well, none of those suggestion will work, the damn thing was left full of
water over winter, how i dont know as i drain the system down and blow the
pipes thru with compressed air, could have a non return valve stuck i guess
and it backfilled or something, but either way, the damn thing has expanded
and cracked the solder joints.

i can see 3 or 4 cracks in the immersion heater flange solder ring, and it
deffo leaks out of some of them as i scraped the insulation off around
there,
but the whole tank has expanded enough to crack the insulation, and the seam
shows signs of external cracks,

apparantly it's a folded and silver soldered join there,

bod know if it can be fixed, the insulation will need stripping off for
sure, then i guess every fitting and all seams re-soldered, and
re-insulated,

it's about £350 for a new calorifier, which i can not afford anyway, so
looks like im screwed good and proper.