vailant and gloworm design are near identical heat engines, but build quality shines through on vailant. (crappy glow worm keeps me in a job)
Ideal crap I permanantly keep a set of pcbs on van as that is prob 70% of time,
worcester have fallen in my opinion, they are a swine to strip and the junior model is a bag of crap always locking out for ignition faults (note frozen condensate appears as an ignition fault just incase anyone was coming across it in cold snap)
Not really seen any of the alphas with the new warranty but would like to
Potterton and baxi are ok nothing special the new solo has a fault on the ignition arcing to the combustion door but other than that the baxi's are ok
overall I like vailant best which is what i will replace my own with in summer, easy to service install repair and most important in my opinion parts are very easily obtainable due to vailant trying to make generic parts to fit the entire range. just don't tie yourself in to their ebus control system, stick with what works.