The Joule Invacyl Unvented 300L Indirect Cylinder Standard is a high-capacity unvented hot water cylinder designed for reliable domestic and commercial hot water storage. With an actual storage capacity of 295.3 litres, it is suited to installations with larger hot water demands, including larger residential properties, utility rooms and plant rooms.
The cylinder uses a 316L stainless steel heating coil rated at 17.26kW with a 0.79m² surface area, supporting indirect heating from a boiler, heat pump or solar thermal system. Manufactured using LDX 2101 cylinder material with a coated mild steel outer casing and dense PU foam insulation, the unit is designed to provide dependable hot water storage while helping to retain heat.
295.3L Actual Capacity
Indirect Unvented
316L Stainless Steel Coil
25-Year Warranty
Applications & suitability
Large Residential Properties
The 295.3L actual capacity provides substantial hot water storage for homes with higher hot water demand.
Commercial Applications
Suitable for commercial buildings and small businesses requiring consistent mains-pressure hot water.
Multiple Heat Sources
The indirect coil supports primary heating from boilers, heat pumps or solar thermal systems.
Plant & Utility Rooms
A high-capacity cylinder solution for utility rooms, plant rooms, renovation and new-build projects.
Key specifications
| Product Model |
Joule Invacyl Unvented 300L Indirect Cylinder Standard |
| Product Type |
Hot Water Cylinder (Indirect Unvented) |
| Actual Capacity |
295.3 L |
| Maximum Mains Water Pressure |
10 bar |
| Operating Pressure |
7 bar |
| Operating Temperature |
60 °C |
| Safety Valve Temperature |
90 °C |
| Unit Weight Empty |
60 kg |
| Unit Weight Full |
355 kg |
| Cylinder Material |
LDX 2101 |
| Outer Casing |
Coated Mild Steel |
| Thermal Insulation |
Dense PU Foam |
| Foam Thickness |
0 |
| Heat Loss |
2.04 kW/24h |
| Coil Material |
316L Stainless Steel |
| Coil 1 Rating |
17.26 kW |
| Coil 1 Surface Area |
0.79 m² |
| Coil 1 Maximum Primary Pressure |
6 bar |
| Coil 1 Resistance |
0.2 bar |
| Immersion Specification |
3 kW @ 230 V |
| No. of Immersions |
1 |
| No. of Heat Exchangers |
1 |
| Tested to Standard |
BS EN 12897:2016 |
| Warranty Terms |
25 Years |
Installation & compatibility
The Joule Invacyl Unvented 300L Indirect Cylinder Standard is designed for unvented mains-pressure hot water systems. Its indirect 316L stainless steel coil can be used with boilers, heat pumps or solar thermal systems as the primary heat source, while the 3kW immersion specification provides additional heating capability.
Design & performance benefits
High-Capacity Storage
The 295.3L actual capacity provides substantial stored hot water for larger domestic and commercial requirements.
316L Stainless Steel Coil
A 316L stainless steel coil provides indirect heating with a 17.26kW rating and 0.79m² surface area.
Mains-Pressure Operation
Designed for unvented operation with a maximum mains water pressure of 10 bar and operating pressure of 7 bar.
Long-Term Warranty
Includes a 25-year warranty term for long-term product support and peace of mind.
Additional installation features
Robust Construction
LDX 2101 cylinder material is combined with a coated mild steel outer casing.
Dense PU Foam
Dense PU foam thermal insulation is specified to support heat retention, with a stated heat loss of 2.04 kW/24h.
Tested Standard
The cylinder is tested to BS EN 12897:2016.
Ideal for
The Joule Invacyl Unvented 300L Indirect Cylinder Standard is ideal for larger homes, commercial buildings, small businesses, renovation projects and new-build installations requiring high-capacity mains-pressure hot water storage. With its 295.3L actual capacity, 316L stainless steel indirect coil, 3kW immersion specification and 25-year warranty, it provides a substantial hot water storage solution for systems using boilers, heat pumps or solar thermal as the primary heat source.
At GetPlumb, we strive to provide reliable and cost-effective delivery options to our customers. Please review our shipping policy below.
🆓 Free Local Delivery (Orders £100 & above)
We offer FREE delivery on orders £100 or more
for selected local areas.
Eligible Postcodes Include:
- RG*
- SL*
- OX10*, OX11*, OX49*
- HP1*, HP3*, HP8*, HP9*, HP10*, HP11*, HP12*, HP13*, HP14*
- WD*, HA*, UB*, TW*, KT*
- W1* – W9*
- NW*, SW*
Delivery Time: 2–4 working days
Shipping Cost: £0.00
📦 Standard Shipping (Weight-Based Rates)
For orders that do not qualify for free delivery, standard
shipping rates apply based on total cart weight.
- For cart weight between 0–2 kg, the shipping cost is £4.50 with a delivery time of 2–4 working days.
- For cart weight between 2–24 kg, the shipping cost is £9.99 with a delivery time of 2–4 working days.
- For cart weight between 24 kg and above, the shipping cost is £60 with a delivery time of 2–4 working days.
🧱 Block Salt (Harvey’s) – Unit-Based Shipping
This rate applies only to Harvey’s block salt products.
- £7.99 is charged for every 3 items.
- The charge increases by £7.99 for each additional set of 3 items.
Examples:
- 1–3 items → £7.99
- 4–6 items → £15.98
- 7–9 items → £23.97
Delivery Time: 2–4 working days
📏 Large / Long Items (Length-Based Shipping)
For oversized items where the product length is 1.5 metres or more:
Conditions:
- Product length ≥ 1.5 m
- Cart weight ≤ 40 kg
Shipping Cost: £18.00 (flat rate)
Delivery Time: 2–4 working days
Collection from Store
Customers can also choose to collect their order from our store in
Reading, UK, at no additional charge. For any questions regarding shipping, please contact our support team at online@getplumb.co.uk.
