✨ New Arrivals Just Dropped!Explore
Trade-Tec Potable Expansion Vessel - 8L to 35L
HomeStore

Trade-Tec Potable Expansion Vessel - 8L to 35L

Trade-Tec Potable Expansion Vessel - 8L to 35L

The Trade-Tec Potable Expansion Vessel — manufactured by Intatec — is a WRAS-approved pressure vessel designed specifically for domestic and light-commercial potable (drinking water) hot water systems, including unvented cylinders and pressurised water heaters. Available in 8 L, 12 L, 19 L, 24 L and 35 L capacities, it accommodates the thermal expansion of water in a sealed system, protecting pipework, valves and the cylinder itself from over-pressurisation. Every vessel is 100% factory tested and supplied with a mounting bracket — ready for a straightforward installation.

8 bar
Max working pressure
99 °C
Max working temperature
70 °C
Max membrane temperature
2.5 bar
Pre-charge (8–24 L)
5 sizes
8 L to 35 L
Potable water rated: This vessel uses a food-safe membrane approved for contact with drinking water. It is not interchangeable with heating system expansion vessels, which use different membrane materials not suitable for potable circuits.
Sizing note: Always size the expansion vessel using your cylinder manufacturer's guidance or a recognised hydraulic calculation (e.g. CIPHE / CIBSE method), based on the total cylinder volume, incoming water pressure and the T&P relief valve set pressure. An undersized vessel will cause nuisance discharge from the T&P valve; an oversized vessel is harmless but wastes space.
Key Features
100% Factory Tested

Every Trade-Tec vessel is pressure-tested at the factory before despatch. This ensures the vessel, weld seams and membrane are all leak-free and perform to specification from the moment they arrive on site — a significant advantage over untested vessels that can fail during commissioning.

Interchangeable Membrane

The membrane can be replaced in the field without replacing the whole vessel. This extends service life considerably — when a membrane reaches end-of-life after many years, only the membrane needs sourcing, keeping maintenance costs low and reducing material waste.

Powder-Coated Exterior

The outer shell carries a durable powder-coated finish that resists corrosion in damp plant rooms and airing cupboards. The clean appearance suits installations where the vessel is visible, and the finish holds up to the condensation and humidity typical in hot water plantrooms.

Galvanised Steel Flange

The vessel connection flange is galvanised steel, providing a corrosion-resistant, robust connection point. The standard connection simplifies integration with the inlet control group of an unvented cylinder or the pipework of any pressurised DHW system.

Welded Centre Seam

The vessel body is constructed with a welded centre seam — a manufacturing method that produces a strong, reliable joint across the full vessel service life and eliminates the risk of joint-related leaks common in older bolted-flange designs.

Supplied with Mounting Bracket

A wall-mounting bracket is included in the box, so no separate bracket needs sourcing. The vessel can be wall-hung to keep the floor clear and maintain tidy pipework routing — particularly useful in the confined space of an airing cupboard or cylinder cupboard.

Technical Specifications
Parameter Details
Available capacities 8 L, 12 L, 19 L, 24 L, 35 L
Max working pressure 8 bar
Max working temperature 99 °C
Max membrane temperature 70 °C
Pre-charge pressure (8–24 L) 2.5 bar
Pre-charge pressure (35 L) 1.5 bar
Application Potable (drinking) water — DHW unvented systems
Exterior finish Powder-coated steel
Flange material Galvanised steel
Seam type Welded centre seam
Membrane Interchangeable, potable water approved
Factory testing 100% pressure tested prior to despatch
Bracket included Yes — mounting bracket supplied
Manufacturer Intatec (Trade-Tec range), Hixon, Stafford, UK
Warranty 2 years manufacturing warranty
Datasheet ref. Intatec Technical Datasheet E&OE 02/2024
Model Reference Codes
Part Number Description
TRPVES08 Trade-Tec 8 Litre Potable Expansion Vessel
TRPVES12 Trade-Tec 12 Litre Potable Expansion Vessel
TRPVES18 Trade-Tec 19 Litre Potable Expansion Vessel
TRPVES24 Trade-Tec 24 Litre Potable Expansion Vessel
TRPVES35 Trade-Tec 35 Litre Potable Expansion Vessel
Frequently Asked Questions
Why does an unvented hot water system need an expansion vessel?
When water is heated it expands. In a sealed (unvented) system there is nowhere for this extra volume to go without an expansion vessel. The vessel's flexible membrane absorbs the expanded volume, keeping system pressure within safe operating limits and preventing the T&P relief valve from discharging. Without a correctly sized expansion vessel, nuisance T&P discharges occur, and repeated pressure spikes shorten the life of valves and pipework.
Can this vessel be used on a central heating circuit?
No. The Trade-Tec Potable Expansion Vessel is designed and approved exclusively for potable (drinking) water circuits such as unvented hot water cylinders and pressurised water heaters. Central heating circuits require a heating-rated expansion vessel with a different membrane material (not food-safe). Using a heating vessel on a potable circuit is a Water Regulations violation; using a potable vessel on a heating circuit may cause premature membrane failure.
What size expansion vessel do I need for my cylinder?
The correct vessel size depends on the cylinder volume, the incoming cold water pressure, the pre-charge pressure of the vessel and the T&P relief valve set pressure. Most cylinder manufacturers publish a sizing table in their installation manual — always refer to this first. As a very rough guide, an 8 L vessel suits cylinders up to about 120 L on typical UK mains pressure (3–4 bar); larger cylinders or higher supply pressures require proportionally larger vessels.
How often should the expansion vessel pre-charge pressure be checked?
The pre-charge pressure should be checked at every annual service of the unvented system — it is one of the standard checks required under Building Regulations maintenance guidance. The vessel must be isolated and the water side depressurised before checking with a tyre-type gauge. The pre-charge for 8–24 L Trade-Tec vessels is 2.5 bar; for the 35 L model it is 1.5 bar. Top up with dry nitrogen or clean, dry air if the charge has dropped.
Where should the expansion vessel be positioned in the system?
The vessel should be connected to the cold water inlet pipework, downstream of the pressure-reducing valve but upstream of the non-return valve — or in the dedicated port on the inlet control group if one is provided. Mount it vertically with the connection at the bottom unless the manufacturer specifies otherwise. The supplied mounting bracket allows wall-hanging to keep the vessel clear of the floor and in a stable orientation.
Select Size
From $17.48

