leaking isolator valves

[kentishman]

Are isolator valves worth fitting? I ask only because every time I have fitted them, when it comes to using them for the first time after several years of not being turned, they seem to leak and need to be replaced! am I buying the wrong ones? The ones I have now that need to be replaced are from Screwfix and have a screwdriver slot to turn the valve. Looking inside them there is what appears to be a hex or allen key type socket.... can this be tightened to make them more watertight? Would a "Peglar" type with a lever be better? They on a shower pump with about 2.5 Metres head of water.
So many questions... and thanks for any advice.

 

[Goldberg]

Good quality ones are worth fitting, but a cheap one is just a plumbing time bomb.

If you're getting leaks on first use then you're not spending enough money. Screwfix are renowned for selling bad stuff for low prices.

You can't service them - the hex socket can't be used to tighten anything.

I don't know what you mean by "Pegler type". A Peglar valve would be better merely because they're good quality. Lever valves tend to be better quality, and also less restrictive because they have a bigger bore, but you can also buy full-bore spherical valves that a screwdriver slot.