JAB DUC IE Compact 120L Indirect Internal Expansion Unvented Hot Water Cylinder
Product Ref: DIEC120i
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JAB DUC IE Compact 120L Indirect Internal Expansion Unvented Hot Water Cylinder Downloadable Documents
JAB DUC IE Compact 120L Indirect Internal Expansion Unvented Hot Water Cylinder
The JAB DUC IE 120L Indirect Internal Expansion Unvented Cylinder is a compact, high-performance hot water storage system designed for modern domestic applications where space, efficiency, and reliability are key.
Constructed from high-grade duplex stainless steel, this 120-litre cylinder offers excellent corrosion resistance and long-term durability. It's engineered for mains-pressure hot water delivery. Providing powerful flow rates for showers, taps, appliances without the need for a cold-water storage tank.
The Internal expansion design eliminates the requirement for an external expansion vessel, simplifying installation and saving valuable space - making it ideal for small homes, apartments, and en-suite systems. The indirect coil connection allows the unit to be heated by a boiler or renewable heat source, with an immersion heater connection for backup heating.
Applications
- Domestic properties requiring mains-pressure hot water
- Homes using a system or regular boiler (not combi boilers)
- Installations where Space is limited and an external expansion vessel is undesirable
- Upgrading from vented systems (loft tank) to modern, sealed unvented systems
- Properties needing energy-efficient, corrosion-resistant stainless steel cylinders
- Full compliance with UK Building Regulations G3 (installation by G3-qualified engineer required)
- Typical use: 1-2 Bedroom homes with 1 bathroom.
Key Features & Benefits
- 120-Litre Capacity - 120-litre stainless steel unvented cylinder
- Stainless steel construction for long life and corrosion resistance
- Indirect coil for use with boiler systems
- Internal expansion system - no separate vessel required
- Factory-Fitted insulation for reduced heat loss
- Compact Design ideal for tight spaces
- Suitable for use with system and regular boilers
- Fully compliant with G3 Building Regulations
- Space Saving Installation - Built-in expansion chamber simplifies setup
- Strong Mains-Pressure Performance- Consistent flow for showers and multiple outlets
- Reduced Installation Time - Fewer components and fittings required
- Energy Efficient - Excellent insulation minimises standing heat loss
- Low Maintenance - Minimal servicing required compared to external systems
- Renewable Ready - Compatible with heat pumps and solar thermal (check model suitability)
- 25-Year Warranty - Including One Year On-Site Warranty
- U.K. Manufactured
How it works
- Colds Mains Feed: Water enters directly from the mains supply, ensuring high-pressure delivery throughout the home.
- Indirect Coil Heating: A boiler (or renewable source) transfers heat through the internal coil, warming the stored water
- Internal Expansion Control: As the water heats and expands, the built-in air gap inside the cylinder absorbs pressure changes - removing the need for an external expansion vessel
- Hot Water Storage: Heated water is stored in the insulated stainless steel cylinder, ready for on-demand use
- Backup Immersion Heating: The immersion heater provides secondary or off-peak heating when required
Specifications
| Product Code | DIEC120i |
| Nominal Capacity (L) | 120 |
| Height (mm) | 925 |
| Diameter Ø (mm) | 550 |
| Cold Inlet | 186 |
| Heating Flow | 180 |
| Return | 220 |
| Control Stat | 340 |
| Immersion | 270 |
| T+P Valve | 508 |
| ERP Energy Band | B |
| Standing Heat Loss (W) | 50 |
| Standing Heat Loss kWh/24h | 1.2 |
| Coil rating (kW) | 17.76 |
* Please note, the image is for visual purposes only and may be slightly different upon arrival
JAB DUC IE Compact 120L Indirect Internal Expansion Unvented Hot Water Cylinder Specification
- Product Code: HWS
- Guarantee: 25 Year Guarantee
JAB DUC IE Compact 120L Indirect Internal Expansion Unvented Hot Water Cylinder Delivery Information
Tanks:
The delivery of a tank can be confusing as each manufacturer offers a slightly different service and lead time. Please refer to our Delivery Information page. Standard tank deliveries are "kerbside" which means the tank will be delivered to the kerb only and not positioned further. Should you have specific delivery requirements or restrictions, please contact us to discuss.
Tanks Over 2500L – Articulated Lorry – Customer Offload:
These tanks will be delivered on an articulated vehicle (approximately 16.5m long x 2.6m wide x 3m high) which has no offloading on board, it is the customer's responsibility to offload the tank, which may require a telehandler / forklift. Curtain sided vehicles are also used, so please note that if there are obstacles or hanging branches on the road to the delivery site etc, the driver may refuse to drive the vehicle to the customer's location due to the possibility of damaging the vehicle. Please let us know if there are any obstructions before delivery, so we can arrange alternative transport.
18 Tonne Tail Lift HGV
This vehicle is the size of the largest bin lorries (for comparison) and is approximately 8.2m long x 2.6m wide x 4m high, often curtain sided so please note that if there are hanging branches etc, these vehicles will not attempt to drive down due to the possibility of damaging the vehicle and so it is recommended that a smaller vehicle is requested. Tanks will be lowered to the ground but not positioned as this is a kerbside delivery. If a smaller vehicle is required, please email us at sales@fueltankshop.co.uk quoting your order number and name.
HIAB Delivery
HIAB delivery is available but must be requested and there will be an additional cost for this service. If a HIAB delivery is required, please email us at sales@fueltankshop.co.uk quoting your order number and name, and we will come back to you with a price for this service.
Accessories:
Most accessories will be delivered within 1-3 working days (certain products and postcodes may take longer, please check the product page for update to date information). If you require them quicker, we can on occasions offer a next day service (please contact us to discuss). If the item(s) are out of stock, we will advise you of the expected lead time, and you will of course have the opportunity to cancel with a full refund.
JAB DUC IE Compact 120L Indirect Internal Expansion Unvented Hot Water Cylinder Returns Information
Customers may return items within 14 calendar days (as per our Terms & Conditions) - refer to section 7. **
All Items must be returned unused, refunds cannot be issued for used or previously installed items.
Please be aware that returning a tank can be complicated and expensive, so please check that you are ordering the correct item (we suggest checking the dimensions very carefully).
If you wish to return goods, please complete the form on this page to provide further information.
Once your request is approved, a valid Returns Authorisation Number (RAN) will be issued to initiate the returns process along with information on how & where to return your order along with any costs involved.
Please DO NOT return any goods without this authorisation. Goods cannot be accepted without this.
Returns are not accepted at our Minehead Office, please wait until we contact you before returning any goods.

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