Original: $49.94

-65%
Trade-Tec Potable Expansion Vessel - 8L to 35L—

$49.94

$17.48

Trade-Tec Potable Expansion Vessel - 8L to 35L

The Trade-Tec Potable Expansion Vessel — manufactured by Intatec — is a WRAS-approved pressure vessel designed specifically for domestic and light-commercial potable (drinking water) hot water systems, including unvented cylinders and pressurised water heaters. Available in 8 L, 12 L, 19 L, 24 L and 35 L capacities, it accommodates the thermal expansion of water in a sealed system, protecting pipework, valves and the cylinder itself from over-pressurisation. Every vessel is 100% factory tested and supplied with a mounting bracket — ready for a straightforward installation.

8 bar
Max working pressure
99 °C
Max working temperature
70 °C
Max membrane temperature
2.5 bar
Pre-charge (8–24 L)
5 sizes
8 L to 35 L
Potable water rated: This vessel uses a food-safe membrane approved for contact with drinking water. It is not interchangeable with heating system expansion vessels, which use different membrane materials not suitable for potable circuits.
Sizing note: Always size the expansion vessel using your cylinder manufacturer's guidance or a recognised hydraulic calculation (e.g. CIPHE / CIBSE method), based on the total cylinder volume, incoming water pressure and the T&P relief valve set pressure. An undersized vessel will cause nuisance discharge from the T&P valve; an oversized vessel is harmless but wastes space.
Key Features
100% Factory Tested

Every Trade-Tec vessel is pressure-tested at the factory before despatch. This ensures the vessel, weld seams and membrane are all leak-free and perform to specification from the moment they arrive on site — a significant advantage over untested vessels that can fail during commissioning.

Interchangeable Membrane

The membrane can be replaced in the field without replacing the whole vessel. This extends service life considerably — when a membrane reaches end-of-life after many years, only the membrane needs sourcing, keeping maintenance costs low and reducing material waste.

Powder-Coated Exterior

The outer shell carries a durable powder-coated finish that resists corrosion in damp plant rooms and airing cupboards. The clean appearance suits installations where the vessel is visible, and the finish holds up to the condensation and humidity typical in hot water plantrooms.

Galvanised Steel Flange

The vessel connection flange is galvanised steel, providing a corrosion-resistant, robust connection point. The standard connection simplifies integration with the inlet control group of an unvented cylinder or the pipework of any pressurised DHW system.

Welded Centre Seam

The vessel body is constructed with a welded centre seam — a manufacturing method that produces a strong, reliable joint across the full vessel service life and eliminates the risk of joint-related leaks common in older bolted-flange designs.

Supplied with Mounting Bracket

A wall-mounting bracket is included in the box, so no separate bracket needs sourcing. The vessel can be wall-hung to keep the floor clear and maintain tidy pipework routing — particularly useful in the confined space of an airing cupboard or cylinder cupboard.

