REF XVES050055 ARB18ME11611723

Reliance - Aquasystem ARB18 Litre Potable Expansion Vessel C/W Bracket XVES050055

In stock
In stock
Secure Payment
  • Free delivery (postcode specific) *
  • Delivery within 24 to 48 hours
Delivery method
  • At home between 01/10/2021 and 04/10/2021 for any order placed before 5 pm (Free shipping)
  • At home between 29/09/2021 and 30/09/2021
Product details
  • Use
    Domestic supply water
  • Threading
    3/4" (20x27)
  • Shape of the tank
  • warranty
    2 years

Aquasystem 18 Litre Potable Expansion Vessel C/W Bracket XVES050055



H x 430mm - D x 280mm


3/4 inch

All Aquasystem expansion vessels are supplied with a replaceable membrane, which separates the water and air, to prevent contamination of the water system, corrosion of the expansion vessel or pressure loss in the water system.

The main purpose of an expansion vessel is to compensate for the increase in volume of water due to the varying water temperatures in hot water or heating systems. When water is heated it expands and as water is not compressible this increased volume will create a rise in pressure within the system. As an example, water being heated from 0°C-100°C will increase by approx 4.5%.

The expansion vessel allows for this extra space, as when water temperature increases the membrane inside the vessel inflates to allow the water to fill the vessel. The membrane will continue to expand until the system reaches its maximum temperature. Once this has been reached the membrane will be fully inflated and takes up the capacity of the vessel shell. Gradually the temperature will drop, which will in turn decrease the volume of water. Due to the pressure from the pressurised air surrounding the membrane, water will start to exit the vessel until the membrane is deflated.


Stainless steel bolted flange prevents corrosion.

Extra wide membrane opening prevents noise caused by restricted flow.

Internal membrane preventing water contact with the steel shell, stopping internal corrosion.

Vessel can be serviced without being removed due to replaceable membrane.

Vessel has pre-charged valve for topping up air pressure.

Welded fixing bracket on tank & wall mounting fittings included for ease of installation.

Vessel Size Guide:

Vessel Capacity:Vessel Dimensions:
2 LitreHeight: 265mm Diameter: 110mm
8 LitreHeight: 310mm Diameter: 200mm
12 LitreHeight: 295mm Diameter: 280mm
18 LitreHeight: 465mm Diameter: 280mm
24 LitreHeight: 492mm Diameter: 280mm
35 LitreHeight: 440mm Diameter: 365mm

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*Free shipping availability will depend on your postcode, this information will be available at checkout.