How to isolate a tap?

[mivec]

I have a pressurised hot water sytem and want to change the shower and taps. There are no isolator valves fitted so is there any way of isolating these fittings on such a sytem save for turning the mains off or fiiting valves?

[stoneyboy]

mivec,
Turn off the mains, depressurise the system and fit service valves at either strategic positions or adjacent to every tap/shower you replace.
end

[mivec]

[quote="stoneyboy"]mivec,
Turn off the mains, depressurise the system and fit service valves at either strategic positions or adjacent to every tap/shower you replace.
end[/quote]
Thanks for your advice.