zero pressure governor / system boiler ?

[jakerobinson]

couple of quick questions that've been bugging me...

1) does a zero pressure governor in a boiler replace the air prssure switch or fan thermistor, to prove the fan is operating correctly, before ignition takes place. are zero pressure governors common nowdays?

2) does a system boiler (pump inside casing) have the l n and e from the pump wired up via the wiring centre like a normal system or is it pre-wired into the boiler's pcb and stats when the boiler gets its switched live?

 

[Rob]

1)Some boilers with a Zero Guvenor still use an APS. Worcester use it in reverse.

2) The boiler pump is wired to the board. So typical wiring would be Permanant L-N-E and a S/L.

 

[jakerobinson]

ok i see, so the boiler is wired up in the wiring centre as normal (L N and EARTH), and the pump has a swtiched live, from the pcb to it, which will already be wired by the mfr...?

 

[Rob]

No its a permant LNE. So the boiler always has power. For various reasons.

The S/L comes live when a demand is made and fires the boiler up.

The pump is just another part of the boiler sequence.

 

[jakerobinson]

ok i get you now, the boiler has a permanent feed instead of a switched live from the wiring centre, and the pump operates when the boiler tells it to, ie from the pcb... no wires from the pump to wiring centre.

 

[gas4you]

No, as Rob has said, the boiler has both permanent live and switched live to it.