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

ethicalpaul

yeah that’s the myth. Everyone just repeats it because that’s what they read somewhere but nobody ever tested it.

Henry Gifford knew it was false and probably a few other people

STEAM DOCTOR

Just taking a guess over here. There are probably systems where there is not much of a pressure drop between the boiler and the end of the main. Well piped, smaller system, with nice clean water in the boiler... Probably not much of a pressure drop. But take a larger boiler, that might be running at higher pressure than it really should, with a very long main, that might be undersized, with wet Steam which contributes to pressure drops, and there might be a significant pressure difference between the boiler and the far end of the main. Which would certainly lead to water being pushed out of the boiler. To accommodate all systems and scenarios, the A dimension probably became the industry standard. Just a guess

ethicalpaul

Well it never hurt anyone, for sure. But I'd pay $100 to see any residential system that had more than 1" of water column between the boiler and the end of the main.

EBEBRATT-Ed

@109A_5

Bringing the return line into the boiler at the height of the Hartford loop connection won't work. If in the rare occurrence a return line leaked the water would syphon out of the boiler. You need the header drip to break the syphon.

techforlife

If memory serves me, I believe the Hartford insurance co. came up with the Loop and Equalizer (anti syphon) before there were any LWCOs. Maybe also because one cannot just turn off a coal fire. They found a way to keep most of the water in the boiler primarily for safety reasons.

109A_5

https://forum.heatinghelp.com/discussion/comment/1846148#Comment_1846148

Not my design, apparently a method they experimented with long ago. Although once the boiler water line dropped below the tapping height the siphon would stop (no dip tube inside the boiler). Likewise without the equalizer connected to or at the top of the Hartford loop horizontal pipe the wet return would siphon the boiler almost dry or at least to the level of the leak of the wet return (whichever lets the air in first to break the siphon).

Depending on how you read the article it seems to imply the equalizer is part of the Hartford loop assembly. Which it is needed to provide a vacuum break to stop the siphon.

With the Gifford loop the horizontal portion or connection is high enough that there won't be a siphon.

ChrisJ

Perhaps that's where the name equalizer comes from.

It equalizes the negative pressure when the pipe breaks so it "vents" the loop and stops it from siphoning from the boiler. It never had anything to do with equalizing positive pressure when the system is intact and never actually does anything to a properly functioning system.

I've brought that up a few times, but didn't think the name had anything to do with it until now.

ScottSecor

@ethicalpaul I am sure you have posted the details of your current steam system. I recall you have a Peerless 63 gas steam boiler. Just for reference, please share some details of your system (again) so I can get some perspective. Like others, I am thinking about and trying to visualize what is going on.

How many radiators do you have heating your house?

How many rooms are in your house?

What diameter and how long are your steam main(s)?

Do you have any other source of heat besides this steam boiler?

I believe your main(s) are well insulated, is this correct?

Are your steam mains in heated space?

I apologize for all of the questions in advance.

Thank you,

Scott

ethicalpaul

I have 7 radiators, 9 rooms depending on how you count, my single main is 2" for about 20' and then 1.5" for another 20'. It's my only source of heat used in the winter. My main is pretty completely insulated. My main is in unheated basement.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1846396#Comment_1846396

And when you finish the first page of that application @ethicalpaul, page 2 needs

Social Security number

current address

previous address for the last 25 years

names of all you children

Your mother's madden name

at least 5 of your most used passwords (especially your debit card PIN)

annual income

marital status

and your dog's name.

ethicalpaul

The best way to see what I am saying about the equalizer is to watch my 27 minute video. I'll have to watch it again to make sure I didn't say anything crazy but I think it's pretty good.

One interesting thing is when I started the video, I was still under the impression that there would be a noticeable pressure drop from the start of the main to the end. But residential steam is too slow and too small for it to be enough to let the water level rise at the far end of the main. You can see me figure this out during the video.

In the video below I have pressure gauges hooked up as well as a sight glass at the far end of the main to monitor the water line movement (there isn't any).

This is why I keep saying "Dimension A is a myth". Don't feel bad, even Peerless still thinks it's a "thing". Peerless says there's a 1/2 psi of pressure differential at the end of the main (hence why you need dimension A). But it's false, at least in residential low-pressure steam (to include multi-family buildings too).

