Grohe Tap Tails issue

[lancs_lad]

Just bought a Grohe Kitchen tap. The description states 1/2" BSP tails but measuring across the connector they're 7/8". I'm struggling to find a male connector from a 15mm pipe, any suggestions please? Really helpful guy in local Screwfix was stumped.

 

[CBW]

Have you actually tried a 1/2” connector? You could be measuring it wrong.

 

[Rodders53]

Grohe tails are either 1/2 inch or quite often the smaller 3/8 inch in my experience.

Adapters are available to 15mm compression: https://www.toolstation.com/tap-tail-adaptors/p63663

Never heard of a 7/8 inch size myself - was that a typo?

EDIT You can also get threaded adaptors from 1/2 down to 3/8 if you search.

 

[plugwash]

The nominal size of BSP threads bears little relation to the actual measurements.

 

[lancs_lad]

They're definitely not 3/8" I'll have to visit a plumb merchant I think. I'n replacing a Franke tap that has different sized tails which has caused the issue.

 

[Rodders53]

Which Grohe tap model from which supplier?
The specs may tell all...

 

[CBW]

Can you post a photo of the tails in question?

 

[lancs_lad]

https://www.screwfix.com/p/grohe-ambi-dual-lever-mono-mixer-kitchen-tap-chrome/317jj 1/2" BSP female thread it states but they measure 7/8" which is what threw me.

 

[terryplumb]

Have you got any isolation valves on the supply pipes to tap ? The thread will be 1/2 inch BSP on your new tap tails. The thread size has nowt to do with the diameter.

 

[Rodders53]

The Grohe install leaflet has both 1/2 inch or 3/8 inch mentioned.... The leaflet has a vague 24mm (? the across flats of the nut?) on one diagram.

https://www.grohe.co.uk/en_gb/ambi-two-handle-sink-mixer-1-2-30189000.html only mentions the 1/2 inch and an adapter for 'continental use'.

Pics of the Franke tails and pipe connections plus the Grohe as well would likely be of some help - with a ruler for scale, perhaps?

 

[lancs_lad]

The 1/2" BSP fit thanks (should have believed the spec!). Anyway thats sorted and will use the push fit on both sides which will make for easier fitting as I can attach them to the tails before fitting them and save messing with spanners in a confined space.

 

[plugwash]

To expand on my earlier comment, my understanding is that BSP sizes were based on old-fassioned iron pipes. Such pipes were measured by a nominal internal diameter and the thread was cut into the outside of the pipe. So the actual size is a lot bigger than the nominal size.

1/2 inch BSP is the same size as the compression nuts on 15mm compression fittings.

 

[lancs_lad]

Yes the vagaries of imperial measurements.