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What Are Isolation Valves?
Isolation valves are one of the most commonly used valve types in domestic plumbing. Their purpose is simple: they allow you to shut off water to a specific fixture or appliance without needing to turn off the entire supply. They're typically installed on individual taps, toilets, dishwashers, and washing machines.
The most common form is the quarter-turn, slotted-screw type valve. When the slot on the valve aligns with the pipe, it’s open; turn it 90 degrees and the flow stops. While inexpensive and easy to install, these valves can become stiff over time especially in hard water areas and may not always seal fully after years of use.
For improved performance, full bore isolation valves (which don’t restrict flow when open) are becoming a preferred choice, especially in heating systems or high-demand installations.
What Are Gate Valves?
Gate valves are typically used in older or larger plumbing systems – particularly on incoming mains or heating flow/return lines. As the name suggests, a gate valve uses a metal “gate” or wedge that is raised or lowered to start or stop flow. They’re controlled by a turning wheel or handle, and are designed to be either fully open or fully closed – not left halfway.
While they can handle high pressures and are generally reliable when installed correctly, gate valves are not ideal for frequent use. Over time, the internal mechanism can seize, and they are prone to leaking if not exercised regularly. For this reason, they are increasingly being replaced with ball valves in new installations.
What Are Ball Valves?
Ball valves are a highly reliable, modern option for flow control. They use a rotating ball with a hole through the centre. When the hole is aligned with the pipe, water flows freely. A 90-degree turn of the handle rotates the ball and stops the flow completely.
Ball valves are available in both standard bore and full bore types. Full bore valves allow maximum flow, making them a popular choice in heating systems where pressure drop needs to be minimised. They’re also favoured in commercial and industrial systems for their durability and ease of use.
Unlike gate valves, ball valves are excellent for quick shut-off and regular operation, which makes them ideal for situations where water flow needs to be controlled regularly or reliably in an emergency.
When to Use Each Valve Type
Isolation valves are ideal for individual appliances and fittings. They're useful for small-scale repairs or upgrades, as they let you isolate one item without draining the whole system.
Gate valves still have a place on older systems, and can be suitable for mains supply or heating lines where infrequent shut-off is needed but they should be replaced if they’re not functioning reliably.
Ball valves are the most versatile and dependable option for a wide range of uses from heating manifolds and pump valves to outdoor taps and service valves.
Understanding these differences helps you make smarter installation decisions, improves system reliability, and reduces the likelihood of callbacks or maintenance issues.
Need help choosing the right valve?
Whether you’re unsure what’s best for a heating system, renovation project or quick repair, our team at Collister and Glover is happy to help. We stock a full range of valves, including isolation, gate, and ball types and can advise on compatibility, flow rates, and installation tips. Visit us in branch or get in touch today!
