waterlogged boiler skim line trap

remagen

Good evening. i have a very confusing problem. I have a customer who has 2 Pacific steal tube steam boilers. somtimes they run one, sometimes two. header valves must remain open. naturally after a weeks time the boiler that is off line overfills gradually.

I installed F&T traps 2to3 in. above the normal operating water level. when one boiler is running and the second is off line. the one off line approaches  the level to start skimming it starts a horrible water hammer and the level line starts bouncing to the slugs of water subjected to the F&T.  the boiler has a McDonellMiller no.61 on the left hand side. I simply extended the cross fittings and formed a 1in. column between the 2 points seperating with a tee using the same steam supply and boiler water level fittings. the bull of the tee is the level at which I`m trying to skim. If I manually lower the level and subject the f&t to only steam it operates just fine. If I manually over fill to the top and then open the valves to the trap it drains off just fie untill the live steam interacts, then same condition. I have no idea what else to do. I`ve done this on ther boilers and it worked fine. the make up is pumped in the rear of the boiler at the base so there is no hartford loop or equalizer line. no ides what else to do....