Technical Specifications
Parameter Details
Available capacities 8 L, 12 L, 19 L, 24 L, 35 L
Max working pressure 8 bar
Max working temperature 99 °C
Max membrane temperature 70 °C
Pre-charge pressure (8–24 L) 2.5 bar
Pre-charge pressure (35 L) 1.5 bar
Application Potable (drinking) water — DHW unvented systems
Exterior finish Powder-coated steel
Flange material Galvanised steel
Seam type Welded centre seam
Membrane Interchangeable, potable water approved
Factory testing 100% pressure tested prior to despatch
Bracket included Yes — mounting bracket supplied
Manufacturer Intatec (Trade-Tec range), Hixon, Stafford, UK
Warranty 2 years manufacturing warranty
Datasheet ref. Intatec Technical Datasheet E&OE 02/2024
Model Reference Codes
Part Number Description
TRPVES08 Trade-Tec 8 Litre Potable Expansion Vessel
TRPVES12 Trade-Tec 12 Litre Potable Expansion Vessel
TRPVES18 Trade-Tec 19 Litre Potable Expansion Vessel
TRPVES24 Trade-Tec 24 Litre Potable Expansion Vessel
TRPVES35 Trade-Tec 35 Litre Potable Expansion Vessel
Frequently Asked Questions
Why does an unvented hot water system need an expansion vessel?
When water is heated it expands. In a sealed (unvented) system there is nowhere for this extra volume to go without an expansion vessel. The vessel's flexible membrane absorbs the expanded volume, keeping system pressure within safe operating limits and preventing the T&P relief valve from discharging. Without a correctly sized expansion vessel, nuisance T&P discharges occur, and repeated pressure spikes shorten the life of valves and pipework.
Can this vessel be used on a central heating circuit?
No. The Trade-Tec Potable Expansion Vessel is designed and approved exclusively for potable (drinking) water circuits such as unvented hot water cylinders and pressurised water heaters. Central heating circuits require a heating-rated expansion vessel with a different membrane material (not food-safe). Using a heating vessel on a potable circuit is a Water Regulations violation; using a potable vessel on a heating circuit may cause premature membrane failure.
What size expansion vessel do I need for my cylinder?
The correct vessel size depends on the cylinder volume, the incoming cold water pressure, the pre-charge pressure of the vessel and the T&P relief valve set pressure. Most cylinder manufacturers publish a sizing table in their installation manual — always refer to this first. As a very rough guide, an 8 L vessel suits cylinders up to about 120 L on typical UK mains pressure (3–4 bar); larger cylinders or higher supply pressures require proportionally larger vessels.
How often should the expansion vessel pre-charge pressure be checked?
The pre-charge pressure should be checked at every annual service of the unvented system — it is one of the standard checks required under Building Regulations maintenance guidance. The vessel must be isolated and the water side depressurised before checking with a tyre-type gauge. The pre-charge for 8–24 L Trade-Tec vessels is 2.5 bar; for the 35 L model it is 1.5 bar. Top up with dry nitrogen or clean, dry air if the charge has dropped.
Where should the expansion vessel be positioned in the system?
The vessel should be connected to the cold water inlet pipework, downstream of the pressure-reducing valve but upstream of the non-return valve — or in the dedicated port on the inlet control group if one is provided. Mount it vertically with the connection at the bottom unless the manufacturer specifies otherwise. The supplied mounting bracket allows wall-hanging to keep the vessel clear of the floor and in a stable orientation.

Product Information

Shipping & Returns

Description

The Trade-Tec Potable Expansion Vessel — manufactured by Intatec — is a WRAS-approved pressure vessel designed specifically for domestic and light-commercial potable (drinking water) hot water systems, including unvented cylinders and pressurised water heaters. Available in 8 L, 12 L, 19 L, 24 L and 35 L capacities, it accommodates the thermal expansion of water in a sealed system, protecting pipework, valves and the cylinder itself from over-pressurisation. Every vessel is 100% factory tested and supplied with a mounting bracket — ready for a straightforward installation.

8 bar
Max working pressure
99 °C
Max working temperature
70 °C
Max membrane temperature
2.5 bar
Pre-charge (8–24 L)
5 sizes
8 L to 35 L
Potable water rated: This vessel uses a food-safe membrane approved for contact with drinking water. It is not interchangeable with heating system expansion vessels, which use different membrane materials not suitable for potable circuits.
Sizing note: Always size the expansion vessel using your cylinder manufacturer's guidance or a recognised hydraulic calculation (e.g. CIPHE / CIBSE method), based on the total cylinder volume, incoming water pressure and the T&P relief valve set pressure. An undersized vessel will cause nuisance discharge from the T&P valve; an oversized vessel is harmless but wastes space.
Key Features
100% Factory Tested

Every Trade-Tec vessel is pressure-tested at the factory before despatch. This ensures the vessel, weld seams and membrane are all leak-free and perform to specification from the moment they arrive on site — a significant advantage over untested vessels that can fail during commissioning.

