Had to get a new pump fitted on the central heating / hot water system and the plumber fitted a new Wilo Yonos pump, but when he left he had the red turn knob on the pump set to the bleed function, i would never had know this only we where getting this surging noise and thought i would investigate further so what should it be set to, the system is in a two story house with 8 rads.
http://www.wiloszer.hu/user/YONOS-PICO/WILO-YONOS-PICO-Manual.pdf
http://www.wiloszer.hu/user/YONOS-PICO/WILO-YONOS-PICO-Manual.pdf