montasser charni
Hi Stuart The system pressure should be usually about 1 bar or 1.5 bars when cold it can increase to over 2 bars when the heating has been on for a while ,then it should go back to the original pressure when cold. Your description suggests that your heating system must had lost water .And that must be investigated it can be caused by a leak or if the system is a sealed one prom ably a problem with the expansion vessel ....etc just to mention few . As mentioned above an investigation also what time of system ..will get to the bottom of it . I hope all the above helped giving you a broad idea . Regards
