Rafal Kaczynski
Dear Susie If water is being discharged from the pressure relief valve( boiler overflow), this may mean that the pressure relief valve is faulty. Another case of discharging water from a boiler can be caused by faulty Expansion Vessel ( splitted diaphram )or lack of pressure in a Vessel so it means will required recharging( by gas engineer only I am affraid) In either case, if your heating system keeps losing pressure you should do one of the following to get advice or help: contact your installer or any gas safe engineer as a work on a gas boilers can be carry out by Gas Safe Engineer only. I hope this can help Regards Rafal
