OK What is it

Mike20

I have see these devices before but never on a job that I was responsible for.

It is on a 2 pipe steam heating system in a 30 unit apartment building. It is located on the return piping but there is a connection to the supply steam as well. There is a gauge glass on the main "tank"



At the top of all the piping there is a Large air vent

Though the system is two pipe there is no steam Condensate return pump/tank connected to the return line



HERE is my Guess

It is some sort of condensate return tank that makes use of steam to create vacuum in the return lines. My guess is the air vent is not supposed to be there

Any Way PLEASE HELP

Thank you

Mike

Steamhead

It's a Return Trap

basically a pressure-powered pump that can force the water back into the boiler if the pressure gets high enough that the water can't return by gravity. The sight glass is used for seeing the water level rise into the Return Trap, and drop when the trap is activated.  See chapter 15 of "The Lost Art of Steam Heating". 



The air vent appears to be mounted on a pipe coming out of a smaller cast-iron device. This is an "air trap" or "float trap/air eliminator". It is the one place in the system where air can be vented (larger systems used several of these). The vent appears to be a Hoffman #75 or #76, and is almost certainly too small for this application. You will likely need one or more Gorton #2 vents there.



At the ends of the steam mains, you will probably find traps connecting the steam mains with the dry returns. These are usually thermostatic radiator-type traps, but can be F&T traps too. Their job is to serve as main vents, letting the air out of the mains quickly so the steam can fill them.



Have you found names on any of these devices? This will help us ID the system. Also, take some more pics of the system and post them here.

gerry gill

Cool find.

Yes, like Steamhead says look for a name on the boiler return trap. That would most likely identify the system and it may very well have been patented which means its operating documentation is available..there is undoughtedly major room for efficiency upgrades to that system..But leave the return trap and float vent in place..They dont hurt and always identify the maker..I think venting would be a great opportunity there!

Mike20

The next question

I read chapter 15 in the Holy Book of steam and thanks to your answers I have a much better understanding of what I am looking at

My first inclination would be to take this out and replace it with a Steam condensate return Boiler feed pump (Following the precautions in Chapter 15)

However if is working There is no reason to do that

The thing is - How can I tell if it is working ?

I have an Infrared camera that I can use to test it , if that will help - What should I be looking for ?



It would seem to me that it is not working because someone installed an air vent on the air discharge line - This is usually a sure sign that the steam traps are not working. I have not Run the system yet since I was only there on a survey

I expect to return next week if for no other reason than to test this puppy out .



Thank you for all of your assistance

Mike G

Steamhead

Even if the Return Trap is shot

you do NOT need to install a return pump.



Remember, this was installed during the Coal Era, when it was more difficult to control the boiler pressure than it is now. Today we have a simple device called a Vaporstat, which can stop the burner at ounce pressures. As long as the pressure is kept low enough that the condensate can return by gravity, you don't need to pump it. And a return tank and pump, plus the additional traps that would be needed, will create more service headaches down the road. I repeat- you don't need a return tank and pump.



Listen to the Dead Men. They were geniuses.



The procedure for checking the Return Trap is outlined in chapter 15 of Lost Art. Basically, if steam goes into the Return Trap as soon as the boiler starts steaming, the internal valves are leaking. But if needed, I believe Tunstall can rebuild a Return Trap- call them and ask for Woody Tunstall, and tell him we sent you.



The air vent is another matter, though it is related. Vapor systems like this were designed to run at less than 1 PSI. But if the air can't get out at that pressure, the boiler will run and run, building more pressure than is needed to distribute the steam against the friction loss of the pipe. If that Hoffman is the only air vent on the system, it's way too small for a system of that size. A vent that is too small will slow the steam distribution and waste fuel.



Where is this system located?

Mike20

Location

The Project is located in Newark New Jersey

It would seem to me that no air vent valve would be needed. If the system were working as designed wouldn't there just be an open pipe to the atmosphere - Much like the vent on a condensate return pump?

Thank you again for your assistance and the benefit of your experience.

Mike G

Steamhead

The Float Trap/Air Eliminator

IS the air vent. It is an open pipe, with a float to close the opening if water backs up that far.



However, it may be stuck, or may simply not be big enough to vent the system quickly with the use of oil or gas firing. A coal-fired boiler came up to pressure slowly, but with oil or gas the steam comes up much more quickly and the air venting has to keep up.



There may have been a vacuum check where the Hoffman air vent is now. That was another coal-era trick- as the coal pile burned down, the air couldn't get back in, so the system kept producing steam at lower temperatures. On oil or gas, the system often shuts down before all the air is out, resulting in uneven steam distribution under vacuum.

Mike20

Thank you

Hello Steam Head

Thank you for the benefit of your Knowledge and experience

I feel much more comfortable with the situation

I will post again when the system has been tested and let you know what happens.

All The best

Mike G