Expansion vessels for heating systems in Hagen – 3 and 6 bar
Expansion vessel for heating with 35 or 50 litres and 3 or 6 bar operating pressure, plus cap valves and a safety group for water heaters. These are order items: we order them into our Hagen warehouse for you, and the collection date comes with our reply to your enquiry.
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- Enquiry instead of checkout
- Shipping on enquiry
- 6versions in this category
- Heating expansion vessel – white, 35 or 5...Example product · from €133,78 incl. VAT, plus shipping · view product
- Hagen warehouseCollection by appointment, shipping on enquiry
Expansion Vessels at a glance: choose an option and add it to your enquiry list
Heating expansion vessel – white, 35 or 50 litres
2 Ausführungen: 35 litres · 50 litres
Optiline WSE safety group – for water heaters, 12 or 18 litres
2 Ausführungen: WSE 12 · WSE 18
Brass expansion vessel isolation valve – drain, 3/4″ or 1″
2 Ausführungen: 3/4″ · 1″- Featured
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Why does a heating system need an expansion vessel?
Heating water expands as it warms up. In a sealed system, this would increase the pressure until the safety valve opened. The expansion vessel takes in the additional water against a gas cushion and releases it again as it cools. This keeps system pressure fluctuations small and the safety valve closed.
| Item | Application | Versions | Features |
|---|---|---|---|
| Heating expansion vessel | sealed heating, solar and cooling circuits | 35 or 50 litres, maximum operating pressure 3 or 6 bar | steel, white epoxy powder coating RAL 9010, galvanised clamping rings, welded feet |
| Optiline WSE safety group | sealed drinking water heaters to DIN EN 1488 | WSE 12 or WSE 18 with a 12 or 18 litre diaphragm expansion vessel, connection G 3/4 | 6, 8 or 10 bar safety valve, non-return valve with test facility, 3-way ball valve, discharge funnel |
| Lockshield service valve | isolating and draining the vessel during maintenance | 3/4 or 1 inch | brass, drain valve, sealing wire |
Find the boiler safety group with safety valve under Heating valves, circulation pumps under Pumps and the full range under Heating technology.
Expansion vessel pre-charge: what does the value mean?
The pre-charge is the gas pressure in the vessel, measured without water pressure. It must suit the system. If it is too low, the vessel takes in a lot of water during filling, leaving too little space when the water heats up. If it is too high, there is too little water reserve when cold, and the pressure drops as the system cools.
The correct pre-charge depends mainly on the height of the system above the vessel. The system filling pressure is slightly higher; the heating installer sets both. Measurement is taken at the vessel's gas valve with the water side isolated and depressurised. This is precisely why the lockshield service valve with drain is fitted before the vessel.
35 or 50 litres: what determines the size?
The required volume depends on the water content of the entire system, including the heat generator, pipes and heat emitters, the maximum flow temperature and the pressure range between the pre-charge and the safety valve opening pressure. The old vessel provides an initial guide: its nominal volume and operating pressure are shown on the rating plate. If the system has been extended, for example with radiators or underfloor heating, this volume may be too small.
For operating pressure, the vessel must be rated at least for the safety valve opening pressure. If the system is protected at 3 bar, as with our boiler safety group, the 3 bar version is sufficient. The 6 bar version is intended for higher-pressure systems.
Drinking water: a dedicated safety group rather than a heating vessel
Heating vessels must not be used in drinking water installations. For sealed drinking water heaters, we offer the Optiline WSE safety group to DIN EN 1488. It combines a safety valve, a non-return valve with test facility, a ball valve and a diaphragm expansion vessel to DIN 4807-5, and has an integrated suspension bracket.
Installation and maintenance
- Lockshield service valve: fitted in the pipe to the vessel. The cap and sealing wire prevent accidental closure; the drain depressurises the vessel for testing.
- Positioning: the 35 and 50 litre heating vessels have welded feet.
- Installer: the heating installer carries out installation and also sets the pre-charge and filling pressure. Work on the drinking water installation, such as the safety group, is for a registered installer; electrical work on the system is for a qualified electrician.
Collection in Hagen or delivery
Expansion vessels, the safety group and the lockshield service valve are order items. Once they arrive, collect them from our Hagen warehouse; our reply will tell you when.
- Select the item and, for the vessel, the volume and operating pressure.
- Add it to the enquiry list, with a suitable lockshield service valve if desired.
- Send your enquiry, ideally with a photo of the old vessel's rating plate.
- We will contact you by email or telephone with the price and the date from which the goods are ready.
Warehouse: Im Mühlenwert 22, 58135 Hagen. Shop: Eilper Straße 29, 58091 Hagen. Shipping on request. More information: Collection and enquiries and Locations.
Frequently asked questions about expansion vessels
Faults, drinking water, lockable service valves and cylinder size: what matters before your enquiry.
How can I tell if the expansion vessel is no longer working properly?
A large fluctuation in system pressure is a typical sign. During heating, pressure rises to the opening pressure and the safety valve drips; when cold, it falls so far that you often need to top up the water. An installer should then check the pre-charge pressure and replace the vessel if necessary.
Can a heating expansion vessel be used for drinking water?
No. Drinking water requires vessels specifically approved for that purpose. For unvented water heaters, we offer the Optiline WSE safety group with a 12 or 18 litre diaphragm expansion vessel and a safety valve rated at 6, 8 or 10 bar.
What is the lockable service valve for?
It lets you isolate the vessel for maintenance and release pressure on the water side through the integrated drain. It stays open during operation, secured by a cap and sealing wire. We offer brass versions in 3/4 and 1 inch.
What cylinder size does the Optiline WSE suit?
According to the product information, it suits water heaters up to 300 litres (WSE 12) or 460 litres (WSE 18). Both have a G 3/4 connection.
How often should the expansion vessel be checked?
At every heating service and whenever system pressure fluctuates noticeably. Both pre-charge and filling pressure are checked; both must suit the height of the system.
Can I take an expansion vessel away immediately?
Expansion vessels are order items. Our reply to your enquiry will confirm when your vessel will be ready for collection from our Hagen warehouse.