Tap tails and isolation valve roblem.

[steadyon]

1. The isolation valve you show is a 15 mm isolation valve. It has 1/2" BSP threads and compression nuts at each end, NOT 15 mm nuts.
2. The Amazon tap has what looks like 3/8" BSP nuts at the non-tap end. If this is correct, then to fit it you will need:
2a. The Screwfix 3/8 adaptors already mentioned in post #2 or the Toolstation equivalents quoted by JCPlumber in post #5
2b. A nut and olive to fit each isolation valve. I'd suggest you just buy another 15 mm compression isolation valve and use the nut and olive off each end on the existing isolation valves.
2c. fit the nut and olive onto the adaptor. Insert the unthreaded end of the adaptor into the isolation valve and do up the nut. Do the nuts up with a spanner. Tighten just enough to stop the adaptor being able to turn, then another 1/2 turn on the spanner.
2d. Screw the 3/8" end of the flexi onto the threaded end of the adaptor. Tighten up firmly by hand, then a bit extra with a spanner. There should be a rubber washer inside the flexi end, and this makes the seal. It only needs to be nipped up tight enough not to leak.
3. The B&Q tap clearly has 1/2" BSP female threaded ends. To fit these, do as 2. above, but use the other (1/2" BSP)
quoted adaptor.
4. NONE of these fittings are push fit.

 

[rpm]

Nice explanation there Steadyon, I might just add to use a 6 or 8" long adjustable spanner to hold the isolation valve firm when tightening the new nut and olive of which I would a copper olive not brass olive.

 

[SimonG]

£400.00 pound not sounding so rich now.

Appreciate the personal circumstances but this a real good indication of just what a professional brings to the table.
Not just materials and time, but knowledge.

And as you are learning, the knowledge is priceless.

 

[woof woof]

Thanks steadyon.

I've just googled the BSP thread sizes and now I see why I've been confused on the measurements.
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rpm

Yes, I've used a spanner on the isolation valve every time.

Simon.
I appreciate that plumbers have knowledge and deserve their money. I served my time as an electrician before moving into computers where I worked very long stressful days for very long stressful years so I do know about hard work and long hours and being paid what you're worth.

I stopped working 10 years ago to look after someone with a few issues including alzheimers and I've not undertaken paid work or taken a penny off the state since and had precious few days relief in those 10 years so sorry but I make no apologies for trying to save a few £ here. If the guy had quoted £200 and explained why I'd have paid the money and sucked it up but as it is I'll thank you all again and see if I can get this done on a budget that leaves me some money for the next little maintenance job. It is that tight.

Thank you all and goodnight from a grateful me.

 

[Leonardo]

1. .....screw directly onto the isolation valve, although this is not good practice, its better to have a piece of pipe or an adaptor (e.g. Screwfix 2665R) between valve and flexi.

Genuinely looking to learn/explore.

Whats the reasoning behind this?

Why is it not - good/best practice to screw directly into an iso valve?

 

[Ben-gee]

Because the isolating valve has an end designed to accept an olive, as such it tapers to a very thin edge. The washer in the flexi therefore has a very small area to seal onto, not only that but over tightening can easily cut into the washer.
The adapters mentioned above have a wider area to seal to and this is machined flat so will not cut the washer.
In practice there must be millions straight onto the isolating valve and often no problem occurs, but the above is considered best practice.
(The adapter is relatively new to our market and can be substituted with a male iron, which is what was used previously)

 

[RayW]

Or use a flat face isolation valve. ... Flat Faced Straight Lever Op. Isolation Valve 15mm x 1/2 - https://www.bes.co.uk/flat-faced-straight-lever-op-isolation-valve-15mm-x-1-2-bsp-pm-25058/