I have had a quote for a boiler system to be installed. There is about a £200 difference between two companies. The main difference is the boiler. The two makes are; Glow Worm Flexicom 24kw condensing combi boiler and Vokera Unica 32HE. Both companies are proposing to use 'push fittings'. Which boiler is best of the two?[/b]