Expansion Vessels

Potable

Potable water expansion vessels for use in domestic and commercial sealed chilled and hot water systems.

Advantages

Nitrogen gas filling for longer retention of pre-charge
With single-threaded steel connection and plastic insert (no flow-through function)

Technical Specifications

Maximum working pressure: 10 Bar (8 Bar for 750L)
Min/Max working temperature (bladder): -10/100°C (70°C for 1000L)
In accordance with Pressure Equipment Directive 2014/68/EU
Suitable for the addition of glycol-based antifreeze up to 50%
Coated aluminium (RAL 9006)
35 – 1000L as standard comes with feet

Heating

This is for use on domestic and commercial hot water systems, with each vessel being factory-tested before leaving the factory.

For sealed heating (acc. to EN12828) and cooling installations.

When the temperature in the installation rises, the system water will expand. The ‘expansion water’ is stored temporarily in the expansion vessel to keep the pressure in the installation at the correct level. Each vessel is factory-tested.

Advantages

The thread of the system connection is uncoated, ensuring a problem-free connection.
The fixed bag-type diaphragm prevents the water from contacting the vessel’s bare steel.
Nitrogen gas filling for longer maintenance of pre-pressure.

Technical Specifications

Maximum working pressure: 6 Bar
Vessels in accordance with EN13831
Min./max. temperature diaphragm: -10/70°C
In accordance with Pressure Equipment Directive 2014/68/EU
Suitable for systems with a maximum system temperature of 120°C
Diaphragm: EPDM
All welded construction & Zinc plated flange
Suitable for addition of glycol-based antifreeze up to 50% and ethanol-based antifreeze up to 30%
Red (RAL 3002) epoxy powder coating
35 – 1000L as standard come equipped with legs

Heating Sizing Assumptions

For guidance only!! For precise measurements/calculation, contact the CORE technical team.

Static Head options approximate (10m = 1 bar) for different storeys
Assumes vessel comes pre-charged just above static system pressure
Fluid behaviour with linear expansion coefficient for water (approx. 0.0003 per °C) starting from 10°C
Atmospheric pressure at 1 bar added to convert from gauge pressure to absolute pressure (standard industry practice)
Assumes water is the medium, and fluid properties don’t vary (no antifreeze/glycol consideration)

Expansion Vessel Sizing Calculator

Heating Expansion Vessel Calculator

System Volume (litres) Height of System (m) Max Working Temperature (°C) Final Working Pressure (bar) Safety Margin (%)

Potable Expansion Vessel Guidance

Assumptions Made:

2.8 bar vessel pre-charged
3 bar pressure reducing valve
Incoming cold water mains at 10°C
6 bar safety relief valve

Hot Water Cylinder Capacity (litres)	Vessel Size (litres)
Hot Water Cylinder Capacity (litres)	Max Temp 65°C	Max Temp 85°C
100	8	12
125	8	12
150	8	18
170	12	18
210	12	18
250	18	25
300	18	33
350	18	33
400	25	60
500	33	60
600	33	60
700	60	60
800	60	80
900	60	80
1000	60	100