Steam vacum system

gerry gill

taller than the empire state building?

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MagWheel

Vacum Steam systems

I have a vacum steam system that is venting steam out of the vacum pump. I have changed the traps in the building and I still have excessive steam blowing out the vent. The boiler is set to run at 7#s. Is this pressure correct?

Bob W._3

7 oz. would be more like it. 1 lb. of pressure will send steam about 2/3 mile high.

Christian Egli_2

Save our vacuum pumps

Stop the vacuum pump when things get steamy hot, there is a big risk you'll destroy the impellers by cavitation.

Does your vacuumizer already have a thermostatic shut off for when the condensate gets hot?

MagWheel

How much vacum should be on this system? The building is 2 story and the pump is in the basement. What is the ideal pressure for this application? Thank you for your response.

Christian Egli_2

Do you need a lift?

Depends on your system. Do you have any vacuum lifts anywhere? That altitude will give you the constant minimum vacuum necessary. Think of getting rid of vacuum lifts, they are expensive to run.

Otherwise, look at your vacuum pump as a start up air exhauster assist. Have is go on as soon as the boiler fires, run it as hard as you can to suck all the air out as fast as possible. Then, within minutes, once the boiler is steaming and the steam has reached all areas, you can stop the pump. Running it on elapsed time or on an end of main hot temperature signal for each call for heat makes a lot of sense.

Vacuum pumps are rated to suck xxx CFM at xx inHg, it's just one point on a curve similar to the flow charts for circulators. It doesn't mean they don't operate anywhere else.

Check the vacuum relief valves. Hoffman puts one on the pump, and your piping might have one in the boiler room. These can be a source of leak (of air into the system), they are not particularly useful in my opinion and are just as well replaced by a plug.

You didn't pay good money to create a vacuum to have a relief valve just waste it.

The boiler has no need to develop any pressure at all, go with a vaporstat.

The start up air exhauster assist is very helpful indeed. It make the operation very efficient because it instantifies the time of steam delivery.