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steam questions

1. A "return trap" is basically a pressure-powered pump that helps condensate get back to the boiler. A "trap on the return" lets air and water pass while stopping steam. Some installers put a trap right before the condensate tank inlet, but that's wrong.

2. On a 2-pipe Vapor system, there should be no vents on the rads at all. Air passes into the returns and is vented at one or more central locations, usually near the boiler. Sometimes the steam mains are vented thru radiator or F&T traps piped between the steam main and the dry return. Air passes thru the traps but they close against steam.

You do have to know where to look for the vents. Sometimes they are radiator traps or F&T traps. If a return pump and tank are used, all returns should pitch down toward the top inlet tapping on the tank, and the tank vents the air thru an open pipe.

In no case should these devices be hidden behind walls or ceilings. Provide access hatches for servicing them.

3. A Float & Thermostatic trap does the same thing as a radiator (thermostatic) trap- it lets air and water pass, but closes against steam. But it has two mechanisms: the float rises with accumulating water and opens a valve to let it out, while the thermostat opens to let air pass but closes on temperature when steam reaches it. In this way, it can handle a lot more condensate than a plain thermostatic trap.

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  • Timco
    Timco Member Posts: 3,040
    Just a few questions...

    In reading about steam systems, I have noticed that some I have looked at have both a return trap as well as a feed pump...are both needed? Can I get the definition of 'F&T trap'? Are the vents on the rads in a 2-pipe vapor system my main vents? Most systems I have looked at have the mains & pipes in walls & enclosed ceilings. How does one find the vents? Is this done by knowing where they need to be?

    Thanks, Tim
    Just a guy running some pipes.
  • Timco
    Timco Member Posts: 3,040

    Thanks Frank! Of the last three systems I looked at, one had the return trap and condensate pump, and vents on 6 rads in the 30 or so apartments ( two pipe wit traps on all rads). One had a condensate pump and no vents visible anywhere, and one has two pipes and traps, but fin type convectors. The two that are working have water hammer. I did not hear back yet on fixing the hammer, but I am learning that all traps may need to be serviced as new ones can mess with bad ones. I am mostly interested in identifying them....

    Thanks again, Tim
    Just a guy running some pipes.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    One of these days

    I might take a trip to Utah- never been there.....

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