Best Of

I don't know but someone should be shot for jamming the boiler in there with the controls up against the wall. Makes it difficult to maintain.

Just replace 2-3 sections if they are bad and re- gasket where it is leaking and move on. Make sure the controls work and fix any leaks and fix the venting.

Then in 2-3 years you may have more leaks

On a 1 pipe system, the equalizer does not affect the operation of the system relating to pressure. There is no actual "equalization" function it performs.

It makes an excellent drain from the header for any condensate or carryover that makes it to the header. But if carryover occurs, it's going to go all the way to the mains, and that's not great. Water can get pushed all the way to your radiator vents and your main vent.

A boiler can run just fine without it, but there's no reason not to have one. It helps.

Diagram A

Assuming there is small p pressure on the very left side, an application that this would involve would be an air handler that has negative pressure, there would need to be a vent on the lower pipe so that water could push its way out. The water column, about 3in, combined with that small pressure gives us enough pressure to push its way out. If the air vent were not there, the water could not push its way out effectively because there is a lower pressure on the very left side and higher pressure on the right side. The air vent essentially disables the lower pressure by introducing atmospheric pressure thus equalizing at the air vent and the right side outlet. Take a straw, fill with water, play with the water level because it’s fun to see how it works, put finger over top hole and tilt the straw enough so water drains out. You will see it drain slow, but it drains because there is still some pressure sneaking in. Now do the same thing but without putting your finger over the top hole. You will see the water fall out really quick. 

Diagram B

I want to start by saying most residential systems I work on do not have a big enough B dimension to achieve what I think you, Paul, are trying to get at with saying the equalizer does nothing. I do think that if there was a high enough B dimension and a properly placed air vent above the B dimension, that hopefully never sees steam and causes a horrible siphon, that one could achieve a two pipe system without an equalizer. This of course would mean everything is working properly and set up correctly to do so. But even if you did get it working, I think the water would drain really slow if at all (please correct me if I am wrong in thinking this). Water falling creates a vacuum, which is why the air vent would break that vacuum, but you would need a big vent and one that is functioning. Relying on a vent is scary as they can fail. I can easily rely on an equalizer as I don’t have to worry it would stop working on me. This is what the equalizer does, it breaks the vacuum. This is what the vent does on a p trap, it breaks the vacuum. If you’ve ever worked on a p trap, like the one I described above, you could plug the vent and watch the trap not work anymore. You need vents on your house plumbing or things wouldn’t work correctly and your house would smell like crap. Fun fact, the guy who improved the p trap design is named Thomas Crapper. Just like you Paul, I would love to see a test of a two pipe system without an equalizer to end this debate. From my experience, I don’t think it will work the way you want it to. I’ll do what people smarter than me do, install equalizers because they work. 

Whats the rating on the f&t traps in terms of capacity? also, whats the rated pressure difference on the F&T traps. Maybe they needed to go to a zero back pressure condensate return tank inorder to operate properly. If you do pull out the F&T traps and make a wet gravity return you will have to pipe in, PROPERLY, airvents in lue of the F&T traps coming off the top of the mains 12 inches back from the ends of the mains. I would replace all traps if aged out and the young ones I would test all the F&t traps for proper flow and operation. I would fix or replace the condensate tank and when replacing the boiler include in the bid for high pressure flushing of all the piping you can get to so that crude isnt going to cause you warranty issues. Then get it in writting to have you do regular maintenance, water quality, ph, and skimming or the warranty is voided