Live wire from old pump on vented to system boiler

[rhinosaw]

Got it

 

[dilalio]

And... If the main fused (3amp) spur for the heating system is in the airing cupboard, you'll need an isolation switch near the boiler too.

 

[rhinosaw]

Boiler main switch is on the wall just near the boiler.
Aren't most isolation switches sited near the boiler, why would someone put a boiler main switch in the airing cupboard?

 

[jeff the gasman]

Boiler main switch is on the wall just near the boiler.
Aren't most isolation switches sited near the boiler, why would someone put a boiler main switch in the airing cupboard?

It’s very common.

 

[bernardgreen]

why would someone put a boiler main switch in the airing cupboard?

in case the lady of the house switches the boiler back on while the technician is working in the airing cupboard.

 

[JohnD]

If only there was some way you could remove the fuse to the boiler supply, at the switch next to the boiler....

 

[dilalio]

If only there was some way you could remove the fuse to the boiler supply, at the switch next to the boiler....

People have their boilers moved and you need local isolation for emergencies for homeowner and service personnel.

 

[dilalio]

why would someone put a boiler main switch in the airing cupboard?

Its not a boiler main switch... Its for the whole system, most of which is usually found in the airing/cylinder cupboard, so it makes sense to have it there near to the wiring centre.

 

[rhinosaw]

Ok, fair comments, I suppose there is just as much wiring in my airing cupboard as there is near to the boiler

 

[ianmcd]

Ok, that's a relief,
I blame it all on these installers coming round to give me quotes for a system boiler from a vented system.
A couple have said , have to take a wire from the old pump (in the airing cupboard) back to the new boiler.
But looks like, switched live comes from the zone valves and permanent live can really come from a live near the boiler.
I knew that I should have been an electrician really.
Thanks to u and Ian

No you are wrong, the live for the pump MUST be connected to the new boiler, the switched live from the zone valves will already be connected to the existing boiler so that is fine, the new boiler will now need a permanent live as well as the existing switched live, you will also need a system by-pass installed as you have an S plan (if one not already fitted).
The reason , your replacement boiler is low water content, when a demand for CH or HW stops the zone valves close and the burner on the boiler stops, however the boiler will still be hot and the boiler will keep running the pump to cool itself, once the boiler is cool enough it will stop the pump

 

[rhinosaw]

Now I'm confused again.
I understand that the zone valves are supplying the switched live.
But my pump must also be switched as it comes on and off with the zone valves so wouldn't supply a permanent live back to the boiler. There is no auto bypass valve so the pump doesn't stay on for pump overun, well there is no pump overun on this old boiler

 

[Harry Bloomfield]

The reason , your replacement boiler is low water content, when a demand for CH or HW stops the zone valves close and the burner on the boiler stops, however the boiler will still be hot and the boiler will keep running the pump to cool itself, once the boiler is cool enough it will stop the pump

Additionally, rather than the heat in the boiler being lost out to atmosphere, it is used in the house - adding a tiny bit of extra efficiency.