The Trade-Tec Heating Expansion Vessel & Part L Filling Kit is a complete, ready-to-fit package for sealed central heating systems, manufactured by Zilmet and supplied under the Trade-Tec brand. Each kit bundles the pressure vessel itself with the safety valve, pressure gauge, wall mounting bracket and braided filling hose needed to complete a Part L compliant installation in a single order, saving installers from sourcing ancillaries separately.
Every vessel is factory pressure-tested before despatch and finished in a durable powder-coated red shell, designed to accommodate the thermal expansion of water in a closed heating circuit and protect the boiler, pipework and valves from over-pressurisation. The range is available in four capacities — 8, 12, 18 and 25 litres — to suit system sizes from a small flat to a larger domestic installation, with a consistent G3/4″ connection across every size.
4 bar
Max Working Pressure
Please Note
This kit is designed for sealed heating systems only and is not WRAS-approved for potable (drinking) water use. Trade-Tec also produce a separate potable expansion vessel range for unvented hot water cylinders — check the connection type and application on the vessel label before installation.
Important Safety Information
The system in which this vessel is installed must include a pressure-limiting device such as a pressure relief valve, and installation should only be carried out by a suitably qualified, Gas Safe or equivalent registered installer. Sizing calculations must be performed by a competent engineer — using an incorrectly sized vessel can result in reduced service life, property damage or personal injury.
Good to Know
In hard water areas, fitting a water softener such as an ActivFlo unit is recommended to reduce the risk of calcium deposits forming in the vessel and system over time.
Complete Part L Kit
Includes vessel, combined safety valve with pressure gauge, and a braided flexible filling loop with isolating valves — everything needed for one compliant, professional install.
Factory Pressure-Tested
Every vessel is 100% factory tested before it leaves production, checking the weld seams and internal membrane are leak-free from day one on site.
Replaceable Membrane
The internal diaphragm can be replaced in the field without swapping the whole vessel, keeping long-term maintenance costs down and extending the working life of the unit.
Durable Powder-Coated Finish
The rouge red powder-coated shell resists corrosion in damp plant rooms and airing cupboards, and gives a neat, professional appearance in visible installations.
Wall Mounting Bracket Included
A dedicated mounting bracket is supplied with every kit, giving a secure, properly supported fixing point rather than relying on pipework alone to carry the vessel's weight.
Wide Sizing Range
Available across 8, 12, 18 and 25 litre capacities on the same G3/4″ connection, covering everything from compact systems to larger domestic heating installations.
Vessel Specification
Manufacturer
Zilmet (Trade-Tec range)
Application
Sealed central heating systems (not potable water)
Max. working pressure
4 bar
Factory pre-charge pressure
1 bar (±20% tolerance)
Max. system temperature
90°C (with suitable thermostatic control)
Vessel temperature range
-10°C to 70°C
External finish
Powder-coated, rouge red
Membrane
Flexible synthetic diaphragm, field-replaceable
Compliance
Manufactured to 2014/68/EU Pressure Equipment Directive
Kit Contents
Included
Expansion vessel, combined safety relief valve with pressure gauge, braided flexible filling loop with isolating valves, wall mounting bracket
Standard
Designed to support Part L compliant installation
Capacity
Product Code
Diameter
Height
Connection
8 Litre
130G000802
217mm
338mm
G3/4″
12 Litre
130G001202
267mm
334mm
G3/4″
18 Litre
130G001802B
317mm
299mm
G3/4″
24 Litre
130G002502B*
317mm
341mm
G3/4″
Is this kit suitable for a potable hot water cylinder?
No. This is a heating-only expansion vessel and is not WRAS-approved for potable water. For an unvented hot water cylinder, a dedicated potable expansion vessel is required instead.
What size vessel do I need for my system?
Vessel sizing depends on total system water content, boiler output, and the working pressures of the system and safety relief valve. This calculation should always be carried out by a qualified heating engineer using the correct sizing formula — do not select a size by system type alone.
What is included in the Part L Filling Kit?
Each kit includes the expansion vessel itself, a combined safety relief valve with integral pressure gauge, a braided flexible filling loop with isolating valves, and a wall mounting bracket.
Can the pre-charge pressure be adjusted?
Yes, but only by a suitably qualified technician. Any change to the factory-set pre-charge must ensure the maximum working pressure of the system is never exceeded, and the new value should be recorded on the vessel's label.
How is the vessel maintained after installation?
The pre-charge pressure should be checked at least once a year against the value on the vessel label, and the outer casing can be cleaned periodically using water and mild soap only.
