STEAM HEATING PROBLEM

SCHMIDTS WHOLESALE

I WAS JUST ON A JOB SITE WHERE THE CONTRACTOR HAS REPLACED A BURNHAM STEAM BOILER WITH A EQUAL SIZE (BTU=) SMITH STEAM BOILER. WE HAVE A TWO PIPE SYSTEM, AND IT LOOKS TO BE PIPED JUST AS SHOWN ON PAGE 132 IN THE LOST ART OF STEAM HEATING, COMPANION BOOK. ON THE RETURN LINES IT HAS A HOFFMAN 31 RETURN TRAP, AND A HOFFMAN 31 RECEIVER VENT WITH A #76 HOFFMAN MAIN VENT VACUUM VALVE PIPED TO IT. I BELIEVE THIS IS A VACUUM SYSTEM, THE TYPE THAT DOES NOT REQUIRE A PUMP.

NEAR BOILER PIPING LOOKS FINE, SYSTEM IS HEATING PROPERLY.

HOWEVER IT IS AFTER THE BOILER SHUTS DOWN THAT WE ARE EXPERIENCING A NOISE THAT WAS NOT THERE WITH THE OLD BOILER.

APPROXIMATELY 5 MINUTES AFTER SHUTTING DOWN WE ARE HEARING A GLUGGING SOUND. EVERY 5 SECONDS OR SO WE GET A GLUG,GLUG. THE HOME OWNER CAN HEAR THIS UPSTAIRS IN THE HOUSE. THIS WAS NOT THERE BEFORE ?

THE PRESSURE TROL WAS SET AT 2 LBS. WHEN WE ARRIVED, WE BACKED IT DOWN TO 1/2 LB. BUT STILL AFTER SHUT DOWN WE GET THE GLUG, GLUG NOISE, AS THE SYSTEM COOLS DOWN AND CONDENSATE IS COMING BACK.

WHEN THE BOILER STARTS BACK UP THE #76 VENT IS RELIEVING AIR, THE SYSTEM HEATS PROPERLY AND THERE IS NO GLUGGING NOISE WHEN THE BOILER IS ON AND MAKING STEAM.

ANY IDEAS ?????????????

nicholas bonham-carter

glug..glug..glug?

could it be a slug of air trying to relieve the vacuum, but going through a pool of condensate in a sagging section of pipe? if you put a ball valve on the dry return, and open it as the steam is collapsing at the end of the firing cycle[ that would simulate a vacuum-breaker] the glugging should not be heard.

hope i have expressed my idea with some clarity, but it is difficult to explain. remember that the main line vents not only let the air out quickly, but also let it back in quickly.--nbc   

Jamie Hall

It does sound

as though as the system is cooling that somehow air is having trouble getting back into the mains and returns.  A true vacuum system (rare, these days!) has vents which do not let air back in -- or at least not much to speak of.  But, the air having been vented out when the system starts, it has to get back in when the system stops.



What changes in the venting were made when the new boiler was put in?



One approach which might solve the problem pronto would be to find a handy spot on the dry return where you can stick a Gorton #2 and put it on -- can't hurt anything, and might just get rid of the glug...

SCHMIDTS WHOLESALE

A REPLY AND QUESTION

NICHOLAS, I THINK YOU HAVE THE SOUND CORRECT, AND I THINK IF WE WERE ABLE TO BREAK THE VACUUM IT WOULD END THE PROBLEM. BUT CAN I CHANGE THE SYSTEM BY ADDING A VACUUM BREAKER IN THE DRY RETURN LINE WITH OUT AFFECTTING THE SYSTEM OPERATION ???

JAMIE, IT SOUNDS LIKE YOU ARE ON THE SAME THOUGHT PATTERN, BUT THE GORTON VALVES ARE AIR ELIMINATORS, I THINK, DO THEY ALSO LET AIR IN TO BREAK THE VACUUM????

AND LASTLY IF THIS IS A VACUUM SYSTEM, AND I BREAK THE VACUUM WITH A VACUUM BREAKER WILL THE CONDENSATE STILL RETURN TO THE BOILER????

THANKS GUYS, GEORGE.

Jamie Hall

Yes...

The Gortons are air vents -- but they are also, unlike the Hoffman you have, vacuum relief vents.  The condensate should still return without trouble, unless I have completely misinterpreted something (which is always possible...).  Vacuum systems were wonderful in the days of coal, when the boiler could still keep creating steam at lower temperatures under a vacuum, but they didn't rely on the vacuum to pull condensate back to the boiler; they were still basically a gravity return system.



Let me go check the Hoffman catalogue here (it's in the library) for more infor...

Jamie Hall

Here we go...

The Hoffman return trap was a neat way to avoid flooding the dry returns without having much headroom.  You have to give a lot of credit to Simpson, the guy who invented it.  Here's the library link: [url=http://www.heatinghelp.com/files/articles/1305/392.pdf]http://www.heatinghelp.com/files/articles/1305/392.pdf.

Clever, those Hoffman guys (the system in the building I superintend has a big Hoffman differential loop in it -- another one of those clever contraptions.  I'm still not sure exactly how the thing works -- but it does.).



Anyway.  Back at the ranch -- I still think a nice Gorton somewhere handy will do the job for you.  Without hurting anything.

Steamhead

Jamie's got it

you need to change the vents. Vacuum vents will sometimes hold water up in the system which then comes back slowly- and you hear the glugging.