Peerless also thinks there is another 6 inches due to friction loss through the return line, which is complete fallacy in my experience. And 8 inches for cold start-up condensate load, which is a load of BS because the condensate at all times is exactly the same. The boiler is making X steam per minute regardless of startup or otherwise. Ignore the drawing below, it's make-believe.

https://youtu.be/6ZLg3fqU1MQ

archibald tuttle

wow, how did i miss this thread. i agree with those who want the gauges. while i absolutely concede the gauges would read differently during start/steam up assuming the system reaches some kind of fully steamed balance (and presuming although we're using big numbers like 5 psi that is would be more like 1 or 2) my theory is that you don't need much flow to fill the steam main and it doesn't have anything like the pipe friction of the tangents to the radiators so I don't believe you would see much difference in pressure at the end of the steam main (maybe if it had inadequate venitng then all bets are off).

and how, in any operating scenario are you going to siphon through the hartford loop without such an "equalizer" because without a check valve, gravity keeps the wet return full and so there absent a leak in the wet return there is no lower outlet for boiler water to siphon too albeit a very small amount might back out as boiler pressure increases and has not yet reached the end of the main and I agree with ethical paul (not saying he's ethical, different debate) that the "equalizer" will not change that because it isn't a siphon. it is just pressure going back through the wet return taking the column a little higher.

now I have to contemplate if the gifford with equalizer approach would give you a slightly different result in the startup imbalance time as there you would be better preventing boiler water from rising to the weir of the gifford loop. how important that is I don't really know but i hope to get some knowledge but not to get schooled ;- )

nonetheless, I was always taught, edumacated, guessed, that you use vapor control so in worst case scenario if you have boiler pressure backing (metaphorically and a little bit literally) into the return, and you have literally no steam pressure at the end of the main, there is enough A/B separation from the 'dry' return that you will still put water back in the boiler and won't fill the dry return. And if you don't have that kind of separation and don't want to depend on big well vented mains you use a condensate return pump . . .

that makes the "equalizer" into a "surging feed return separator" or some such made most especially effective with near boiler drop header piping.

OK all you Rip Van Winkles, i let you get a couple of years of sleep before I stirred this up ;- )

Jamie Hall

Where's my wooden stake?

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1874980#Comment_1874980

With the price of beef lately I'm not surprised.....

archibald tuttle

@ChrisJ

a beef is cheap here . . . .

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1875051#Comment_1875051

ratio

@HeatingHelp.com, I ask again: can we get a "Groan" button? 😁

ethicalpaul

I will just say @archibald tuttle that I did run several tests with accurate gauges at the boiler and at the far end of the main and I never saw any measurable difference in pressure between them at any point in the heating cycle.

If we think about it, it makes sense. Pressure differential "travels" or equalizes at something like the speed of sound (which is in fact what sound is). There just isn't enough friction in a home system at home pressures to ever see any kind of pressure drop.

ChrisJ

I can't help but think of this every time one of these discussions comes up.

archibald tuttle

@ethicalpaul

glad to hear that you did some gauging because I always like to try to match the theoretical to the real world.

so one thing that maybe i gotta do now is go back to deadmen basics. if the pressure is essentially the same at the end of the steam main as in the boiler chamber why do you need an A/B difference equal to the steam pressure to put water back in the boiler?

i did not gauge the pressure in the main but this is my very emperical experiment complete with polycarbonate section in the vertical drop to wet return to test the theory. this was one pipe pitched away from the boiler and around the basement and back to the condensate return so parallel not counterflow in the main.

https://www.youtube.com/watch?v=GCv7iKi0xgg

so if you watch the entire scintillating broadcast you'll see that thge boiler is putting out about 7.25 inches WC of steam pressure, the weir of the gifford loop is about 40 and 3/4" off the floor and the condensate level in the wet return is about 45 and 3/4" (used a level to make sure the floor was level between those points). now that is close to the reading of steam pressure but maybe it just coincidentally represents the pipe friction in the wet return and just enough of a balance of water to cause it to rise over the weir of the gifford loop and return to the boiler. but that is an A/B of 4"!

