The EHS Installer Kit (EHS-COMBIKIT251F) bundles every plumbing and control component an installer needs to complete a compliant EHS FLEX electric boiler installation in a single part number. It is built around the components EHS itself specifies as mandatory in the FLEX installation manual — an automatic bypass valve, an inline magnetic filter, and a WRAS-approved filling loop — alongside system chemicals, isolation valves, a Boiler Plus compliant programmable thermostat, and the flow restrictor needed to guarantee shower-temperature hot water from an EHS FLEX combi boiler. Fitting this kit alongside an EHS boiler also unlocks a 2-year extended warranty on top of the standard 5-year manufacturer's guarantee.
5 L/min
Caleffi flow restrictor
WRAS
Approved filling loop
BS 7593
Chemical treatment std.
Boiler Plus
Compliant thermostat
⚠ Mandatory Components for EHS Warranty Compliance
EHS state in the FLEX installation manual that failing to fit an automatic bypass valve can trigger repeated F6 error codes or a complete boiler shutdown, and will affect the warranty. An inline magnetic filter is also specified as mandatory on the heating return, and its omission similarly affects warranty cover. Both are included in this kit as standard.
⚠ Boiler Sold Separately
This is the installer kit only — it does not include the EHS FLEX electric boiler itself. It is designed to be fitted alongside any EHS FLEX combi or system boiler, including the EHS Primus 14000C Flex (ALC1-1PCO-14F). Confirm the correct EHS boiler model separately before ordering.
✔ Sentinel Magnetic Filter — Vortex 250
An inline Sentinel Vortex 250 magnetic filter fitted to the heating return protects the boiler's heat exchanger and pump from system debris. EHS specify a magnetic filter as a mandatory fitting on every installation, checked at each service interval.
✔ Sentinel X300 Cleaner & X100 Inhibitor
Sentinel X300 system cleaner flushes existing pipework free of sludge and debris to the 10% mains PPM standard EHS require under BS 7593, while Sentinel X100 inhibitor protects the system against corrosion and scale once commissioned — a condition of the EHS warranty.
✔ EPH Combi Pack 4 Thermostat
A wireless RF programmable thermostat and receiver, OpenTherm-ready and Boiler Plus compliant, giving the property a proper time-and-temperature control as required under Part L of the Building Regulations for combi boiler replacements.
✔ WRAS Approved Filling Loop
A WRAS-approved filling loop for safely pressurising the heating circuit without ever forming a permanent connection between mains water and the heating system, exactly as EHS's installation manual specifies.
✔ Automatic Bypass Valve (ABV)
The automatic bypass valve that EHS mark as mandatory on every FLEX installation. It opens progressively as TRVs close down, maintaining minimum flow through the boiler and preventing the F6 no-flow error.
✔ Isolation Valves & Caleffi Flow Restrictor
Four full-bore isolation valves (2× ½" and 2× ¾") for clean servicing access, plus a Caleffi 5 L/min flow restrictor — the exact flow rate EHS recommend to guarantee consistent shower-temperature hot water from a combi boiler regardless of incoming mains pressure.
Kit Contents
Part No.
EHS-COMBIKIT251F
Magnetic Filter
Sentinel Vortex 250
System Cleaner
Sentinel X300
System Inhibitor
Sentinel X100
Thermostat
EPH Combi Pack 4 — wireless RF, OpenTherm, Boiler Plus compliant
Filling Loop
WRAS approved
Bypass Valve
Automatic Bypass Valve (ABV) — mandatory per EHS specification
Isolation Valves
4× full-bore — 2× ½" and 2× ¾"
DHW Flow Restrictor
Caleffi — 5 L/min
Compatibility & Standards
Compatible With
EHS FLEX electric combi and system boilers, including ALC1-1PCO-14F (14kW Primus Flex Combi)
Chemical Treatment Standard
BS 7593 (treatment of water in heating systems)
Filling Loop Standard
WRAS Water Regulations Approval Scheme
Thermostat Compliance
Boiler Plus (Part L Building Regulations), OpenTherm
Warranty Impact
Extends EHS boiler warranty from 5 years to 7 years total when boiler is registered
Do I need this kit if I already have a magnetic filter and thermostat on site?
If existing components already meet the EHS specification (a compatible magnetic filter, WRAS filling loop, automatic bypass valve and Part L compliant thermostat), the individual missing items can be purchased separately. This kit is intended for a full, compliant installation in one order and is what qualifies the boiler for the 2-year extended warranty when purchased alongside it.
Why is the automatic bypass valve described as mandatory?
EHS's own installation manual states that without an automatic bypass valve, the boiler's paddle flow switch can detect inadequate flow as thermostatic radiator valves close down, triggering an F6 error code or a full boiler shutdown. EHS state this directly affects the manufacturer's warranty if omitted.
Does the Caleffi flow restrictor work with any EHS FLEX combi boiler?
The 5 L/min restrictor is the flow rate EHS specify to ensure a consistent temperature rise from combi models up to 14kW, such as the EHS Primus 14000C Flex (ALC1-1PCO-14F). For higher-output 3-phase combi models, EHS recommend checking the flow requirement against the boiler's own technical data sheet.
Is the thermostat wireless or does it need hard-wiring to the boiler?
The EPH Combi Pack 4 is a wireless RF thermostat and receiver. The receiver connects to the boiler's zero-volt thermostat terminal — this must never be supplied with live voltage, as doing so will damage the boiler's main circuit board and invalidate the warranty.
Does fitting this kit replace the need for a qualified installer?
No. EHS boilers must be installed by a qualified heating engineer and a Part P registered electrician, in accordance with the EHS installation manual, BS 7671, Building Regulations, and the Water Supply (Water Fittings) Regulations 1999. This kit supplies the compliant components; it does not replace the qualified installation itself.
