AFAIK you have to get a condensing one, now, BR
We just got a Worcester 'Greenstar 28i junior' & very nice it is, too - we did it the expensive, but easy, way and got British Gas to fit it, though.
Ironically, the one it replaced, you may remember, is the same Vokera as yours - after 15 years good service, so if this new one gets near that, I'll be pleased