this was up and steaming and I expect if I had put a tee with a gauge at the end of the main where i hooked up the polycarbonate return I would have gotten pretty similar pressure, but that would have been a smart addition to my experiment. sold that house so I can't go back and try that again. but i had a great transparent setup for illustrating A/B though.

in this case the normative 28" A/B is excess and you could get away with a lot closer. maybe if you had more volume of condensate and did not have a larger wet return apparent pipe friction would increase a little. here is the AI version of where you get the 28" which I realize i falsely remembered was on the assumption of a 1 lb. difference in pressure (and indeed your reading of pressure at the end of the main and my reading of height of water in a wet return suggest that really it is mostly a little friction and need for a slight gravity advantage to build up with condensate in order to put it away–and notice this being gifford loop that the condensate actually had to be raised several inches over the boiler water level!) so the more I think about if returning in a hartford loop the measurements might have been even a little closer.)

AI take on A/B difference:

• Pressure differential: About 14 inches (½ psig) to equalize the pressure difference between the boiler and the end of the steam main.

• Friction loss: Another 6 inches for the friction loss through the return line.

• Start-up load: An additional 8 inches to handle the cold start-up condensate load. 

( I doubt the 1/2 pressure differential)

ethicalpaul

OK well first you can't trust AI because it only takes from stuff it read from all sources on the internet.

why do you need an A/B difference equal to the steam pressure to put water back in the boiler?

You don't. The "A" dimension is complete myth. (To clarify, I believe the "A" dimension pertains to 1-pipe systems.)

Peerless themselves publish a diagram showing the A dimension and all the things that go into it, which I find to be completely mythological because I have seen that the waterline at the far end of the main never budges, regardless of pressure. This makes sense because the same pressure is delivered via the wet return and the main, and so nothing is going to move waterline-wise.

I did watch your video (I had watched it in the past as well—I love your polycarbonate drip) and I wonder if you ever measured it when the boiler wasn't running to see if it moved. In my experience, it won't. I also can't quite tell what is going on with the different piping in your system. If there are any openings to atmosphere or restrictions to steam flow (like a partially closed valve—I'm not talking about pipe resistance) that can definitely move it.

Here's my post from earlier in this thread that shows the peerless diagram and my video disputing what it shows:

https://forum.heatinghelp.com/discussion/comment/1846404#Comment_1846404

HydronicMike

This thread has been going on over 2.5 years. I find it very interesting and though provoking. I am a little curious about the fact the founder of the website never weighed in. No thoughts at all?

archibald tuttle

@HydronicMike

guess i'm going for 3 years. why quit when you're behind ;- ). I wouldn't be thinking of this stuff if not for Dan, i'd just be putting back more or less what was there before which, in its own way, is reliance on the deadmen. If he has something to say i'm sure he won't be bashful but a nice compliment of dangeous livemen to debate this stuff here.

so tying in with this gifford loop thread and in the patent linked there, mr. gifford seems to have left out an illustration of the prior art that I have encountered numerous times which is no deep trap wet return to begin with but just a single downturn at the end of a parallel flow either into the drip leg or as a second drip leg from the main which is also the parallel flow dry return. and that downturn would obviously be a bit lower than where the steam enters the main and drops directly to a low tapping on the boiler but exposes really no more wet piping with risk of breech to that low tapping than the normal loop approach.

I have to stop and think to myself if such a circumstance really calls for a loop style connection at all and it still goes back to how do you reliably put condensate back in the boiler and does the method for doing so create any instability in operation/water level. do you need the weight of a long loop trapped wet return to act in a way as a metaphorical check valve or directional signal for the condensate return process? or is just the pitch of the pipe bringing gravity return in either counter or parallel flow taking care of that. Indeed, on the rad takeoffs from main in single pipe this is how it works and we just upsize for the counterflow. I have used gifford approach on occasion–don't know if I was supposed to join his substack or somesuch in respect for the patent although it is expired now, I think. But I would show appreciation for anyone who has made contribution. So the question of contribution is not: does it work?; but does it work better? This approach actually provides less weight of water to prevent steam hammering up the return so i'm unconvinced whether it really has a stablizing impact although it works fine, does it work better?

