Bottom Inlet Valve 3/8″

A bottom inlet valve with a 3/8″ thread is the one to look for when the cistern you are working on takes the smaller connection. Some cisterns take 3/8″ rather than the more usual 1/2″, and a valve with the wrong thread simply will not fit.

Checking you need this bottom inlet valve

Look at the old valve’s tail or check the cistern hole and supply connector. If the flexible hose has a 3/8″ nut, this is the size you need. Getting it right first time saves a second trip to the counter.

• 3/8″ thread on the inlet
• Body height can be adjusted
• Float sets the water level
• Compact and refills quietly

Isolate the supply, flush and empty the cistern, then remove the old valve. Fit the new one with its washer, set the height and tighten the backnut by hand and a little more. Connect the supply, open it slowly and set the float so the water stops a little below the overflow.

Flush a few times and make sure it shuts off fully. A valve that never quite closes will keep trickling into the pan and wasting water.

Matching flush valves and washers are in our cistern fittings section.

Finding 3/8″ valves in Glasgow

If you are unsure of the thread, bring the old valve to Plumb Parts, 555 South Street, Glasgow G14 0QX, or order online. The counter hours are Mon-Fri 8am-5pm and Sat-Sun 8am-1pm.

Specification

• Connection: 3/8″ bottom inlet
• Sizes: 3/8″
• Suitable for: toilet cisterns that take a 3/8″ inlet fed from below

Common Questions

How can I tell a 3/8″ inlet from a 1/2″ one?

Check the nut on the flexible hose or connector under the cistern. A 3/8″ nut is clearly smaller than the more common 1/2″, and if you bring the old valve in it can be compared on the counter.

Can a 1/2″ supply connector go on this valve?

No, the connector has to match the 3/8″ tail. Use a 3/8″ connector or flexible hose so the thread pulls up properly and seals.

The cistern fills slowly after fitting. What is wrong?

First check the isolating valve below the cistern is fully open. Then look for grit or debris in the inlet. Low mains pressure on an upper floor can also slow the fill.