Placement of F&T Traps

seanvalentine · October 14

Over the last three years I carefully restored the steam heating system in my home with the help of “The Lost Art of Steam Heat” and Ryan at New England Steam Works in Rhode Island.

My heating system was completely non-functional when I moved in and it was a major undertaking. The biggest problem being that the boiler was twice the size that it needed to be and all the wet returns were either rotten or improperly piped. After replacing all of the wet returns and refreshing all of the steam traps and f&t traps along with removing two sections of the boiler to size it properly, my steam heat is working perfectly throughout the 27 radiators in the home.

Here is my dilemma. I need to move one of my wet returns to allow me to put in a door through a wall where there was not a door before. I have two options. I can either run this wet return back all the way around to where it reaches the boiler independently and below the water line or I can bring it over to the next room where there is another f&t trap that returns back the boiler. However, it will not be below the water line at this point and the two f&t traps would be connected above the water line. I’m pretty sure this is a major no-no. Please let me know your thoughts.

Jamie Hall · October 14

Maybe. There really are too many possible situations to give a firm answer.

Is this F&T inlet connected to a steam main or steam main extension, or is it connected to a dry return? What is the source of the condensate which it is handling? If it is connected to a steam main or steam main extension, how much lift are you requiring for the condensate from the outlet, and what is the normal operating pressure (not cutout pressure) of the system? Is it also functioning as a vent for whatever is connected to the inlet (which I don't recommend, but is common enough).

And so on.

DanHolohan · October 14

You can run it under the door if you’re able to trench the floor. Ideally, the wet return before it goes under should be slightly higher than the side coming out.

EBEBRATT-Ed · October 14

Running it back on its own is probably a sure thing. You can drop under the floor to clear the door. If the pipe carries any air you may need to cross over the door with a small 3/4" pipe for an air passage as the air will not go down under the door…..but you said wet return.

If you can pick up this return and it is high enough above the boiler water line (dry return) you can take it into the other room and drop into the other wet return with a trap

seanvalentine · October 16

Thank you for all of your responses. I will try my best to clarify.

The F&T trap in question is at the end of a steam main run which is vented properly before the F&T trap and drops into a wet return that returns to the boiler well below the water line, but without a water leg. It would not be possible for me to trench underneath the door. the second F&T trap I am referring to is at the end of a separate main off of a different branch if the system all together. It too drops into a wet return well below the water line back to the boiler. The second F&T trap is also vented properly. It is possible for me to connect the two F&T traps together but it would be above the water line. My question is, is it okay for two F&T traps to be connected above the water line and then return back to the boiler? or should I simply reroute the wet return from the first F&T trap back to the boiler below the water line with no water leg. Neither is particulalrly difficult, it just involves additional piping. Currently, All of my F&T traps independently drop into the wet return and have the correctly sized vents before the F&T traps at the end of the mains. I hope this clarifies the question.

Jamie Hall · October 16

Thank you for the clarification.

To further clarify and some terminology. The OUTLET from an F&T is protected from steam — assuming, of course, that the F&T is working. Therefore it is, technically, a dry return, and never sees steam, but carries condensate. If it the trap is an F&T it will not carry air (if it were a crossover thermostatic trap, it would) and so may or may not need venting (the steam main connected to the inlet must be vented separately; an F&T is a miserable air vent).

And the bottom line for you is… ta da! … yes, those pipes can be connected above the water line and then drop; just make sure that there is the correct pitch on the pipe to drain to the drip.

EBEBRATT-Ed · October 16

Yes if both traps are vented properly and the traps are working you can tie the outlets of both traps together with no issue. Its done all the time.

Jamie Hall · October 16

One minor additional comment — be sure that there is enough pressure on the steam main to lift the condensate from the F&T to your new dry return.

Placement of F&T Traps

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