Warranty - 7 Years
Noise Level - NAdBa
Dry Weight - 59kg
Energy Source - Solar
Wifi Controller Built in or Compatible -
Built In Timer - No
LED/LCD Status Indicator -
Coefficient of Performance (COP) -
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.
JR GAS & WATER INSTALLER ASSESSMENT
Our Installer Verdict
This is the part of the product page we consider most important. It is not based on manufacturer marketing or homeowner-facing specifications. This is our own assessment of what the product is actually like for our team to install, commission, service and support.
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