Drain Cocks
If you’re draining down a heating system, replacing a radiator, servicing a boiler or carrying out pipework alterations, you’re quite possibly in need of a drain cock, as they provide a controlled way to empty water from the system. Drain cocks are also known as MT plugs or draw-off taps and are typically installed at low points in a system, allowing water to be released safely.
At BES, we supply a comprehensive range of brass and DZR drain cocks, along with supporting components such as drain hoses, valve adaptors, inserts and washers. Our range covers the most common sizes used in domestic and light commercial plumbing, including 15mm, 22mm, 1/2" and 3/4", making it easy to find the right drain cock for the job. And, with fast shipping and free returns, shopping online for top-quality brass drain cocks couldn’t be easier.
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Drain Cock Types Explained
One of the most common questions we’re asked is “What’s the difference between Type A and Type B drain cocks?” The difference lies in how the valve seals.
Type A drain cocks feature a gland packing or stuffing box, which provides an additional seal around the spindle. This design helps prevent water leaking down the valve stem over time. They are chosen where the drain cock may be operated regularly, for long-term installations where durability is necessary or when a more robust seal is preferred.
Type B drain cocks use an O-ring seal rather than a gland packing. They have a simpler internal design and are typically used where the drain cock will be operated less frequently. Type B drain cocks are commonly found on straightforward domestic installations and where space or access is limited.
Type A and Type B drain cocks are not generally interchangeable, as the sealing methods and internal designs differ.
A Wide Range of Drain Cocks & Related Components
As trade specialists, BES stocks everything required for draining down and maintaining plumbing and heating systems, including:
Drain Cock, Type A
Our Type A drain cocks are available in brass and DZR, with options including standard compression, BSP, self-cutting and full-bore designs to suit a wide range of installations.
Drain Cock, Type B
Type B drain cocks offer a simpler sealing design and are commonly used on domestic systems where occasional draining is required. Available choices include Drain Cock Type B - 15mm Brass and Drain Cock Type B - 1/2" BSP Brass.
Drain Cocks (T-DOC Range)
Looking for a more modern, installer-friendly option? The T-DOC drain cock range includes Standard, Premium and Long Tail designs in 15mm sizes, offering a compact and reliable alternative to traditional drain cocks.
Sludge Cocks
Sludge cocks are used to drain water containing debris or sludge from heating systems. These are typically fitted at low points where sediment may collect. A popular choice here at BES is Sludge Cock - 15mm Compression DZR.
Drain Components
Our drain component range includes items such as the Water Drain Valve with Hose Tail – 1/2" BSP, ideal for controlled draining applications.
Drain Hoses
A drain hose allows water to be directed safely away from the system during draining. Our range includes durable hose options suitable for connection to standard drain cocks. Check out the popular Drain Hose - 15m x 1/2" bore Orange.
Valve Adaptors
Valve adaptors, such as self-cutting valve adaptors, are used with specific drain cocks or isolating valves where direct installation isn’t possible.
Drain Cock Inserts
Drain cock inserts provide a practical solution for maintaining or refurbishing compatible drain cock assemblies without full replacement. One of the most popular options is Retrofit Inserts for Nexgen Drain Cock - Pack of 10.
Washers
Replacement MT draw-off tap washers are available to help maintain a good seal and extend the service life of existing drain cocks - Arctic Hayes MT Draw Off Tap Washers - Pack of 5.
Installation & Use Considerations
Drain cocks should be installed in a position that allows a safe hose connection and water discharge, easy access for operation and controlled draining without damaging surrounding surfaces.
While drain cocks are simple components, installation and system draining should always be carried out with care. If you’re unsure about sizing, compatibility or correct placement, professional advice is recommended.
Drain Cocks And Fittings Delivered When You Need Them
With an extensive, well-stocked range and decades of industry knowledge, BES is a trusted source not just for drain cocks, but for all plumbing needs. Our focus on availability, service and fast delivery helps reduce downtime and keep installations running smoothly.
Need a second opinion before ordering? Contact our team, and we’ll help you find the right solution.
Drain Cocks FAQs
What’s the difference between Type A and Type B drain cocks?
Type A drain cocks use a gland packing for sealing, while Type B drain cocks use an O-ring. Type A is generally preferred for durability and frequent use.
Are Type A and Type B drain cocks interchangeable?
Not usually. The internal sealing methods differ, so replacement should match the original type where possible.
What’s the difference between brass and DZR drain cocks?
Standard brass drain cocks are widely used in domestic plumbing and perform well in normal water conditions. DZR (dezincification-resistant) brass drain cocks are designed to resist corrosion caused by aggressive water, helping to improve durability and reduce the risk of premature failure in certain areas.
When should I choose a DZR drain cock?
A DZR drain cock is typically recommended where water conditions are known to be more aggressive or where long-term reliability is a priority. They are often specified for commercial installations or in areas where standard brass components may be more prone to corrosion over time.
What is an MT plug?
An MT plug is another name for a drain cock or draw-off tap, used to drain water from a system.
How do I measure the size of a drain cock?
Drain cocks are measured by the pipe size they connect to, such as 15mm, 22mm, 1/2" or 3/4".
Do you stock washers for drain cocks?
Yes, replacement MT draw-off tap washers are available to help maintain a good seal.
What is a sludge cock used for?
A sludge cock is designed to drain water containing debris or sediment from heating systems, often fitted at low points.