The "equalizer" is mis-named. It does nothing to equalize anything.

WOW... This went to 2 pages while I was away for the day!

But to put this in perspective. @ethicalpaul has not the experience of many herein. His knowledge comes from his interaction with us on the forum and reading what is available in other media such as books and webinars and the like… and doing his own heating system. Not from working on other peoples equipment. And seeing what Paul has accomplished with his small residential system, has helped many a novice Professional learn about different types of pressures and chemicals that one might use in a boiler system. With his glass pipes we can see wet steam and dry steam happen at different occasions and tests that he has performed and was kind enough to video record and share with us.

AMAZING STUFF PAUL... THANKS

And as I stated more than once, based on what Paul has in his basement, he is correct about not actually needing some of what we have come to know as professionals, to be Standard Operating Procedure. But many of us are looking at the reason for these features like the Hartford loop and equalizer and Dimension "A" based on what we do today. But this has evolved from the Dead Men that started this science of Boilers. Every Tom, ****, (automatic censored for obvious reason but that was not my intention LOL) and Harry in the late 1700s and early 1800s were trying their hand at "The Better Way" of providing heat for the home. Benjamin Franklin came up with a better kitchen stove that used less fuel than the old fireplace with a swing arm that held a pot of food or stew over the flame. Heat the home and cook the meal using less fuel.

Some of those inventions were heating radiators with 100 PSI Steam. Think about that when you consider an equalizer on a header. And as far as the pressure readings on the diagrams. @STEVEusaPA They are not actual readings from any test that I have completed. They are from memory of my Oil Burner classes that Mr Spence used on the black board at Philadelphia Wireless Technical Institute on Pine Street in Philadelphia in 1974. That is why I suggested that Paul add some gauges and the valve on the equalizer to simulate the “No Equalizer” condition for a test. I don't have a steam boiler in my home to conduct that test or I might be inclined to place 4 or 5 pressure gauge ports to see how the pressure drop actually happens over the length of the main. (Although I don't believe that Paul has a long enough main to have a significant pressure drop to confirm my guesstimate numbers.)

Back to the 18th, 19th, and early 20th century… When those weird piping designs like the Hartford and Gifford Loop were introduced. There were real boiler explosions happening on a regular basis. And every new “SAFER” design would be incorporated into the next “SAFER” design until we get to the year 2023 where this is now a Lost Art. (sounds like the beginning of a book title). Since we have the benefit of the dead men, we continue to implement the EQUALIZER that may have first been used on some boiler that was operating at 50 PSI by the inventor’s design, only to need to add that pipe (that is unnecessary on a system that operates on less than 2 PSI) in order to stop the system from pushing out the boiler water into the return where the check valve has failed. And VIOLA! It happens to be a great way to put wet steam back into the return so it is not forced into the main. And counterflow mains don't dump condensate into the boiler supply pipe. And since someone already called it an EQUALIZER, why should we change the name.

And I never said that the equalizer made the pressure EQUAL at the end of the main… only at the boiler. If i'm not mistaken, I believe that Paul might want the equalizer to be making the pressure equal throughout the entire main, or why do we need it, or even call it by that name. I surmise this by the original query. But I might be mistaken. The EQUALIZER makes the steam pressure Equal at both ports. Regardless of the weight of the water.

This has been a reading from the heating bible according to Mr. Ed

ALL: Amen

ED: Let us pray...

hot_rod said:

This whole post reminds me of a book called Pumping Away, how that author had the audacity to take on an entire industry of all knowing boiler engineers about expansion tank placement.
How dare he!
Wait until the book banners in Florida get a of that wokeness
woke: a state of being aware

It's amazing the guys I see posting on this saying "We don't have time for this" yet they have ample time to attack it and say it's silly.

Somehow I'm caught up in this . I just did a little experiment with some vinyl tube to replicate a hartford loop. Once the boiler water level falls below the weir of the hartford loop tee, any additional pressure differential causes the water already in the wet return to be pushed out. So the equalizer ensures that once the boiler level has fallen to that critical point, system pressures, regardless of what they are, have no effect on boiler water level. Gravity keeps the water in place because the pressures are equalized. It is certainly a vital part of the hartford loop, regardless of how we feel about the usefulness of it. And to me, even if the hartford loop only gives our low water cutoff an additional 15 or 20 minutes to dry off and disable the burner it is worth it.