Expansion Tanks

Vertical Expansion Tanks

Vertical expansion vessels are cylindrical, membrane-type pressure vessels that stand on feet or, in small sizes, hang on the wall, absorbing the volume increase of heated water in closed heating and cooling circuits. Their upright layout means they occupy less floor area than a horizontal vessel of the same volume.

Small vertical vessels from 8 to 19 litres in PN10 are used on combi and small boiler circuits. Large footed shells are offered from 50 to 1000 litres in PN10, and in PN16 for selected volumes. The shell is made of steel with an electrostatic powder-coated exterior; an EPDM membrane separates the water side from the gas side. The vessels are manufactured in line with the Pressure Equipment Directive 2014/68/EU.

8–1000 Lvertical volume range

PN10 / PN16pressure classes

+110 °Cmax. vessel temperature

50%max. glycol content

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Main Applications

Central heating circuits in boiler rooms
Combi and wall-hung boiler circuits
Closed chiller and cooling water circuits
Solar heating systems (with a suitable membrane)
District heating substations

Technical Data

Shell type	Vertical cylindrical; footed or wall-mounted
Small volumes	8, 12, 19 L · PN10
Footed volumes	50, 100, 200, 300, 500, 750, 1000 L · PN10
PN16 volumes	100 and 200 L (from product names)
Max. temperature	+110 °C; +70 °C on potable and domestic water
Membrane continuous temperature	Up to +70 °C
Minimum operation	−10 °C, only with antifreeze-treated water
Fluid	Water or water with up to 50% glycol (fluid group 2)
Gas side	Dry air; nitrogen optional
Pre-charge	Stated on the label; set on site to suit the system
Connection size	By volume, depending on model
Directive	Pressure Equipment Directive 2014/68/EU

Material Options

Part	PN10 · 8–19 L	PN10 · 50–1000 L	PN16 · 100–200 L
Shell	Steel	Steel	Steel
Exterior	Electrostatic powder coating	Electrostatic powder coating	Electrostatic powder coating
Membrane	EPDM	EPDM (butyl optional)	EPDM (butyl optional)
Membrane replacement	Depending on model	Replaceable, depending on model	Replaceable, depending on model
Gas charge	Dry air	Dry air (nitrogen optional)	Dry air (nitrogen optional)
Mounting	Wall or floor	On feet on the floor	On feet on the floor

Siting note: Place the vessel in a frost-free indoor room where the label can be read and it is accessible from all sides; the connecting pipe must match the vessel inlet size. Pressure switches or safety valves are not connected directly to the membrane nut; a separate safety valve is added to the circuit.

Advantages

Small Footprint

The upright shell uses height.
Suits tight boiler rooms.

Wide Volume Choice

From 8 litres to 1000 litres.
From homes to industrial plants.

Two Pressure Classes

PN10 and PN16.
Handles static pressure in tall buildings.

Separate Gas Side

The membrane keeps water and gas apart.
No air entering the water, less corrosion.

Glycol Compatible

Water with up to 50% glycol.
Use on circuits with frost risk.

Construction and Design Features

Vertical cylindrical steel shell
EPDM membrane separating water and gas sides
Gas filling valve on top, water connection at the bottom
Floor-standing feet on large volumes
Label on the shell with volume, pressure and pre-charge

Send the circuit water volume, static height, safety valve opening pressure and operating temperatures through the Request a Quote form; we will calculate the vertical vessel volume and pressure class.

How to Choose?

Calculate water contentTotal the water in the boiler, pipework, radiators and heat exchangers.
Determine expansionCalculate the volume increase from the highest and lowest water temperatures.
Set pressure limitsDerive pre-charge from static pressure and final pressure from the safety valve setting.
Choose volume and classPick the vessel above the calculated nominal volume, with a PN class suited to final pressure.
Set the pre-chargeBefore commissioning, adjust the pre-charge to the static pressure of the installation.