water hammer in morning and evening

smg51

I'm servicing a 2 pipe steam system that hammers in the early morning and late at nite. It runs fine during the day. One end of the home wasn't heating well. I traced the piping and found the main and return drips were above the boiler waterline. The boiler was replaced 4 years ago and the contractor missed this. The home owner said the problem ( not the water hammer)  has been around since then. I lowered the drips below the boiler water line. Fired boiler, this loop actually had heat for the first time in 4 years. Problem solved? NOT YET. i got a call next morning about the water hammer. There are 2 indirect units for the living room on this loop as well as the 2nd floor master bedroom, first floor foyer radiator, My guess is the traps are bad on all of these rads, Now that the return is no longer pressurized i'm guessing steam is entering return and flashing the condensate left in the piping from previous cycle. Evening and morning. The steam fleshes the sitting condensate pushing it thru, during normal cycling during the day system works ok. I didn't ask but guessing customer sets stat back in the evening accounting for water hammer in morning when boiler has longer cycle?  I would appreciate feedback, comments, THANKS SMG51

Jamie Hall

Sounds like...

you're on the right track there.  The evening one is a little harder to figure -- but no impossible: it is possible that the boiler isn't running all that much during the day, depending on temperature and sun load.  Water hammer is sometimes much worse -- or even occurs only -- when the system has been sitting cold for a while.



Probably do have some iffy traps.  Easy to fix.