The EHC 10kW SlimJim Electric Flow Boiler & 150L Indirect Unvented Cylinder pairs a compact, wall-mounted electric flow boiler with a 150-litre stainless steel unvented cylinder to deliver fully electric central heating and mains-pressure hot water without a flue, gas supply, or annual gas safety inspection. The SlimJim boiler is 100% efficient and uses a fully insulated stainless steel heat exchanger with a Run-Dry Water Level Sensor to protect against low system water. Indirect plumbing means the boiler heats the cylinder via an internal coil, keeping the immersion heater as backup only. Both units are designed to maximise cupboard and plant room space, with the boiler measuring just 912mmmm wide.
5yr / 25yr
Boiler / Cylinder Warranty
Installation & electrical requirements
This is a 50A protection boiler circuit at the 10kW output and must be installed by a qualified electrician in accordance with BS 7671 IEE Wiring Regulations. A load check must be carried out before installation to confirm the property’s incoming supply and existing electrical load can support the boiler. The unvented cylinder must be installed by a G3 competent person and the system commissioned in line with Building Regulations Part G3 (England & Wales), Scottish Technical Standard P3, or NI Building Regulations Part P as applicable.
System design note
An automatic bypass or a locked-open bypass radiator (minimum 600mm x 600mm single convector, or 2500 Btu equivalent) must be included in the heating circuit, in the same zone as the room thermostat. A magnetic filter should be fitted on the return pipework ahead of the circulation pump and cleaned annually — failure to do so may allow debris to contaminate the boiler and will affect the warranty.
Indirect vs. direct: which cylinder do I need?
This package uses an indirect cylinder, which is heated via an internal coil connected to the SlimJim boiler’s central heating circuit, with the built-in immersion heater providing backup only. This is the correct configuration when the boiler is also expected to provide domestic hot water alongside space heating.
100% Efficient Heat Exchanger
The stainless steel heat exchanger converts electrical input directly into heat with no flue losses, and is fully insulated to minimise standing heat loss in the boiler casing.
Run-Dry Protection
A Run-Dry Water Level Sensor shuts the boiler down if system water is lost, preventing the heat exchanger from firing dry and suffering damage.
Selectable Power Staging
The boiler’s output can be dip-switch configured in three stages, allowing the installer to match power draw to the property’s heat loss calculation and electrical supply capacity.
Compact Wall-Mounted Footprint
At just 912mm (H) x 203mm (W) x 172mm (D), the boiler is designed to maximise cupboard and plant room space where a conventional boiler or cylinder cupboard would otherwise be too small.
150L Stainless Steel Cylinder
The 150-litre duplex stainless steel unvented cylinder is TIG-welded and factory pressure-tested, providing mains-pressure hot water with a 25-year cylinder guarantee.
Volt-Free or 240V Control Signalling
External controls can be wired as volt-free or 240V switched signals, giving installers flexibility to integrate with S-Plan zoning, programmers, and room thermostats.
SlimJim Boiler Specification
| Boiler Model |
EHCSJIM10KW |
| Rated Output |
10kW, single-phase |
| Electrical Supply |
230–240V, 50Hz, 1-phase |
| Circuit Protection Required |
50A (per manufacturer boiler protection table) |
| Overall Dimensions (H x W x D) |
912mm (H) x 203mm (W) x 172mm (D) |
| Weight |
approx. 25kg |
| Flow Temperature Range |
30–80°C (factory set 80°C) |
| Efficiency |
100% |
| Heat Exchanger |
Fully insulated stainless steel |
| Safety Devices |
WT3 thermal cut-out, Run-Dry water level sensor, electronic fault diagnostics |
| Control Signalling |
Volt-free or 240V (selectable via control board dip switch) |
| Boiler Warranty |
5 years parts and labour |
Cylinder Specification
| Cylinder Model |
NIND150L |
| Cylinder Type |
Indirect Unvented |
| Capacity |
150 litres |
| Height |
1060mm |
| Diameter |
510mm |
| Construction |
Duplex stainless steel, TIG welded |
| Insulation |
CFC- and HCFC-free injected polyurethane foam |
| Max. Operating Pressure |
3.0 bar |
| Factory Pressure Test |
15 bar |
| Immersion Heater (backup) |
3kW, Incoloy sheathed element |
| Cylinder Guarantee |
25-year stainless steel vessel guarantee (2 years parts & labour on components) |
| Building Regulation Compliance |
G3 (England & Wales) / Technical Standard P3 (Scotland) / Part P (Northern Ireland) |
| Component |
Detail |
| SlimJim Electric Flow Boiler |
10kW single-phase, 912mm (H) x 203mm (W) x 172mm (D) |
| 150L Unvented Cylinder |
Indirect stainless steel, coil-heated by boiler |
| Circulation Pump |
Pre-fitted to heating circuit |
| Automatic Bypass Valve |
Included for zoned system protection |
| Temperature & Pressure Relief Valve |
Fitted to cylinder for overpressure protection |
| Expansion Vessel |
Sized to system volume |
| Auto Air Vent |
Fitted per manufacturer instructions (not directly above boiler) |
Does this boiler need a flue or gas supply?
No. The SlimJim is a fully electric flow boiler with no flue, no gas connection, and no requirement for an annual gas safety inspection.
What electrical protection does the boiler need?
The 10kW SlimJim requires 50A circuit protection per the manufacturer’s boiler protection table. A qualified electrician must carry out a load check before installation to confirm the property’s supply can support this.
Is the 150L cylinder indirect or direct?
This package includes the indirect version. The cylinder is heated via an internal coil connected to the boiler’s heating circuit, with its 3kW immersion element providing backup only.
Can the boiler run underfloor heating as well as radiators?
Yes. The SlimJim range can be configured for radiator circuits, underfloor heating circuits, or a combination via S-Plan zoning, subject to correct system design and an automatic bypass being fitted.
Does the cylinder need annual servicing?
The cylinder itself has low ongoing maintenance requirements, but the magnetic filter fitted to the heating circuit should be cleaned annually, and the expansion vessel and safety valves should be checked periodically by a qualified installer.
What warranty is provided?
The SlimJim boiler carries a 5-year parts and labour warranty. The cylinder’s stainless steel vessel is guaranteed for 25 years, with a 2-year parts and labour warranty on cylinder components, both subject to correct commissioning and registration.
