Tap connector sizes are written pipe size by tap thread: JG Speedfit and Conex Bänninger both name theirs this way. A 15mm x 1/2" connector joins 15 mm pipe to a tap with a 1/2" BSP thread, and a 22mm x 3/4" joins 22 mm pipe to a 3/4" BSP thread. JG Speedfit makes its push-fit tap connectors in 10mm x 1/2", 15mm x 1/2", 15mm x 3/4" and 22mm x 3/4".
Reading the size
The first number is the pipe the connector takes, in millimetres. The second is the thread on the tap, in BSP inches. On the tap connectors below, the nut has the female thread and screws onto a male thread on the tap.
| Size | Pipe | Tap thread | Made by |
|---|---|---|---|
| 10mm x 1/2" | 10 mm | 1/2" BSP | JG Speedfit (straight and bent) |
| 15mm x 1/2" | 15 mm | 1/2" BSP | JG Speedfit (straight and bent), Conex Bänninger 303SF and 403SF (bent) |
| 15mm x 3/4" | 15 mm | 3/4" BSP | JG Speedfit (straight), Conex Bänninger 303SF |
| 22mm x 1/2" | 22 mm | 1/2" BSP | Conex Bänninger 403SF (bent) |
| 22mm x 3/4" | 22 mm | 3/4" BSP | JG Speedfit (straight), Conex Bänninger 303SF and 403SF (bent) |
JG Speedfit’s tap connectors push onto the pipe. Conex Bänninger’s 303SF straight and 403SF bent tap connectors are compression fittings. Conex gives the female threads on its compression fittings as ISO 228 parallel (parallel BSP).
If the thread on the tap isn’t marked, measure across it: 1/2" BSP is about 21 mm across and 3/4" BSP about 26.4 mm (see outside tap thread size for how to measure).
The tap end: a washer makes the seal
Conex Bänninger makes the female threads on its compression fittings parallel (ISO 228), and says joints on parallel connector threads need a good quality washer. For when a thread takes tape instead, see BSP vs NPT.
JG Speedfit’s tap connectors come with a brass swivel nut and a sealing washer, and JG Speedfit says to turn its bent tap connector onto the thread by hand. Check that the washer is sitting in the nut before you do it up.
The compression end: nut, olive and turns
A compression joint is a nut and an olive (Kuterlite and Conex Bänninger call it the compression ring) that squeeze onto the pipe. Both makers give the same first steps:
- Cut the pipe square, and check it for damage or deep scratches.
- Take the burrs off the inside and outside of the pipe end.
- Slide the nut onto the pipe, then the olive.
- Push the pipe into the fitting as far as its tube stop.
- Do the nut up by hand. Conex says to mark the nut and the pipe at this point, so you can count the turns.
- Tighten the nut with a spanner. Kuterlite says to hold the fitting with a second spanner so it doesn’t turn, and Conex says to use a flat-faced or adjustable spanner, not serrated pliers.
How far to turn the nut after hand tight differs between the makers:
- Kuterlite: 3/4 turn for fittings from 15 mm to 54 mm.
- Conex Bänninger, half-hard copper (R250): 1¼ turns for 15 mm, 1 turn for 22 mm.
- Conex Bänninger, hard copper (R290): 1 turn for 15 mm, 3/4 turn for 22 mm.
Follow the instructions for the fitting you have. Kuterlite warns that over-tightening the nut won’t make a stronger joint and could cause problems later.
Turn the water off at the isolating valve or the stopcock, and open a tap to drain the pipe, before you undo a tap connector or a compression nut.