EHC Comet 2/4/6/8kW System Electric Boiler | EHC.CS8KW | 5-Year Warranty

Description

The EHC Comet 2/4/6/8kW System Electric Boiler (EHC.CS8KW) is the entry-power model in the Comet Standard System range, built on over 21 years of EHC electric heating expertise. It replaces a gas or oil system boiler where no flue is available, delivering central heating and domestic hot water via an S-Plan configuration from a single, compact wall-mounted unit.

This model runs on a single-phase 230V supply with four selectable output settings — 2kW, 4kW, 6kW or 8kW — configured on-site to match the property’s heat loss and available electrical capacity. The pump, expansion vessel, automatic air vent, auto-bypass and high-current thermal cut-out are all factory-fitted inside the casing, so there is no external plumbing or pipework to install.

2–8 kW

Selectable Output

230V 1N~

Single Phase Supply

41 dB

Quiet Operation

20.5 kg

Boiler Weight

20–85°C

Flow Temperature

5 Years

Manufacturer Warranty

Important Safety Information

This boiler must be installed by a qualified electrician in accordance with BS 7671 Wiring Regulations. A 30mA RCD, dedicated local isolation and an in-line magnetic filter are all mandatory — failure to fit a magnetic filter to this boiler will invalidate the manufacturer’s warranty.

Please Note

A load check of the property’s incoming electrical supply should be carried out before installation, as upgrading the main fuse may be required at higher output settings. Minimum supply cable cross-section must be calculated by a qualified electrician in line with BS 7671, using the load current values in the specification table below.

Key Features

Flexible Multi-Output Technology

Four selectable outputs (2, 4, 6 or 8kW) let installers range-rate the boiler on site to match the exact heat loss of the property.

Six-Stage Modulation

A stainless steel heat exchanger with six-stage heating modulates output in real time, reducing electricity consumption and running costs.

Virtually Silent Operation

Rated at just 41dB, the Comet Standard operates quietly enough for airing cupboards, kitchens and utility rooms.

Underfloor Heating Compatible

Adjustable flow temperature from 20–85°C makes it equally suited to underfloor heating and traditional radiator systems.

Compact Wall-Mounted Design

All core components — pump, expansion vessel, auto-air vent and auto-bypass — are built into a single 716 x 316 x 235mm casing for a one-person lift and install.

Trusted EHC Technology & Support

Backed by 21+ years of UK electric heating manufacture and a 5-year manufacturer’s warranty (registration required).

Specification

Performance

Rated Power Output

2 / 4 / 6 / 8 kW

Rated Voltage

230V 1N~ (single phase)

Outlet Flow Temperature Range

20–85°C

Maximum Temperature

100°C

Sound Level

41 dB

Minimum System Flow Rate

3.5 l/min

Electrical Data

MCB Rating

16 / 20 / 32 / 40 A

Load Current

8.7 / 17.4 / 26.1 / 34.8 A

Minimum Supply Cable Cross-Section*

2.5 / 4 / 6 mm²

Maximum Supply Cable Cross-Section

16 mm²

Maximum Allowed Network Impedance

0.27 / 0.17 / 0.15 Ω

Hydraulics & Build

Boiler Connections

G 3/4" (internal thread)

Maximum System Pressure

0.3 MPa (3 bar)

Minimum System Pressure

0.05 MPa (0.5 bar)

Built-In Expansion Vessel

5 litres, 1.5 bar precharge

Safety Class (Ingress Protection)

IP 22

Heat Exchanger

Stainless steel

Dimensions & Warranty

Dimensions (H x W x D)

716 x 316 x 235 mm

Weight

~20.5 kg

Manufacturer Warranty

5 years (registration required, T&Cs apply)

Good to Know

*Minimum cable cross-sections are the manufacturer’s stated minimums only. The cable size for your installation must be calculated separately by a qualified electrician in accordance with BS 7671, accounting for cable type, routing and supply voltage deviation.

Frequently Asked Questions

Can this boiler provide hot water as well as heating?

Yes. The EHC.CS8KW can be installed for heating only, or for combined heating and domestic hot water when wired in an ‘S’ Plan configuration alongside a compatible hot water cylinder and twin-channel control.

Do I need to choose one fixed output, or can it be changed later?

The boiler ships with all four output settings available. The installer configures the required output (2, 4, 6 or 8kW) during commissioning via the DIP switches and control panel software — it is not locked to a single kW rating at the factory.

What electrical supply does this model need?

The 2/4/6/8kW model runs on a single-phase 230V supply. Required MCB rating rises with the selected output (from 16A at 2kW up to 40A at 8kW), so a qualified electrician should confirm the property’s available supply capacity before installation.

Is a magnetic filter really mandatory?

Yes. A magnetic filter must be fitted to the return of this boiler. This is a manufacturer warranty condition, not just best practice — installing without one will void the warranty regardless of any other fault.

Is this boiler suitable for underfloor heating?

Yes. The adjustable flow temperature range of 20–85°C covers both low-temperature underfloor systems and standard radiator circuits, and the boiler is compatible with wet underfloor heating installations.

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Room Dimensions

Length (in m):

Width (in m):

Height (in m):

Room Type

Living Room

Bedroom

Kitchen

Bathroom

Conservatory

Hallway

Glazing Type

Single Glazed

Double Glazed

Triple Glazed

External Walls

0 Wall

1 Wall

2 Walls

3 Walls

4 Walls

Insulation Level

Poor

Average

Good (New Build)

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