Heating Help

Water in Sight glass on steam boiler goes down 1 1/2 inch a day

Hi, I have a question my pennco 1660 hsd steam boiler, one pipe system I notice the water level in the sight glass goes down about 1 and 1/2 inch a day which causes the water feeder to kick in and bring it to regular level. I'm worried this is not normal and am not sure what to do. The heat works fine and all radiators heat well. I do not see any leaks or water around radiators or boilers. Last year I had return pipes replaced. If anyone can advise me on what I can do. Thanks. V

disappearance of water

if the water never comes back, then it must have gone somewhere. underground leaks are not readily visible,
if you look at your chimney, while the boiler is firing, can you see steam?--nbc

Are you sure

Short cycling due to moderate weather will cause a slow water return. Are you sure the feeder is coming on or does the water just return as it should?

Waterline gets lowered

See if you can valve off the water-feeder, and see if the water is indeed disappearing over a few days. That would point to a leak, instead of slow returns.--NBC