My ECM Giotto works fine, but after a few hours of being on the pressure gauge will go up to 1.7 bars, and steam comes out of the relief valve. I thought it was the pressure stat and replaced that. It was ok for a bit, and then starting doing it again. If I reduce the pressure with the steam arm it seems to be fine for a few hours. The boiler doesn't get hot enough to click off the high limit. It just steams away
Is it my pressure relief valve?