Hot water, central heating and separate pipework

[DeusXM]

Bear with me as I'm a complete idiot on this stuff.

Setup:
Ancient Potterton Profile 60e boiler downstairs
In the loft, there's a hot water cylinder, what looks to be an expansion vessel (it's got a gauge on it, and pipework that can be used to add water), and then a small white tank that looks like a expansion vessel but doesn't seem to have a pressure gauge, and has a label saying its a Zilmet Ultra UV HT Pro.

Questions:
Does this mean I have a system boiler?
Does that mean the pump is inside the boiler, rather than a separate external component?
I'm guessing the expansion vessel is what's used to pressurise the central heating...so what's the Zilmet tank for?

Then some more random questions:

Previously, my mains supply pipe connected to a pipe under the kitchen floor, with a stopcock just before a pipe that goes up inside the kitchen wall, by the boiler. Recently I had to have my supply pipe rerouted as the kitchen floor pipe was leaking and inaccessible. So I've had a new stopcock put in, the old one has been turned right off so the old kitchen pipe is no longer carrying water.

When the boiler is 'on', hot water out the tap is now really, really, really hot. The rads, however, are lukewarm at best. I know I need a powerflush anyway, but the rads have gone from being pretty warm with a cold sludgy bit at the bottom, to just slightly lukewarm with a cold bottom overnight.

Meanwhile, the towel rail in the upstairs bathroom is ice cold - even the pipes leading into it. It wasn't like this before the supply pipe was rerouted.

Questions:
I've bled all the rads and there's no air in them. I've also repressurised the system. Cany anyone suggest a reason why changing the supply pipe entry point might cause the central heating to drop in temp...but the hot water stay really, really hot?

I've realised that the towel rail is directly above the vertical pipe in the kitchen that's now been capped off. Is is possible that the towel rail has actually been piped in to the hot water rather than heating pipework, and that capping the supply pipe has blocked off a hot water pipe?

 

[oldbuffer]

1. No. The Profile 60e is a heat only boiler.
2. So no, the pump is somewhere else.
3. If its white, the expansion vessel will be part of the unvented hot water system, not the boiler.
4. The boiler can be fed from a feed and expansion (F&E) tank, normally in the loft. OR
5. It can form part of a sealed central heating circuit, in which case there will be a (probably) red expansion vessel somewhere, with a pressure gauge, filling loop, and pressure relief valve discharge pipe (15 mm copper) to outside.
6. No one can tell from here where your pipes go or how they are connected. Either an accurate and complete diagram or a set of photographs might make it possible to advise on the other problems.
7. For the hot water cylinder to be in the loft it is almost certainly and unvented ("UV") hot water system. The require an annual service for safety reasons.
8. The boiler also should be serviced annually.