Check alternator ind wire is connected. When you measured 14.2 volts were you revving the engine fast?
We've got a 147 JTD and when my alternator packed up the car would go to work and back, about 15 miles and then I would have to charge the battery up again. That was at Christmas when I was having to drive with all the lights on and heater fan as well. It got so bad that only the engine carried on working, even the dash lights went off to try and keep the engine going, no lights,indicators etc. Occaissionally the alternator would charge at about 2500 revs before it gave up the ghost.Have you left a charger on the battery overnight since you got the new battery by any chance, this may explain the premature failure of your replacement battery?