Radiator Plug 1/2″

The radiator plug here is a 1/2″ blanking plug that seals an open tapping on a radiator. Most panel rads have four tappings, and once two take valves and one takes a bleed vent, the fourth needs closing off.

Fitting a radiator plug

New rads usually come with plugs and vents in the box, but they go missing, or an old rad needs a fresh one when it is refitted. This plug screws into the 1/2″ tapping and gives a watertight seal so the system holds its pressure.

• Size: 1/2″ thread
• Blanks off a spare radiator tapping
• Used on panel rads and many other types
• Goes in the bottom or top corner, whichever is free

Clean the old thread before fitting. A few turns of PTFE tape, or the washer if one is supplied, gives the seal. Tighten it firmly with the right key or spanner but stop before you crush the washer. Once the heating is back up to temperature, look at the joint again, because warm water finds a weak seal faster than cold.

If the tapping is the top corner opposite the bleed vent, think about whether a second vent would be more useful there. On long rads, two vents can make bleeding quicker.

Vents, keys and other bits are in our radiators and accessories area.

Specification

• Connection: 1/2″ thread for a radiator tapping
• Sizes: 1/2″
• Suitable for: Blanking off a spare radiator tapping

Common Questions

Why is my radiator plug leaking?

Usually the washer or tape has given up, or the plug was never fully tight. Drain the rad below the plug, remake the seal and tighten it, then check it again hot.

Do I need PTFE tape on a radiator plug?

If the plug has a sealing washer, the washer does the job and tape is not needed. A plug without one needs PTFE or a suitable thread sealant.

Can I swap a radiator plug for a bleed vent?

Yes, if the tapping is at the top of the rad and the thread matches. A second vent can help on long radiators where air gathers at both ends.

Radiator plugs from the Glasgow counter

Call in at Plumb Parts, 555 South Street, Glasgow G14 0QX. The counter opens Mon-Fri 8am-5pm and also Sat-Sun 8am-1pm. Online ordering is there as well.