Equalizer Return

It carries water, not steam so it can be smaller. Pipe diameter doesn't figure into delivering pressure to the return.

@ethicalpaul

In a properly operating boiler, there is no liquid water in the header. The very small amount of condensation that might be there gets re-evaporated by the steam rushing by. I have watched it.

If the boiler is surging, then yes, the equalizer can return some of that water back to the boiler, but a lot of water can still go up to the mains regardless of the equalizer being there (because the steam carries it to the main).

So yes, the equalizer can be very small indeed because it really doesn't do much.

Sorry for saying so, but that old thread has a lot of incorrect information in it. But like Steam Doctor said, you've heard this from me already.

But you guys know there's no water in the header, right? (Unless something is very wrong)

@ethicalpaulIdeally there wouldn't be water in the header. Realistically, not so sure that's the case. Not everyone has a boiler that is sparkly clean. And I would assume that even the cleanest boiler can be thrown out of wack, if some sludge from the returns finds it's way back to the boiler water. Overfired boiler can be trouble as well.

tiny droplets that hug the pipe walls and mostly get turned back into steam. I didn’t put sight glasses on my risers to never look at them.

@ChrisJ

Just my opinion.

When the boiler is not firing there will be more pressure at the bottom of the boiler than above the water line. Atmospheric pressure will be pushing down on the water and the top of the boiler is vented to the atmosphere.

As the boiler builds pressure the pressure on the water at the water level pushes down on the water which will tend to force water out the return. Since the same pressure is pushing down on the water from the header through the equalizer the water level is equalized and the water level in the equalizer should roughly match the sight glass. Without the equalizer water could be pushed into the return.

This may change depending on the system. In a one pipe system with the end of the steam main connected to the return the equalizer may not be needed as @ethicalpaul has shown. In a two-pipe system with no pressure in the returns due to steam traps that could be a different issue as could a large one pipe system in an apartment building with 100s of feet of pipe the pressure at the far end of the steam main may not equalize as well as it would at the boiler.

Weather you need an equalizer to drain the header is another issue. Properly piped boilers with low velocity in the boiler risers may not require an equalizer for a header drain.

This site abounds with picture on various posts of boiler with crappy piping that work fine without an equalizer or an improperly piped equalizer.

But if you install a boiler how do you know if it will work or not?

Most would install the equalizer because the MFG recommends it even if it is not "needed". It would cost a lot more to go back and install it if the job does not work than the cost of a few fittings and some pipe and some labor.

The equalizer "equalizes" the pressure between the header and the bottom of the boiler which is already skewed a little by the weight of the water

You guys are driving me crazy. I've been thinking through this whole thing — and the only conclusion which makes any sense to me is… it depends. That's so helpful. But… I think it may be right.

Consider first the boiler off. Under those conditions, the water level in the wet return —assuming the Hartford Loop is right (we'll keep up that assumption!) will be exactly the same as the water level in the boiler. So will the water level in the distant ends of the returns and the drips. Fine. No need for the equalizer, at least for pressure.

Now fire up the boiler and run it at a very low pressure — typical residential perhaps. With a nice generous header. The pressure drop from the boiler into the header and, by extension, the equalizer will be negligible. Again, who needs it? Well, as pointed out it does served to take return water from the header, which, depending on design, may or may not be significant.

But now let's consider a boiler running at a higher pressure, and perhaps with a header and riser system which does have a significant pressure drop. Now the equalizer — sensing basically header and mains initial pressure — will be lower than the boiler, and the equalizer will make sure that the pressure in the returns is the same as that at the start of the mains, not that of the boiler. This will help ensure that the water does not rise too much in the various drips and the wet return. Without the equalizer, the returns — and hence the drops — would see the higher boiler pressure, and the condensate would rise farther.

Or am I way off base…

Was the Hartford loop originally installed on home heating boilers?

I agree with you. The best reason I have heard is to prevent the water from syphoning out of the boiler if the wet return gets a leak (with a Hartford Loop installed).

Then I think someone got the mistaken idea that it would prevent water from being pushed out the back of the boiler, but this is clearly false (because even without it, the water stays in the boiler).

There is a Weil-McLain diagram from 1987 that gives both reasons, see below.

Hmm, I think I see what they were trying to say in this diagram. The way the diagram is drawn, it would prevent water from being pushed out of the boiler, but the drawing is incomplete. It is not showing the main. With the main in place, the pressure pushes across the main and down to the far water line the same as the pressure pushes against the near water line. The diagram is incorrect that the pressure is different at A and B (when the main is in place).

I think someone looked at this and thought it was doing more than it was actually doing.