But this gets me to the point of wondering do you need trapped water return at all for stable water level? I propose the heretical thought experiment of connecting the return without a loop higher into the boiler–even at gifford height, i.e. side outlet to steam chest or just below cutoff waterline. I tend to think you would want it all the way above or below the waterline just because of the chaos at the surface, but does it need to be to the bottom of the water jacket the way we most commonly do it? Don't know if there is some reason to believe that long condensate wet return/trap is needed for stability but more likely to leak than the short run of a dry return dropping right to the bottom of the boiler thus supporting the hartford loop configuration . the close boiler piping could also leak so if you connect to boiler itself near or above the waterline rather than the drip leg, that is hartford or gifford plus, is it not? Why is industry standard the drip leg other than convenience or lack of a suitably sized boiler tapping at heights that envisions this approach?

Here is my hook to this thread. By definition, regardless of any minor pressure drop to the end of the main which doesn't really seem to show up (see @ethicalpaul video) the equalizer equalizes its own pressure. so my assumption had always been that having standing water in the return (somewhat irrelevant of whether that is a longer wet return or literally just a stand pipe connecting to a higher dry return prevents steaming, slugging, bubbling up into the drip leg and the leg being isolated from the boiler fire and shortly receiveing condensate would stay slight cooler and not steam as readily. And then add to that the thermodynamic principle that the water lower in the boiler where connected would be cooler-not by alot and in the case of steam vs hydronic the difference might be as much a matter of kinetics as measurable temperature. so the lower tapping would exhibit less vapor pressure (not less total pressure, in theory it would be slightly more because of the weight of a foot and a half or so of water). So together the relatively small crosssection of the return compared to the water surface area in the steam chest and cooler water at lower connection, and that the piping pitches the condensate to the return means that an A/B differential (I might have that wrong, maybe it is just the A distance, I would fail multiple choice on that) provides a rise in a vertical portion of the wet return allowing the level in the return to build a bit higher than the boiler water level to use gravity to force condensate back into the boiler.

In real life I have never noted this to be anywhere near the 28 inch standard (and i realize where I internalized the wrong derivation of that standard (not that the announced derivation is anymore sensible as @ethicalpaul makes clear) . I was considering the possibility or running a two pipe system without a condensate return pump and thinking that if all the steam traps work–so with no steam pressure in the return–and i'm running at 1 lbs cutout, I would need 28" to overcome the 1 lbs and then a few more inches just to give gravity the real edge. But with the pressures more or less equal in a one pipe system that would not be the case.

Also a phenomenon that @ethicalpaul adverted to in his video that I maybe doubt is the notion that the pressure in the main would slightly reduce at each rad take off. I don't think that follows. instead the pressure would remain the same but the flow would be lessened. as a practical matter in the systems art of taking paths of least resistance we know that there are rads–often but not always at the end of the system–that fill last; but my instinct is that doesn't revel a lack of pressure but a lack of steam.

It seems the deadmen thought that the cooler? or deader? water at the bottom of the boiler would be a more stable return path. I don't know if that was an emperical or theoretical development. it follows from passive hyrdronic technology but it doesn't really present itself as an absolute for steam. Does the low connection provide more resistance to steam forcing its way backwards and, if it does, does that make it necessary or simply an alternative. My inquiring mind wonders if the drip leg is sized accordingly, is there some reason that the condensate can't just essentially counterflow into the boiler if the return were connected above the waterline because it has the power of gravity and the pressure is equal by definition so you are just counting on water being heavier than steam?

Were the return small i would imagine you could get momentary occlusion with high return rate that might lead to hammer if it created differences in what i will describe as kinetic steam potential independent of pressure since the pressures would be virtually equal on both sides of such occlusion thanks to what could then properly be described as an equalizer. I don't know how big the difference would need to be to cause hammer or fluctuation of some sort but I would think that sizing the vertical drip leg larger would pretty much eliminate that. In broad metaphor this would be like what is considered the wrong approach with double risers, i.e. connecting them with the takeoff tee in between rather than creating a parallel flow toward a drip leg with a takeoff after the combination. So maybe this connection below the water line is simply meant not to create chaos with regard to steam flow direction and brings stable operation in that manner and is less about whether the return could function without such trapped water leg.

sorry about that novel.

brian