un-vented hot water cylinder

[hellfire]

hi all
getting a price together for unvented hot water cylinder
my supplier has recommended joule cyclone air indirect unvented hot water cylinder 250L with internal expansion vessel which is a lot cheaper than a megaflow. has anybody install one and your thoughts going to pair it with vaillant ecotec plus 637

Cyclone Air Indirect Un-Vented Cylinders - Joule

 

[ShaunCorbs]

Never used one myself but joule are spot on

I prefer external myself

Heating load kw ?

 

[Chalked]

Bubble tops are unreliable imho