pex plumbing question

[jameshudson45]

My 69 Sovereign has a couple of copper water pipes that appear to be split/cracked I am assuming from not draining properly in the winter
It seems like favorite product used to repair is the pex product.

Does anyone know the recommended size used to connect to the original plumbing?
Do they make an easy connector to connect the copper pipe to the pex tubing.

 

[Puddle]

I persume with good weather you have returned to your caravan or weekend escape
The existing pipework will most lightly be 15mm,fittings from pex or any plastic pipework are readily avalible,do not use plastic pipework within 1 meter of water heater