how to drain system to change the water pressure switch

[truscott]

Hi
I have a worcester junior 28i boiler and need to train the system to allow me to change the water pressure switch. As I understand it I need to drain from the red cap (left side bottom of boiler) and drain screw under pump. Is this correct and do I need to drain from anywhere else? The pressure switch is currently by passed with a piece of wire so at least boiler works for now

 

[nickso]

don't use the prv (red cap) the drain point beside the pump will be fine but be gentle when using it, it's not held on very securely.

 

[truscott]

Hi thanks for your help there...i was only asking as the plumber showed me several points but if i can get away with just draining from the bottom screw that makes life easy i'm assuming i will then need to bleed the pump post replacement of switch?

 

[nickso]

probably no need to bleed the pump, it will sort itself out, they usually do. no harm in giving it a go if it's noisy, just be careful again as the pump washers leak for fun on these.