Our radiant heat boiler tends to "flush" very loudly every night. It seems to go on for awhile too. We have three zones and I think it just happens with the one zone in our bedroom. From my understanding, this may be caused by low pressure. First, could this be a cause of this flushing or running sound in the radiators? If so, what should the pressure be or does this vary? According to our gauge the pressure is at about 25psi.
I would like to get some idea of what the issue could be before we call in someone to look at it and fix the problem. Thanks.