New Tap Tails Don't Fit Pipes

[markjg123]

I've just but two Hansgrohe Vernis taps to replace some grubby existing taps, but the flexi pipe tails have a smaller connector than the existing ones. The new ones are 15mm and the existing ones roughly 20mm. Is there a simple way to connect the 15mm tails to the existing isolator valve? The pipe tail in the photo is the old one.

 

[gas112]

the existing valve in that picture is a 15mm valve

 

[denso13]

Possibly 3/8" tails, change the valves for these https://www.toolstation.com/flat-faced-male-straight-isolating-valve/p38483

 

[markjg123]

Possibly 3/8" tails, change the valves for these https://www.toolstation.com/flat-faced-male-straight-isolating-valve/p38483

The supplied manual does say 3/8.
Really dumb questions coming up:
1. Is the other end the new valve you suggested the same size as the one I'm replacing?
2. Is turning off the water supply at the stop cock enough before removing the existing valves?
3. Do these valves require PTFE tape on the thread?

 

[markjg123]

the existing valve in that picture is a 15mm valve

Why don't the new 3/8 tails fit?

 

[denso13]

Yes for 1 and no for 3.

If a combi then the stopcock with turn of both hot and cold, if something else you may need to run the hot tap until it stops. Turn off the stopcock and see what happens.

 

[denso13]

Why don't the new 3/8 tails fit?

Because 15mm is bigger than 3/8".

 

[oldbuffer]

1. Many plumbing fittings (but not pipes!) are still imperial, based round the nominal internal bore of the pipes they were designed to suit.
2. Thus you frequently get 1/2" British Standard Pipe (BSP), 3/4" BSP. You can also get, as you have, a continental manufacturer using 3/8" BSP.
3. The BSP threads come in two flavours, parallel (BSPP) and tapered (BSPT). The parallel threads are usually referred to as "G" something, such as G1/2
4. The easiest solution in your case is to get a pair of adapters, such as Screwfix Item No. 6089R. Fit the plain end into the existing isolation valve and the end of the flexi hose onto the the G3/8 screwed end. Saves changing the isolation valves. You will also need two nuts and olives for the currently open end of the isolation valves. . Easiest way is to buy another isolation valve (e.g. Screwfix Item 65251) and use the nuts and olives from one of them.

 

[markjg123]

1. Many plumbing fittings (but not pipes!) are still imperial, based round the nominal internal bore of the pipes they were designed to suit.
2. Thus you frequently get 1/2" British Standard Pipe (BSP), 3/4" BSP. You can also get, as you have, a continental manufacturer using 3/8" BSP.
3. The BSP threads come in two flavours, parallel (BSPP) and tapered (BSPT). The parallel threads are usually referred to as "G" something, such as G1/2
4. The easiest solution in your case is to get a pair of adapters, such as Screwfix Item No. 6089R. Fit the plain end into the existing isolation valve and the end of the flexi hose onto the the G3/8 screwed end. Saves changing the isolation valves. You will also need two nuts and olives for the currently open end of the isolation valves. . Easiest way is to buy another isolation valve (e.g. Screwfix Item 65251) and use the nuts and olives from one of them.

I'm wishing I checked this before buying the taps. The instructions show G3/8 (see photo), which I thought meant 15mm internal diameter. The valve says 15mm too but the external diameter is nearer 20mm when I measure it.

 

[denso13]

The instructions show G3/8 (see photo)

Very common, I'd change the valves, but there are options.

 

[markjg123]

Very common, I'd change the valves, but there are options.

If you look at this photo then it looks like the pipe has PTFE tape under the valve. Why?

 

[denso13]

Someone who didn't know what they were doing? Who knows.

 

[markjg123]

1. Many plumbing fittings (but not pipes!) are still imperial, based round the nominal internal bore of the pipes they were designed to suit.
2. Thus you frequently get 1/2" British Standard Pipe (BSP), 3/4" BSP. You can also get, as you have, a continental manufacturer using 3/8" BSP.
3. The BSP threads come in two flavours, parallel (BSPP) and tapered (BSPT). The parallel threads are usually referred to as "G" something, such as G1/2
4. The easiest solution in your case is to get a pair of adapters, such as Screwfix Item No. 6089R. Fit the plain end into the existing isolation valve and the end of the flexi hose onto the the G3/8 screwed end. Saves changing the isolation valves. You will also need two nuts and olives for the currently open end of the isolation valves. . Easiest way is to buy another isolation valve (e.g. Screwfix Item 65251) and use the nuts and olives from one of them.

I'm sure I have nuts in a bag of plumbing spares but not olives. What size olives do I need?

 

[denso13]

15mm.

 

[thomp1983]

For me I'd fit 2 of the below,

Flat Faced Male Straight Isolating Valve

This flat-face valve provides a flat face for flexible hoses with swivel nuts. This protects the hose washer from damage and prevents leaks. Also available in 1/2" (code 95064) and 3/8" (code 38483) sizes.Angled valves are also available (code 31424) and (code 53270).

www.toolstation.com

Turn your water supply off, run a tap to remove most of the pressure, use the exiting Iso valve to drain the pipework, undo the lower Iso nut remove the valve, refit the new valve using the existing nut and olive on the pipe, I'd likely put a couple of wraps of gas ptfe round the olive on the pipe for safe measure.

New tails will then go straight onto the end with new rubber washers.