Replacing 2 zone valves in CH system

[ACDC]

I want to replace the 2 zone valves in my CH system. (Preventative maintenance; it's summer-time and they're 17 years old.)
The problem is that I've slackened off the compresssion nuts, but there is not enough movement in the pipes to enable me to remove the valves. I've undone all the pipe clips, still not enough room. Any ideas?
ACDC

 

[D_Hailsham]

If they ain't broke, don't fix it!

 

[ACDC]

But I've bought them now and I like doing it!

 

[gasafengineer]

Sometimes it's necessary to remove pipework upstream/downstream of valves via cylinder unions/valves , you may find removing the pump will allow enough movement to remove the valves.

 

[ACDC]

Thanks gasafengineer. I was considering cutting a small section out of the pipe just below one of the valves to give me some slack and repairing it with a straight compression joint. Does this sound OTT?

 

[gasafengineer]

. Does this sound OTT?

Not if you're sure there is no other way.

 

[MrGassafe]

Thanks gasafengineer. I was considering cutting a small section out of the pipe just below one of the valves to give me some slack and repairing it with a straight compression joint. Does this sound OTT?

I you havn't enough slack to remove pipe from under valve how do you
propose to pull pipes apart to fit a compression coupler?

If your valves are honeywell then why not leave in place and replace the guts and actuator.