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    Remove pump and traps? (6 Posts)

  • Patrick_North Patrick_North @ 6:05 PM
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    error

    This post was edited by an admin on November 16, 2012 6:06 PM.
  • Patrick_North Patrick_North @ 6:19 PM
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    Whoops- here's my question.

    This is very awkward for me to explain, so apologies for the wordy post.
    Three (church)buildings in a row- let’s call them A, B, and C. They sit on a hill- A is the lowest, C the highest.
    Steam boiler in A serves both building A and C- this is one pipe. A large main passes through the basement of B and continues underground for several yards before entering building C. The main is vented, then drops into a return and goes back down the hill. Currently, the boiler in building A has a condensate pump, but I don’t believe it needs it. Certainly there’s adequate gravity involved!
    However, here’s what gives me pause. When the condensate returning from building C enters the basement of B (about waist height) it is dripped through an F&T before dropping to the ground.
    I’m wondering if I remove the condensate pump if I can then also remove the trap. Removing the pump would mean my condensate return is dry on one end and wet on the other. If the return was wet the entire length this would make perfect sense, but this weird “first it’s a dry return then it gradually becomes a wet return” has me spooked. Any problems you can think of from doing this?
    Thanks,
    Patrick
  • jumper jumper @ 6:51 PM
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    which way ?

    Which way does the supply main slope in buildings A & C ? Up from the boiler or down ?
  • Patrick_North Patrick_North @ 7:06 PM
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    Main slope

    It's tricky.
    From A through B it's parallel flow.
    As it leaves the B basement it drops down to about waist high, and here it is dripped through an F&T trap into the condensate return. I'd keep this trap.
    From this point to C (where it travels underground) it appears to be counterflow.
    Thanks,
    Patrick
  • Steamhead Steamhead @ 8:53 AM
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    If there is more than one drip

    to a return line, the drips have to be isolated from each other. This is to keep steam from flowing into the return. We usually do this by using a wet return, where the water standing in the return provides the isolation.

    Currently, the F&T traps provide this isolation. The Dead Men called this setup a "non-pressurized return" since the steam traps keep the steam pressure from reaching the return, resulting in a "B" dimension at each drip instead of an "A" dimension. Often, a system with non-pressurized returns would also have a Return Trap, to make sure water could return if the boiler pressure got too high. Nowadays we'd use a Vaporstat for this.

    It's not a good idea to just do away with one trap, since it sounds like you'd end up with steam pressure or wet-return pressure at the outlet of the remaining trap. In this case, you'd only have the static height at the trap to provide enough ΔP for the trap to work. This may not be enough, so I'd look at doing away with both traps.

    Whether you can do away with the traps depends on whether you can isolate the drips another way. It sounds like both your drips are in the basement of B. If the return at this point would be wet without the pump, would have enough standing water to isolate the drips and still have enough "A" dimension between the water level in the return and the lowest steam-carrying pipe, then the traps could go.

    If the traps had to stay, you would need enough "B" dimension at this point so the condensate could return without assistance from the pump. You might need a Vaporstat to keep the pressure low enough for this to happen.

    Measure everything up and work it out both ways, then decide.
    "Reducing our country's energy consumption, one system at a time"

    Steam, Vapor & Hot-Water Heating Specialists

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    Baltimore, MD (USA) and consulting anywhere.
    This post was edited by an admin on November 17, 2012 9:04 AM.
  • Patrick_North Patrick_North @ 1:17 PM
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    Can I at least remove the final trap?

    OK, I think I’m following you. Let me see if I’ve got this.
    I’ve currently got F&T traps at 1, 2, and 3. Now assuming I remove the condensate pump, the (currently) dry return will at some point near the boiler become a wet return. If (accounting for operating pressurization) the return is wet where trap 1 drips in, I could remove it, right? Same goes for 2 and 3. Because the boiler and these critical points are in different buildings, it’s going to be tough to determine.
    Regardless, knowing that the return will be wet at the boiler, if I kept the traps at 1 and 2, I could remove the one at 3, right?
    Thanks,
    Patrick
    This post was edited by an admin on November 17, 2012 1:18 PM.
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