If the main wasn't there (and the riser was capped), the water line at B would indeed rise (and in my EQ video I showed this by closing the valve on my riser), but in a real system it does not, even in incorrectly-piped systems with no equalizer or hartford loop.

I think this incorrect notion has carried on because it never hurt anyone, and because no one ever measured the pressure at B, nor installed a sight glass at the wet return drip's water line before.

I really cannot believe this is even a thread ! I find it a absolute waste of typing and discussing just to discuss some thing that every person who install steam boiler for a living do not waste there time re thinking in belief that it unnecessary . You may do what ever u want on your own boiler in and for any belief that you discover is the key to some sort of unknown knowledge . But the truth be told I know of no professional licensed plumber or hvac contractor who would install a boiler without a equilizer unless they had zero experiences . I ve seen job where installer tryed to reuse a header w a terrible equilizer and ran into issue mostly due to the fact older boiler always produced dry steam unless the boiler is full of oils ,mud or a above normal water line . I find it a complete comedy that you guys discuss a subject to which there’s nothing to discuss it’s been done this way and is included in every installation manual for the last 40 years but I guesss you guys are smarter then those who can up with all this stuff .i,m sure they had a reason for it and as much as some of you argue it .I say go out and install a couple boilers and have some one pay you where you are responsible for it proper operation including water not backing out of the boiler and it working correctly . Just because you have installed you own boiler and it works kudos to you . But how about you go out install a couple of dozen of boilers for customers and get them inspected and turn a profit and not return for installation issues and be held liable for poor operation and also turn a profit so you can eat . It very easy to discuss subject to which there a bunch of hypothetical ways to skin a cat but unless you want to work for free you follow instruction and not make up non sense which clearly is not known as standard and proper except for those who have tons of time and believe there brains are larger then those who have been manufacturing and have included I and o instructions ,They been manufacturing boilers long before you and I have been around but as stated stop beating a dead horse on a subject that clearly does not need to be discussed . It under minds those of us who try to make a living and when having to explain this to customer who has been feed mis information from non licensed experts who do not make a living and put food on the table not just stir a pot online . Go do it for a living and preach your sermon let’s see how much food you put on your table . O f yeah doing it for free w zero liability does not count being there are no monetary gains or looses to occur .
I really hope non of this offends anyone but just because you have a steam system in your home and installed it yourself that’s great but this does not make one a expert . Try to do this for over 40 some on years installing dozens of system a year without any issue then possibly you will stop beating a subject that has no merit .
peace and good luck clammy

Ps I know that some of you will continue to discuss and stir non issues . Kudos to you

My dear friend @clammy !

No one is advocating to not install an equalizer. But like Steam Doctor said, I think it's important to understand what it does and what it doesn't do. Isn't that the nature of Dan's books, the classes at the Mechanic's Institute, and this forum itself?

I'm still so appreciative of you for your guidance over the years that you have given me and so many others on this forum.

If you'd ever like to see my setup, I'm just down a ways from you in Cedar Grove. I'll be able to show you that the water level never moves at the far end of the main, regardless of pressure or equalizer, using my Peerless boiler that you yourself suggested I buy from Henry's (and I followed your advice). This offer is open to anyone on this forum, and is more than hypothetical 🙂

Unless someone forgets and leaves a king valve shut.

For better or worse, I'm one of those folks who not only want to know what we usually do — or what we may be required to do — but why. When I was younger I drove folks nuts that way — parents and teachers! — and I still do it, many decades on. Sorry…

First of all

Not all systems are 1 pipe, what about a 2 pipe system with no pressure in the returns after the traps will the water not be pushed into the empty returns?

Large systems with pressure drop will make the pressure at the far end of the main different than at the boiler.

And do you want to be the guy that didn't install the equalizer, voided the boiler warranty or has to go back and install one now that the job is finished. The few feet of pipe and the fittings save will be peanuts compared to what it will cost you to go back rework the header and the returns.

The old jobs installed before the Hartford loop became common always had a check valve in the return line connection to the boiler.

The old timers didn't like to waste money they didn't put a check valve in for no reason.

Ah… @ethicalpaul , on a two pipe system the pressure in the returns — whatever one wants to call them — should always be zero psig, except in some vacuum assisted systems where it will be a slight vacuum. Drips from the steam mains to the wet returns, if any, will be at steam pressure, of course, which means the water will stand lower in them than in the drips from the dry returns which are at zero (this, by the way, can get people in trouble if the steam pressure is too great or someone lowered the boiler water level, but we've been through that before).

Yes, in the drips connected to the main. The drips connected to the returns will stand enough higher to compensate for the pressure difference. Just a different way of saying the same thing…