Safety Valve
Safety valves for central heating systems, combi boilers, hot water cylinders, and electric water heaters: fixed-setting models at 3, 6, and 11 bar, 1/2 inch brass. Choose the correct opening pressure.
Products (7)
- Klepsan 5-Way Connection, 1'' – $13.20
- Pakkens 1/2'' Electric Water Heater Safety Valve, DN15, 11 Bar, Without Lever – $4.11
- Pakkens Adjustable Safety Relief Valve, DN15, Male, 1/2" – $13.89
- Pakkens DN15 Adjustable Steam Safety Valve, 1/2" – $24.98
- Pakkens Safety Valve, Male, 1/2", DN15, 6 Bar – $5.53
- Safety Relief Valve, Fixed Setting, 3 Bar, 1/2'' – $12.62
- Welko Safety Relief Valve, Female, Fixed Setting, 3 Bar, 1/2″, 110°C – $5.36
Brands: Klepsan · Pakkens · Welko
What does a safety valve do?
A safety valve is a safety device that opens automatically when pressure in a system or appliance exceeds a set value, relieving the excess pressure. When pressure rises to dangerous levels due to heated water expanding, a fault, or incorrect operation, it protects the boiler, hot water cylinder, electric water heater, and pipework from damage. The valve closes again once pressure returns to normal.
Which valve for which appliance?
- Central heating and combi boiler systems: Valves with a low opening pressure (e.g. 3 bar) are generally used.
- Hot water cylinders and hot water tanks: Valves rated to the maximum allowable pressure of the appliance are preferred.
- Electric water heaters: Valves with a discharge port, rated to the pressure specified by the manufacturer, are used.
- Fixed-setting models: Come with a factory-set opening pressure; the setting must not be tampered with.
The valve's opening pressure must not exceed the maximum allowable pressure of the weakest component in the system (boiler, hot water cylinder, tank, or pipe).
Installation rules
The safety valve should be installed as close as possible to the appliance being protected, and no isolating valve should be placed between the appliance and the safety valve. The discharge outlet must be left open or connected to a visible drain; plugging the discharge outlet renders the valve inoperative. The connection size (typically 1/2 inch) and whether the connection is male or female must suit the installation. For hot water applications, the valve's temperature rating should be verified.
Maintenance and inspection
Continuous dripping from the valve may indicate that system pressure is too close to the opening pressure, or that there is dirt in the valve seat. On valves equipped with a test lever, the valve's operation can be verified at regular intervals. Valves that have scaled up or that drip continuously should be replaced.
Frequently asked questions
Why is my combi boiler safety valve releasing water?
Excessive system pressure, low air charge in the expansion vessel, or a faulty valve can cause this.
Which opening pressure should I choose?
Select a value that does not exceed the maximum operating pressure shown on the label of the appliance being protected.
Is a safety valve the same as a pressure reducer?
No; a pressure reducer continuously limits the outlet pressure, whereas a safety valve only opens under excess pressure.
Where should the discharge outlet be connected?
It should be connected to a visible drain or funnel and must not be blocked.
Can the valve setting be changed?
The setting of fixed-setting valves must not be tampered with; if a different pressure is required, an appropriately rated valve should be selected.
Is it required alongside an expansion vessel?
Yes; the vessel absorbs expansion, while the valve is the last line of defense against unexpected excess pressure.