If the existing cylinder has sprayed on foam lagging the main reason to replace it is to benefit from the greater heat input and faster recovery time.
If the old standard coil is fitted then a modern boiler will be cycling and much ofd the condensing advantage will be lost.
Its not compulsary but just advisable.
I tell clients that if its copper it MUST be replaced, if yellow foam its better replaced but if green it would be better but not very necessary and if its blue its OK to keep it.
For a retired couple its not very inportant if it takes longer! For a family of five it is !
Tony
If the old standard coil is fitted then a modern boiler will be cycling and much ofd the condensing advantage will be lost.
Its not compulsary but just advisable.
I tell clients that if its copper it MUST be replaced, if yellow foam its better replaced but if green it would be better but not very necessary and if its blue its OK to keep it.
For a retired couple its not very inportant if it takes longer! For a family of five it is !
Tony