saunier duval combitek f23e water leak?

Our saunier duval combitek F23E is leaking water from below the unit. The pressure is at about 0.75 bars. There wasn't a leak a week ago when we turned off the water while we were out of town. When we returned, we turned on the water again and now it is leaking. We read in other forums that the leak might be caused by low pressure, but we're not sure how to fix it. We've also downloaded the manual, but haven't found any trouble shooting tips yet. Any advice? Thanks in advance for any tips!