EHC 12kW Slimjim Electric Flow Boiler & 150L Direct Cylinder
FREE Express Delivery (1-3 days) in UK Mainland on most orders*
Excluding: Solar Panels (£170 delivery / free above £2,500), Batteries (£39 delivery), Small Items (£4.95/5.95 delivery / free above £500)
Contact Us to check for Next Working Day Delivery or Same-day Delivery options
Contact Us for Click & Collect options
Custom quote available on request
*See checkout or shipping policy for full details
Payment options
Do you have a question
about this product?
One of our expert advisors will be happy to help you!
Contact Us
The EHC 12kW SlimJim Electric Flow Boiler & 150L Direct Cylinder Package (EHCSJ12/150) pairs the compact SlimJim electric flow boiler with a 150-litre Neptune Direct Unvented Stainless Steel Cylinder and matched Boiler Pack controls. The Direct cylinder is heated entirely by its own twin 3kW immersion elements, so the boiler is dedicated solely to space heating — a simple, self-contained configuration for properties with lower or independent hot water demand.
Qualified Installation & Load Check Required
This boiler must be installed and electrically connected by a qualified electrician in accordance with BS7671. A load check must be carried out before installation, as the boiler draws 50.0A and the property's incoming supply may need upgrading. The supply must be protected at the meter position with a 30mA double-pole RCD (minimum 3mm contact separation) and a suitably rated MCB. A magnetic filter must be fitted to the return pipework before the circulation pump — failure to clean it annually may result in boiler or system failure and will affect warranty cover.
Boiler Dedicated to Space Heating
Because the Direct cylinder heats independently via its own twin immersion elements, the SlimJim boiler in this package can be commissioned for heating only, simplifying control wiring where a separate, self-contained hot water solution is preferred. This also means no primary coil pipework is needed between boiler and cylinder.
Direct Cylinder Has No Boiler-Heated Coil
This 150L Direct cylinder has no internal coil connected to the boiler's primary circuit — all hot water is generated by the two 3kW immersion elements. Recovery time will be slower than an equivalent-capacity Indirect cylinder. Where a property has high or frequent hot water demand, consider one of EHC's Indirect or Pre-Plumbed Indirect SlimJim packages instead.
Compact Flow Boiler Footprint
At 912 x 203 x 172mm, the SlimJim is designed to maximise cupboard space compared with bulkier system boiler designs, while remaining fully controllable via its front panel.
Simple, Self-Contained Hot Water
With hot water generated entirely by the cylinder's own immersion elements, the system requires no primary coil plumbing between boiler and cylinder, simplifying pipework for heating-only boiler installations.
Three-Stage Output Control
On-board dip switches allow the boiler's rated output to be staged down on site, giving some flexibility to match the installed heat load without needing a different chassis.
High-Current Safety Cut-Out
A dedicated WT3 safety thermal cut-out disconnects the boiler if the internal temperature reaches approximately 100°C, protecting the heat exchanger from failure.
Twin Immersion Elements
The 150L Direct cylinder's two 3kW Incoloy elements allow for boost and economy heating modes, giving flexibility over how quickly and how much hot water is heated at any one time.
No Flue, No Combustion Byproducts
As a fully electric flow boiler, the SlimJim requires no flue, no gas supply, and no annual gas safety check, simplifying installation versus a fossil-fuel system boiler.
| Boiler — 12kW SlimJim (General) | |
| Model / MPN | EHCSJ12/150 |
| Boiler chassis | SlimJim Electric Flow Boiler |
| Boiler dimensions (H x W x D) | 912 x 203 x 172mm |
| Boiler weight | ≈11kg |
| Boiler connections | 22mm compression (flow top, return bottom) |
| Safety class | IP22 |
| Outflow water temperature range | 30 – 80°C |
| Max. water temperature | 100°C |
| Overheat protection cut-out | 100°C |
| Max. system pressure | 3 bar |
| Min. system pressure | 0.5 bar |
| Boiler — 12kW SlimJim (Electrical) | |
| Electrical supply | 240V 1ph 50Hz |
| Load current | 50.0A |
| Minimum permitted cable diameter* | 10mm² |
| Recommended protection (MCB) | 63A |
| Max. allowed network impedance | 0.24Ω |
| Heat output | 40,946 BTU/h |
| ErP rating | D |
| Cylinder — 150L Neptune Direct | |
| Cylinder capacity | 150 litres |
| Cased height | 1060mm |
| Cased diameter | 510mm |
| Construction | Duplex stainless steel, TIG welded |
| Factory pressure test | 15 bar |
| Insulation | CFC- and HCFC-free polyurethane foam |
| Regulatory status | Controlled service – England & Wales Building Reg. G3 / Scotland Technical Standard P3 / N. Ireland Building Reg. Part F |
| Max. inlet mains water pressure | 12 bar |
| Operating pressure | 3.0 bar |
| Expansion vessel charge pressure | 3.0 bar |
| Expansion valve opening pressure | 6.0 bar |
| Max. operating pressure | 7.0 bar |
| T&P relief valve opening | 7.0 bar |
| Immersion elements | 2 x 3kW, 240V, Incoloy (upper boost / lower economy) |
| Boiler Pack (1) — Included Components | |
| Controls | 24/7 programmer, room thermostat, DHW programmer |
| Circulation | High-efficiency circulating pump, lockshield pump valves |
| System kit | 8-litre expansion (sealed system) kit, auto air vent |
| Protection | Magnetic filter |
| Warranty | |
| Boiler warranty | 2 years parts & labour, subject to registration and annual servicing |
| Cylinder warranty | 2 years parts & labour from commissioning, subject to registration |
| Stainless steel inner vessel | 25-year guarantee (domestic installations) |
*Minimum permitted cable size; actual installation cable size must be calculated by a qualified electrician per BS7671, accounting for cable type and installation method.
Do you have a question
about this product?
One of our expert advisors will be happy to help you!
Contact Us