what does this indicate, main problem was rads had gone cold, checked CH/hw controller CH was on.on boiler it self pilot light on and burning,on control front of boiler, flame green led is flashing while at the same time here a clicking sound,as this is happening the main burner will not ignite thus rads not getting warm.thermostat set to full.then 20 mins later flame led goes solid main burner ignite ,rads get warm.this will only be on for 10 mins before main burner goes off,and flame led starts flashing again and repeats the cycle again.