alternating reciever

mike terry

I have been working on this old 2 pipe steam system in a school.The first boiler was coal fired.The replacemant boiler is gas fired. theres about 1800 square feet of edr in the form of large convectors.the boiler size is about 750,000 btus input.the boiler has been floodingabout every week.the water level keeps creeping up even with the feed valve shut off.Its not went off on low water yet.goes off on high water.the pressure was set to cut out at 10psiwith abt1.5 diff.I lowered the pressure downto 2 psi with good results.but the boiler would build pressure and sit there...no steam moving. so i wentto the end class rooms.By the way there is a main on each side of the building. one main ends under a restroom. and the other under a classroom. In the class room i found a vacuum breaker and in the bath room there was a nipple and a cap that was real easy to remove...well the steam was on its way seemed like evry convector in the school heated at once. i couldnt help myself but to put a big vent on the end of each main.As you can imagineits quite impressive on start up. the teachers do not share in my enthusiasim.ANy how i have not heard or felt any air coming out of the air eliminator trap that is tied into the return piping as well as the boiler return trap. whats a guy to do if that thing is bad? other factors such as the inboard check and the outboard check are piped at the same level, is that ok? And another thing the hieght to the center of the gauge glass is about 35",the hieghtto the top of the check valves is about 45".The water line bouces wildly. dont know if its the piping on the return side or the fact that whoever changed out the boiler only used one tap.to look at it there no way its not carrying water out with the steam.Which brings me back to the nasty reality at the ends of the mains.Everything im reading is telling me that more than likely theres some sorta thermostatic traps at the ends to deal with allthis air im pushing out thru those vents i put on the end convectors.I also wonder do i need that vacuum breaker. it runs with out it, and there is a nice big compound gauge on the boiler.i put regular #75 vents on so they aint holding a vacuum anyway.So if these vent stay on the job should they be a differant type? I realize these are just band aids on a broken leg.And i would say ive got a bad convector trap or two or 17. All this stuff is dunham.So thats about it,...the problem with getting to the end of the mains is a small scary pipe chase...not to mention the danger sign on the wall warning of asbestos.all the pipe insulation in the boiler room has been replaced.Any help will be greatly appriciated... sorry cant spell.....maybe boiler feed pump?
thanks
mike terry

Steamhead

That's probably a Vapor system

I would have loved to go to a school like that.

The typical Dunham system used radiator traps to vent the steam mains. These routed the air to the dry returns and out the main air eliminator.

If the air is not leaving the dry return, check the air eliminator. This unit has a vacuum check screwed into the top that may not be working, and a float inside that keeps water from leaving if the return gets flooded. You have two choices with this thing: You can fix it, or replace it with some standard main vents.

I like to use Gorton #2 vents on Vapor systems. Each #2 has 4 times the capacity of a Hoffman #75, and only costs as much as one #75. Gorton's site is www.gorton-valves.com .

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