Steam pressure and traps

It probably was a vapour system, once upon a time. More to the point, it probably ran beautifully.

Sigh.

Step one is going to be to research the Webster system and find out how it was supposed to work.

Step two — or step one in your working hours! — is going to be to find out how steam is getting into your dry returns. It doesn't belong there, and until you get rid of that problem it will never work. I suspect that your bad steam traps are the culprit there — fortunately, although it's a bore, they are usually pretty easy to repair.

Third is going to be to get the pressure under control. In fact, once you get rid of the steam in the returns the excess pressure is going to make the losing water problem worse. It is very likely that the system was intended to operate with a pressure differential between the mains and the dry returns of not more than 0.5 psi, and possibly less. Higher pressure differentials will indeed force water out of the boiler and into the dry returns.

The big Hoffman main vents wandering around the system may have been added in an effort to "fix" some other problem. Most vapour systems had one, and only one, main vent location at or very near the boiler, where the dry returns joined before dropping to the wet return to the Hartford Loop. They won't actually hurt anything —if they are working. They will if they aren't, and may not be needed at all.

Do I see an F&T trap? It is probably not needed — and, again, may have been an effort to "fix" a problem; in this case caused by excess pressure differential.

@joshua2002 , if you don't have it already, get a copy of @DanHolohan 's book "The Lost Art of Steam Heating", either the original or the Revisited version. The Webster Modulation System is in chapter 15.

This system was designed to work on 8 ounces or less pressure. This barely moves the needle on a standard 0-30# gauge.

That air trap is the only air vent in the system. The vent that's on it looks way too small. You need at least one Gorton #2 vent there. If the air can't get out, the steam can't get in.

You will probably find radiator traps piped between the ends of the steam mains and the dry returns. These are called "crossover traps" and they let the air out of the mains so steam can distribute quickly. I like to upgrade these to Barnes & Jones Big Mouth crossover traps to speed this process up and save fuel.

Do you know how they sized the boiler? The proper procedure is to count up all the radiation and choose a boiler that will handle that amount.

If the boiler is bigger, in terms of how many BTUh it can put out, than the radiation can absorb, it will build pressure. Which you don't want. The only solution to that — short of a new properly sized boiler —is to turn off the boiler when the pressure differential between the mains and the retruns exceeds 8 OUNCES. Then turn it back on when the differential drops again.

Pay close attention to @Steamhead 's comments. He really knows these systems.