Steam boiler water level problem

RonNE

Having a problem w/ an old steam boiler, water level keeps rising w/ feeder on and drops too low w/in a couple of days if shut off. Not leaking by nor is bypass. The tankless coil has been disconnected back along. The piping is all visable, only a couple of small drips near boiler. Now this is about a 30 year old boiler that we are going to replace in the spring I just need to keep it going for now with a proper water level. There isnt any equalizer nor Hartford loop on the boiler and its the first time I have seen one piped this way, simply returns into bottom of boiler, and w/o check valve. Could this be causing water level problem, hard to believe so with the age of system, not sure? Thanks for replies

Barbarossa

Your water level

First guess is the differential pressure can be pushing the boiler water back into the return then the feeder adds more. Eventually a overfill is evident.

[Deleted User]

Check for a restriction

in the feed water piping where it enters the return. It's possible the unit is feeding when required & w/ a restriction, the pressure on both sides of the V&S equalize and holds the seat open. A broken union test won't show this one.