Yes it does and I'm afraid that replacing a cylinder is now notifiable work irrespective of whether its vented or unvented. If you are going unvented you'll need a qualified plumber (he doesn't have to be an RGI) with a G3 ticket. For vented unless you are able to self certify then you must get Building Control involved if you plan to do it yourself.
Sorry for delayed reply. The truth is that Part L1B doesn't actually stipulate that you MUST upgrade to fully pumped so PB is strictly correct. However, it advises that you should upgrade and I would consider it good practice anyway. So I always advise peeps that they should upgrade. Its actually up to them to take that advice or not.
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