I have a Vokera Linea Max floorstanding in our basement. I need to drain down the CH system to replace TRV\\\'s, but can\\\'t find a drain cock on the boiler. The filling loop is connected at both ends, and there\\\'s a \\\"dummy\\\" unused pipe connected to the front plate next to the filling / inlet valve. This pipe exits externally, so I\\\'m guessing it\\\'s for drain, and that I need to swap the filling loop over to that at one end, before opening some valve to drain out. Question is - at which end do I disconnect the filling loop braided hose - at the inlet valve end, or at the other end (with the black square cock on it)?