We have had the esxpansion changed on our boiler as it was constantly loosing pressure and water was spilling outside. Since having this changed we are still loosing pressure only after the heating has been turned off and it's cooling, once i put the presssure back up it will stay on 1 bar rise a little when heating first comes on but when it goes off the pressure falls quite quickly to 0. We have had all the floorboards up to check for leaks and cannot find anything. any suggestions greatly appreciated thanks
you are checking the right things, double check the pipe out side if is dripping the Pressure reales valve needs changing I would have done this any way as it will be weak if it has been running a lot.
After that that the boards up again and have another look. Good luck
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