It might be due to too little water in the tank, hence too little pressure. Is there a pressure gauge and is it reading/showing below the operating range? If so, you might find a small lever underneath (or somewhere else on the unit) which needs to be turned OPEN for a short time while you watch the pressure build back up to its normal range. My unit is a different OEM however it is also an Italian brand and therefore might be sharing some parts. Try using this info to see if you can resolve your problem. I know you must have done so already since it is years later now Maria, but in case other users come here with the same problem. :-)
a noble soul, December 2016
