Isolation Valve replacement?

HI, I`m trying to fit a isolation valve to a basin tap but when trying to tighten the nut to the valve with the olive in between on a 15mm pipe, seems far to loose on pipe, and just comes straight off. Any advice anyone please ??

Sarah (trying to save money)
May 2011

many thanks rawplumb

Don
November 2010

Short answer is yes, also valve you talk of is not designed for heating systems as is not full bore, better to cut it out all together or replace with full bore valve which won't restrict flow round a heating system.

RAWPLUMB
November 2010