Interchangeable Membrane

The membrane can be replaced in the field without replacing the whole vessel. This extends service life considerably — when a membrane reaches end-of-life after many years, only the membrane needs sourcing, keeping maintenance costs low and reducing material waste.

Powder-Coated Exterior

The outer shell carries a durable powder-coated finish that resists corrosion in damp plant rooms and airing cupboards. The clean appearance suits installations where the vessel is visible, and the finish holds up to the condensation and humidity typical in hot water plantrooms.

Galvanised Steel Flange

The vessel connection flange is galvanised steel, providing a corrosion-resistant, robust connection point. The standard connection simplifies integration with the inlet control group of an unvented cylinder or the pipework of any pressurised DHW system.

Welded Centre Seam

The vessel body is constructed with a welded centre seam — a manufacturing method that produces a strong, reliable joint across the full vessel service life and eliminates the risk of joint-related leaks common in older bolted-flange designs.

Supplied with Mounting Bracket

A wall-mounting bracket is included in the box, so no separate bracket needs sourcing. The vessel can be wall-hung to keep the floor clear and maintain tidy pipework routing — particularly useful in the confined space of an airing cupboard or cylinder cupboard.

Technical Specifications
Parameter Details
Available capacities 8 L, 12 L, 19 L, 24 L, 35 L
Max working pressure 8 bar
Max working temperature 99 °C
Max membrane temperature 70 °C
Pre-charge pressure (8–24 L) 2.5 bar
Pre-charge pressure (35 L) 1.5 bar
Application Potable (drinking) water — DHW unvented systems
Exterior finish Powder-coated steel
Flange material Galvanised steel
Seam type Welded centre seam
Membrane Interchangeable, potable water approved
Factory testing 100% pressure tested prior to despatch
Bracket included Yes — mounting bracket supplied
Manufacturer Intatec (Trade-Tec range), Hixon, Stafford, UK
Warranty 2 years manufacturing warranty
Datasheet ref. Intatec Technical Datasheet E&OE 02/2024
Model Reference Codes
Part Number Description
TRPVES08 Trade-Tec 8 Litre Potable Expansion Vessel
TRPVES12 Trade-Tec 12 Litre Potable Expansion Vessel
TRPVES18 Trade-Tec 19 Litre Potable Expansion Vessel
TRPVES24 Trade-Tec 24 Litre Potable Expansion Vessel
TRPVES35 Trade-Tec 35 Litre Potable Expansion Vessel
Frequently Asked Questions
Why does an unvented hot water system need an expansion vessel?
When water is heated it expands. In a sealed (unvented) system there is nowhere for this extra volume to go without an expansion vessel. The vessel's flexible membrane absorbs the expanded volume, keeping system pressure within safe operating limits and preventing the T&P relief valve from discharging. Without a correctly sized expansion vessel, nuisance T&P discharges occur, and repeated pressure spikes shorten the life of valves and pipework.
Can this vessel be used on a central heating circuit?
No. The Trade-Tec Potable Expansion Vessel is designed and approved exclusively for potable (drinking) water circuits such as unvented hot water cylinders and pressurised water heaters. Central heating circuits require a heating-rated expansion vessel with a different membrane material (not food-safe). Using a heating vessel on a potable circuit is a Water Regulations violation; using a potable vessel on a heating circuit may cause premature membrane failure.
What size expansion vessel do I need for my cylinder?
The correct vessel size depends on the cylinder volume, the incoming cold water pressure, the pre-charge pressure of the vessel and the T&P relief valve set pressure. Most cylinder manufacturers publish a sizing table in their installation manual — always refer to this first. As a very rough guide, an 8 L vessel suits cylinders up to about 120 L on typical UK mains pressure (3–4 bar); larger cylinders or higher supply pressures require proportionally larger vessels.
How often should the expansion vessel pre-charge pressure be checked?
The pre-charge pressure should be checked at every annual service of the unvented system — it is one of the standard checks required under Building Regulations maintenance guidance. The vessel must be isolated and the water side depressurised before checking with a tyre-type gauge. The pre-charge for 8–24 L Trade-Tec vessels is 2.5 bar; for the 35 L model it is 1.5 bar. Top up with dry nitrogen or clean, dry air if the charge has dropped.
Where should the expansion vessel be positioned in the system?
The vessel should be connected to the cold water inlet pipework, downstream of the pressure-reducing valve but upstream of the non-return valve — or in the dedicated port on the inlet control group if one is provided. Mount it vertically with the connection at the bottom unless the manufacturer specifies otherwise. The supplied mounting bracket allows wall-hanging to keep the vessel clear of the floor and in a stable orientation.