I REPLACED ALL MY RADIATORS AT THE RATE OF APPROX ONE A WEEK DURING SUMMER DUE TO THE RADIATORS I HAD SPRINGING LEAKS. IT IS A BACK BOILER DOWNSTAIRS WITH A PUMP IN THE EMERSION CUPBOARD UPSTAIRS AND A HEADER TANK IN THE LOFT. AFTER REPLACING EACH ONE I CHECKED IT FOR LEAKS BLED THE RADIATOR, PUT THE SYSTEM ON AND EACH RADIATOR HEATED UP FINE AND UNIFORMLY ALL OVER.
NOW I HAVE PUT ALL THE RADS ON THEY ALL HAVE A COLD SPOT ON EVERYONE WHICH IS IN THE FORM OF AN ARCH SHAPE ABOUT 4-6 INCHES IN FROM EACH SIDE AND THE SAME DISTANCE FROM THE TOP OF EACH RAD. NO MATTER HOW MUCH BLEEDING I SEEM TO DO I CAN NOT GET THEM BETTER, ANY IDEAS ANYONE ?