I HAVE ADDED AN EXTRA RAD TO A COMBI SYSYEM I SPERED OFF AN EXSISTING ONE VIA THE LOFT THERE WAS ONLY 4 RADS BUT TWO SETS OF BOTTLE VENTS ONE AT THR REAR AND ONE SET AT THE FRONT OF A SMALL BUNGALOW HAVING RE CHARGED THE SYSYEM AND BLED IT ALL SEEMED OK THEN AFTER A COPPLE OF DAS ONE OF THE VENTS ST...
