i have a 3 year old ferroli maxima 35c my problem first started a week ago when my shower would hot then cold then hot then cold and now my radiators are only luke warm the boiler keeps starting up and then shuts down it is as if it thinks the heating is up to temp and then stops then knows the water on the heating needs heating up comes on again then stops again .my hot water from the taps runs hots then cold hot the cold ?? any ideas maybe senors prob or printed circuit board i need some help