Adding an additional zone to existing heating system, should this work?

So iv got to add a mini one UFH zone to an existing property's heating system, i have already wired in all the easy parts ie. actuator, zone valve, stat etc. however i just need to hook it up to trigger the boiler. iv attached a few images to try and explain things better, the plumber told me not to ring 'NU Heat' as he claims they are useless, however i rang them anyway and the technical help line stated that all i need to do is supply a permeant live to 'boiler enable in' and take 'boiler enable out' on to the switch wire of the boiler. (which iv drawn in pink below) which if this is the case its a piece of cake. however my main concern is will this work properly with the other 3 zones already in place. (ground floor ufh, Hot water, and upstairs rads) i was lead to believe in some situations a relay is required but the Nu heat tec doesn't seem to think this is needed, if anyone is able to cast an opinion on this would be great.

More info The new 1 zone is for a kitchen extension, the wiring centre for it will be mounted in the kitchen cupboard where the manifold is, i was going to supply the L-N-E-SL directly from the outside boiler which backs onto the kitchen wall, and fit a triple pole switch in the cupboard. The SL from the new manifold will be doubled up inside the boiler with the existing SL.

Thumbs up for the Nu-Heat Tech. The existing valves and UFH Manifold operate as relays as does the single zone unit.

The existing zone valves should all have grey and orange wires, all going to the same terminals in the wiring centre. Connect a 2 core wire between these terminals and boiler enable on the UFH board.
If the same isolator doesn't switch off boiler and UFH, a warning of two supplies should be added to the UFH board cover.

DefyG said:

Thumbs up for the Nu-Heat Tech. The existing valves and UFH Manifold operate as relays as does the single zone unit.

Click to expand...

Glad to hear this should work.
Just interested to know in what situation would you need to use a relay, I know iv worked on systems before that have had them to stop certain zones operating at the same time but if I'm honest i don't know why some systems are like that and others are not?

brianmoooore said:

The existing zone valves should all have grey and orange wires, all going to the same terminals in the wiring centre. Connect a 2 core wire between these terminals and boiler enable on the UFH board.
If the same isolator doesn't switch off boiler and UFH, a warning of two supplies should be added to the UFH board cover.

Click to expand...

Grey to Boiler Enable 'In'
Orange to Boiler Enable 'Out'
That's how i understand it. I'll make sure its on the same circuit, its easy enough to do and there's no chance of interconnected Neutrals tripping the RCD.

When I install anything like this, I always spend an hour or two of my own time tracing out the full internal wiring diagram of these boards aimed at plumbers. Helps me to understand exactly how things work, and is invaluable when things go wrong in the future.
That complicated looking board for the original UHF system is actually very simple when you've traced it all out.