3 Nests, Boiler, Megaflo and UFH - wiring assistance

[AJshep]

Sure the "Nest Engineer" knows how RCBOs work and will fix it in no time, so I wouldn't panic too much.

We used to do alot of of heating wiring for school boiler rooms, quite often we would have a 16amp circuit with a isolator Clearly Labeled" near the Boiler to completely isolate the supply and control gear. We then put in inividual fused Spurs for pump and boilers which we could fuse down accordingly, reason we would do it like this is because some of the pumps were pretty big.
I enjoyed it though as got to do a fair bit of metal conduit and play with some relays. Most things are done with PLCs now though.

 

[davesparks]

As far as I can tell there are 2 x 3 core and earth (1mm) running from the wiring centre in the loft to the wiring centre by the ufh heating manifold. I assumed (incorrectly?) that this was to be used for control rather than control and power to the manifold/pump downstairs?

The one saving grace is that if it is wrong it's still possible to get a cable from the loft to the utility room if required.

Usually only one 3c&e cable is required between ufh manifold and boiler for both power and control.

 

[davesparks]

The Nest heating engineer wired up the nests to control the ufh heating zones and that all appears to work as expected (nest 1 opens 4 actuators, nest 2 opens the next 2 etc). His issue arose when trying to switch on the boiler from the ufh wiring centre. I shall double check with him today that he's all good for the weekend and that he's confident everything will be wired correctly (and work as expected).

Nest engineer? I thought you said earlier that you used a nest pro installer?
Nest pro installers are anyone and everyone who wants to sign up for it, no qualifications or knowledge are necessary. I would say that based on what has happened the one you have employed hasn’t got a clue about electrical installation work or electrical safety.