Hi does any engineer know where the leak is most likely coming from on a Worcester 30si it's dripping from underneath main heat exchanger and expansion vessel is this a common fault cheers.....
Have you recently had the system topped up? Does it have a detachable filling loop?
have you had a look with a torch and dry paper towel?
best to wipe it all dry then sit, watch and wait, you should be able to trace it back to its origin.