The EHS Flex 7kW Electric System Boiler is a compact, range-rateable heat-only electric boiler for wet central heating or underfloor heating systems. It connects directly into existing radiator or UFH pipework in place of a gas system boiler, needs no flue and no gas supply, and heats the home purely from a standard single-phase electricity supply.
As part of EHS's current Flex platform, this model can have its maximum heating output configured by a qualified installer to match the exact heat loss of the property, rather than needing a different fixed-output boiler for every size of home. Paired with a separate unvented indirect cylinder, it can also support mains-pressure domestic hot water on smaller, lower-demand properties.
Range-Rated
Configurable down to 2.3kW
5 Yrs
Manufacturer warranty*
How it fits your system
The Flex 7kW connects to existing radiator or underfloor heating flow-and-return pipework in place of a gas system boiler, with no need to resize radiators or re-pipe the property. It is heating-only — domestic hot water requires a separate cylinder connected to the same circuit.
Because it is range-rateable, a qualified installer can set its maximum output anywhere between roughly 2.3kW and 7kW to closely match the property's heat loss, reducing short-cycling and wasted running costs compared to a fixed-output boiler that's oversized for the job.
Installation requirements
Range rating must only be carried out by a qualified electrical installer via EHS's online installer support portal — the cable size and circuit protection must always match the maximum output the boiler could deliver, not the de-rated setting.
An automatic bypass valve (ABV) and an external inline magnetic filter must be fitted on every installation; omitting either can trigger boiler fault codes and will affect the manufacturer's warranty. The boiler must be filled and pressure-tested before any electrical connection is made.
Range-rateable output
Maximum heating power can be configured by a qualified installer from roughly 2.3kW up to the full 7kW, letting one boiler cover a wider range of heat loss calculations.
Integrated pump & expansion vessel
A circulating pump and 5-litre expansion vessel are built into the casing, along with pressure and flow sensors, reducing the ancillary parts an installer needs to source.
No flue or gas supply
Fully electric operation removes combustion risk entirely — no carbon monoxide exposure and far more flexibility over where the unit can be sited.
Touch-screen control panel
Front-mounted digital display with clear on/off, mode, and temperature controls, plus a boiler lock to prevent unauthorised or accidental adjustment.
Built-in frost protection
Two-stage frost protection automatically runs the pump and heat exchanger if the internal temperature drops too low, protecting the system when power remains connected.
Compact, wall-mounted design
At 585 × 380 × 235mm and around 19kg net, the unit mounts on six fixing points and needs only 100mm clearance on each side for servicing.
Boiler Details
Manufacturer
Electric Heating Systems Ltd (EHS)
Model
7kW EHS Flex System Boiler
SKU / Part Code
ALS1-1PSY-7F
Product Type
Electric system boiler — heating only, range-rateable
Heating Power
7 kW maximum, single-phase (configurable from 2.3kW)
Hot Water Power
N/A — heating only; requires a separate indirect cylinder for DHW
Electrical & Installation
Electrical Supply
230V AC, single-phase, 50Hz
Rated Current @ Full Output
26 A
Minimum Cable Size
6 mm² (3-core)
Range Rating
Field-configurable in steps from 2.3kW to 7kW via EHS installer portal — qualified electrician only
Flue Requirement
None — no flue or gas connection needed
Plumbing & Physical
Flow & Return Connection
G3/4" male thread
Operating Water Pressure
1–3 bar
Expansion Vessel Capacity
5 litres, internal
Heating Flow Temperature Range
30–80°C (radiators) / 30–60°C (underfloor heating)
Servicing & Support
Annual Service
Recommended and required to maintain full warranty cover
Required Ancillaries
Automatic bypass valve and external inline magnetic filter (both mandatory for warranty)
Warranty*
5 years when registered with EHS within 30 days of installation (2 years parts & labour, plus 3 years parts only); unregistered installs default to 1 year parts & labour only
Frequently Asked Questions
Does the EHS Flex 7kW boiler provide hot water on its own?
No. This is a heating-only system boiler with no built-in hot water power. Domestic hot water needs a separate indirect cylinder connected to the same heating circuit.
What does 'range-rateable' actually mean for this boiler?
The boiler's maximum heating output can be configured by a qualified installer to a lower setting than its full 7kW, so it can be matched more precisely to a property's calculated heat loss. This is done through EHS's online installer support portal and must only be carried out by a qualified electrical installer.
Do I need to change my radiators or pipework to fit this boiler?
No. It connects to existing radiator or underfloor heating flow-and-return pipework via G3/4" connections in place of a gas system boiler, so current radiators or UFH loops don't need to be replaced.
What electrical supply does the Flex 7kW need?
A 230V single-phase supply with a minimum 32A MCB/RCBO and 6mm² cable at full 7kW output. An electrician should always carry out a load and voltage test before installation to confirm the property's supply is adequate.
Is a flue or gas connection required?
No. As a fully electric boiler it needs no flue and no gas supply, which removes carbon monoxide risk and gives much greater flexibility over where it can be sited in the property.
What do I need to do to get the full 5-year warranty?
The boiler must be registered with EHS within 30 days of installation, fitted exactly per the manufacturer's installation manual — including an automatic bypass valve and external magnetic filter — and serviced annually by a qualified engineer. Missing the registration window resets cover to 1 year parts and labour only.
