Pump overrun query

28 Jun 2009
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United Kingdom
Has anyone got the Honeywell wiring booklet/guide? I downloaded it.

The wiring for a S PLAN with pump overrun doesn't make sense, the reason I say it is :

the boiler has a NEUTRAL and EARTH connection as normal, a PERMANENT LIVE to it, and still has the switched live from the ORANGE WIRES to it. The boiler provides LIVE to the PUMP via a separate terminal block. My point is: how does the pump run?

Pump overrun stats make when the temp is over 60 degrees C and open when the temp is under, so when the boiler 1st starts up, and the water is a lot lower, does the pump not run ??? .....
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When the Boiler is Cold, the Pump is fired via the SwL terminal, it works like this,

Over heat Stat Common = Pump Live
Over heat stat Norm Open = Perm L
Over heat stat Norm Closed= Sw L

therefore when cold pump is fed by SwL, once hot feed transfers to Perm Live, untill boiler stops and cools down

Simples ;)
I see, so the switched live to the boiler, also feeds the pump as well, via the boiler....

A lot of newer modern boilers with internal pumps, like combi's, the pump is part of the firing sequence and controlled by the PCB isn't it.

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