I have a two-bathroom four-bed house (with hydro UFH on GF and rads upstairs) and have decided to go for a storage combi. Realise many prefer an unvented cylinder system, but i'm sure a storage combi will be fine for my needs. The Vaillant 938 has been suggested to me, but i was wondering if there are any alternatives i should consider, e.g. Worcester or Viessmann etc.