Evening all, well after much searching and interesting reading I have
resorted to my first post.
Just to be clear, my plumber is fitting my boiler but I get the
impression it has been a little while since he fitted one, so I have a
few questions.

The boiler is a grant eco vortex utility standing boiler with a sealed
system kit.

We have bought a Honeywell CMT 927 and two motorised valves V4043H.

Now plumber said that room thermostat is in the CMT 927; I get this!

However, I am not clear on whether I need a cylider thermostat; he
thinks not? Any thoughts?

Also, the CMT927 appears to be solely for controlling room temperature
(central heating on/off time) is this correct? How should I therefore
control the switching on and off of the hot water. The wiring diagrams
indicate a "programmer" is needed, so do we need something over and
above the CMT927 to control when the water comes on......or is it
instant because it is now a sealed system?

Thanks
Anthony