have a ferroli optima 701,fan continually on low rate,will fire up,but fan remains on low rate,tried new fan,but still on low,pilot light seays on but when asking for demand,either heating or hot water no joy.gas valve or pcb fault?
checked and prooved air pressure switch,also,when you call for hot water,fan goes off!i thought it might be thet the pcb isnt sending signal for fan to go on to full rate,you agree?