Users Manual
1. General Information
Fixed membrane expansion vessels are designed in compliance with the basic safety requirements set by
the Directive of the European Parliament and Council 97/23/EC on the approximation of the laws of the
Member States relating to pressure equipment (further “PED”).
2. Description
Fixed membrane expansion vessels are, depending on the model, intended for operation in closed pressure
circuits or in closed DHW circuits. They enable absorbing an increased volume of heating medium caused by
heating. Expansion vessels shall not be used for other purposes than here described.
MB marked expansion vessels are designed for closed heating systems only. This type of expansion vessels
must not be used for technologies with DHW heating or technologies where fresh, oxygenated water
fl
ows
permanently in. HY marked expansion vessels are designed for hot water only.
3. Technical Information
Both the vessel types are made of high-quality steel, welded completely automatically in a certi
fi
ed procedure
according to valid technical standards. An impermeable and
fl
exible rubber membrane, very elastic and
resistant against high temperatures, is mounted into the vessel.
External protection is done with undercoat and
fi
nal paint, or by powder coating.
4. Installation
Before starting the installation, please make sure that the required volume of the expansion vessel has been
calculated by an authorized designer!
An expansion vessel for heating systems (
MB
line) shall be installed between a boiler and a mixing valve,
and preferably on the boiler return line. Between the boiler and expansion vessel no valve / closing device
shall be installed that could isolate the vessel completely. Only a safety valve shall be installed there,
calibrated precisely to the pressure in the boiler and circuit, that will eliminate any excess of the max.
pressure inside the vessel. It should also contain a pressure gauge. The vessel shall be installed in such a
manner that the
fi
lling/discharge valve can be accessed for air pressure adjustment anytime later.
An expansion vessel for heating DHW (
HY
line) shall be installed on the cold water inlet. Between the cold
water storage tank and expansion vessel no valve / closing device shall be installed that could isolate the
vessel completely. Only a safety valve shall be installed there, calibrated precisely to the pressure in the
boiler and circuit, that will eliminate any excess of the max. pressure inside the vessel. It should also contain
a pressure gauge.
During
fi
lling the system with water, air should be escaping through air vent valves. After air-bleeding make
sure that the pressure shown by the pressure gauge is slightly higher than the static pressure inside the
system. Keep the max. working pressure inside the system for the
fi
rst half a day, topping up water for the
escaped air. In order to prevent inner corrosion, the vessel shall be air-bled regularly.
Any installation with an expansion vessel shall include also a safety element that can limit pressure and
ensures that the upper pressure limit is never exceeded.
5. Maintenance
Maintenance shall be done by a specialized service centre only. At least once every 6 months it is necessary
to check through the
fi
lling valve that the air pressure keeps within the set range. Before checking air
pressure in an expansion vessel, heating water shall be discharged from the water side
fi
rst. The same
applies when dismantling an expansion vessel.
6. Safety Instructions
The following instructions shall be unconditionally adhered to:
- Filling pressure in the air bag in the expansion vessel shall never exceed the max. construction pressure
of the expansion vessel.
- It is forbidden to perforate the vessel, drill into it or weld any elements onto it.
- The working temperature and the working pressure of the vessel shall never be exceeded.
- Neither the manufacturer, nor the distributor will accept any responsibility for damage caused by
improper transport, or for damage to health or property, caused by wrong installation or improper use.
