They said the boilers leaking, we need it replaced.

Double D

This call started off with a leaking boiler. So far the only good thing was the boiler is a close match for the installed radiation.
When I looked the system over I noticed all of the F&Ts have the discharge side piped upward to the dry return. Some have vacuum breakers. The dry return ends at a door loop outside the boiler room which leads to the inlet of a vacuum pump.
A small section of main which heats offices was connected to a small residential size boiler. The boiler is closely matched for the connecting load and the boiler is properly piped. The ends of mains for this small boiler also have the discharge side of the F&Ts rise upward to the dry return however this boiler does not have a vacuum pump.
The end of the dry return turns down to meet a wet return leading to the boiler.
Before the turn down there is a T with a Hoffman 4A. 

I don't come across a lot of vacuum systems but systems I have come across over the years were not piped this way.

Mad Dog_2

Hows the Header?   Mad Dog

Double D

@Mad Dog_2 No header to speak of. Welded boiler risers injecting the old header.

109A_5

Double D said:

I don't come across a lot of vacuum systems but systems I have come across over the years were not piped this way.

To me it looks like they use one pump to utilize many 'vacuum lift stations' to return the condensate to the boiler(s). I think this strategy was used to maintain usable space in the basement rooms (to maintain safe headroom) without the pipes being in the way of the occupants or underground. Probably would have cost a lot more to dig a deeper basement and all the pipes are where you can service them.

JohnNY

They don't seem to have my pants size.

I come across systems like this frequently. This is the difference between residential and commercial steam heating. The common knowledge of keeping the operating pressure super low goes right out the window. Oftentimes we have to lift condensate and the way to do that is by running the system at 3-5 PSI or more. At the General Society building, which some of you have seen, the point of entry for the steam into the building forces us to push condensate up about three feet just to get rid of it.

I like jobs like this where you can make a real difference.

The Steam Whisperer

It looks like that photo of two traps above the clothes rack have lift fittings at the outlet. The smaller 3/4 inch pipe is threaded down into the larger drip pipe to act as a straw to lift the water to the return line. No additional pressure is needed to make these work... just a properly funcition vacuum pump running at the typical 5 inches mercury vacuum ( enough for a couple feet of lift). However, it looks like a lot of the traps have been replaced and the correct lift fittings were not installed. I find they often will work anyway, probably just not as well.

JohnNY

The Steam Whisperer said:

It looks like that photo of two traps above the clothes rack have lift fittings at the outlet.

I don't see any lift fittings in the photos. Just cleanout/drip tees. Truth be told, I can't recall seeing a proper lift fitting in the wild in decades. Aren'y they sort of T-Y shaped and have a limit of like 3 feet vertical or something?

JohnNY

@The Steam Whisperer
Actually, you're right. I've never made one. I'd like to see this work.

The Steam Whisperer

I'm not sure if I've ever seen one in the wild either. They always just connected whatever it is to go up and over into the return.... not suction straw.

109A_5

Maybe another

https://forum.heatinghelp.com/discussion/185167/webster-steam-system-with-vacuum-pumps/p2

Double D

I never gave any updates on how that one is doing. Fuel usage dropped considerably. Gas company had to lower the pressure on their regulators 3 times to stop their alarms from going off. Numerous failed traps in the building. Several piping corrections.
Lots of great advice from the wall. @Pumpguy was a tremendous help. I still need to get back to do some corrections on the smaller vacuum pump he suggested. They are happy with the way it's performing now. Even heating and no hammering.