You generally find when you increase the temperature of an elecrtric shower, that the pressure does drop. However, I wouldn't say that it should be significantly so. You should contact Modern Plant, who are the supplier of Mira showers in Ireland. Their phone number is 01 459 1344. You could talk to somebody in the technical department and see what they say, they could also arrange a service call for you, this should be free of charge if it is down to a manufacturer's fault. However if there is no fault with the shower itself or the problem is due to how it was installed, they will charge you a call out fee. Hope this is of some help to you.