steam heat

JSPAK

ok here it is .. i work in a maintenance system in a school system . 14 schools ....over the past 15 years we have had 2 new replacement steam boilers roughly 2,000,000 btu's(per boiler) put in each of 9 schools .... each school is just about the same design ....(school system used same blueprints building schools in the 50's and 60's ...every school i watched contractor install the boilers .... excellent installation ...piped properly and all ....here 's the 2 things that bothers me and i think might be cause of problem....contractor eliminated the vacuum pumps ... and installed boiler feed tanks ....runs are anywhere from 200 to 350 feet serving up to 9 classrooms on each run ....steam out ..... condensate line back .....schools are all one level ....also contractor never cleaned (skimmed) boilers when first installed .... when i questioned him he said his men wipe down the threaded pipes(eliminating oil ) and 90 % of pipes are welded anyway .....geeeez i installed boilers 20 years ago and after i was done installing that was taught to me that that was part of the job ....every year i get complaints that at end of runs radiators are banging when heat is starting to call..think a proper cleaning of whole system might help?

Steamhead (in transit)

If the original system design

used vacuum pumps, that contractor made a BIG mistake by ripping them out. Go back to the original design to be sure. That type of system used vacuum to pull air and condensate from the mains and returns. If the condensate can't leave the steam mains it will bang.

You may find that "lift fittings" were used to serve radiators located below the mains. In this case it's best to replace them with a transfer pump. Details on this are in chapter 12 of "The Lost Art of Steam Heating".

And yes- clean those boilers!

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Dave_4

Vacuum cleaning

Nothing like a vacuum pump to suck up all the dirty fouled up air messing up steam distribution, plus it takes care of any improper pitch in the long, very long 300 feet runs.

Return lines condensate puddles appear anywhere there is improper pitch or defective traps. Getting these two items out of the way will help enormously.

Also, your zoned radiators at the system extremities might be suffering from poor venting (due to the causes described above). Now that you no longer have a vacuum suck, you might have to add open breather holes in the return lines to insure atmospheric conditions within the return system.

With vacuum, you were always under subatmospheric conditions. Without pump, and under the best design, the two pipe returns are at atmospheric pressure. With any steam trap hiccup or any inappropriate plugging of an air hole with an air vent or even a plug, your two pipe return (with traps at the radiator) goes into apoplexy, thus the banging fit.

This type of water hammer can be quite damaging given appropriate pipe length for slugs of condensate to accelerate.

Is your school board into a sabotage mode where it wishes for the most destructive maintenance in order to justify tax hikes and new building construction? Cutting vacuum pumps does just that. Our local government run schools unashamedly indulge in these taxpayer blackmail tactics, it's really gross and the kids who haven't been pulled out are the ones who suffer - not to mention property owners and businesses.

Hopeless school boards could do with lots of vacuuming too.

Brad White

Never Say \"Vacuum\" to a Deaf Person

Ahem.

Steamhead is abundantly correct as is Christian.

There is another reason: If the system was designed to use a vacuum pump, chances are that the return condensate piping is sized a size or two smaller than it would be for gravity return. This was done to reduce the volume of vacuum to be maintained.

It is a system.