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Vacuum pump piping

bigpete638bigpete638 Member Posts: 30
Hello,
A maintenance working changed the pumps on this vacuum receiver and was pulled from the job. I was asked to reconnect the system but can’t find any literature on this particular unit. Any information is greatly appreciated.

Comments

  • bigpete638bigpete638 Member Posts: 30
    I can see where the discharge of the pumps tie in and where it connects to the return to the boiler. There is a half union on the line next to it. Is there supposed to be a vent?
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  • bigpete638bigpete638 Member Posts: 30
    I’m not sure where the bottom line coming off the unit tied in.
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  • bigpete638bigpete638 Member Posts: 30
    I order Dan Houlahan’s book and just started reading it. I’m a steamfitter but have always been a new installer. Never piped a vacuum pump before.
  • ScottSecorScottSecor Member Posts: 234
    @bigpete638 It's not that simple to explain. Here is a starting point:
    http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/DN0134E.pdf

    From your photos it appears you have ITT/Domestic Pump/Hoffman unit, similar to the link I provided above. Yes, the tank has to be vented, typically well above the top of the boiler level. Yes the condensate has to be pumped back to the boiler, typically well below the boiler water line.
  • ScottSecorScottSecor Member Posts: 234
    The vertical pipe coming off the two check valves above the tank are likely the condensate return that would go to the boiler. The vertical pipe coming off the top of the tank would likely be the vent (to keep the tank from ever pressurizing. The other opening in the tank is for the return lines to tie in. The thing under the silver gauge is a basket strainer (that occasionally get clogged), I urge you to clean it and prime it before starting unit for the first time. Finally, those pump motors are far from original, be real careful with them as rotation is critical and they may not be the correct motor for your application.

    Might consider reaching out to the local ITT/Hoffman/Bell & Gossett (now Xylem) representative for some help and perhaps repair parts.
  • bigpete638bigpete638 Member Posts: 30
    Once again thank you. Several buildings here were already converted from vacuum return to gravity via condensate receiver tank. The piping was never changed either. Lots of problems but they’re ridiculous about cutting corners and saving money.
  • ScottSecorScottSecor Member Posts: 234
    One more thing to consider, based on the owner cutting corners and the age of the steam traps in your photos, I'd be very careful. As you may already know, vacuum pumps do not work well with even slight amounts of live steam. Unless all or at least most of the steam traps have been rebuilt or replaced, I'd suggest not running the vacuum side just yet.
  • bigpete638bigpete638 Member Posts: 30
    I just found out they are no longer using it as a vacuum system and are just hurling water to the boiler.
  • jumperjumper Member Posts: 1,311

    I just found out they are no longer using it as a vacuum system and are just hurling water to the boiler.

    Properly designed vacuum systems are rare.

  • bigpete638bigpete638 Member Posts: 30
    Trying to locate these traps online for replacement. F&t traps with an exterior thermostatic element? The supervisor did mention he wanted to restore the vacuum system as opposed to gravity.
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  • PumpguyPumpguy Member Posts: 354
    @bigpete638, you will find in Dan's books that it's never a good idea to remove a vacuum pump from a system that was originally designed for a vacuum return.

    Unfortunately, this happens all too often, resulting in a need to operate with higher steam pressure, uneven steam distribution, longer warm up times in mild weather, and increased fuel costs.

    Can you tell us what is the returning condensate temperature and operating steam pressure on this system? If over 2 or 3 PSI, its too high. Even the Empire State Building, which is a vacuum return system, doesn't go over these pressures.

    To elaborate on @ScottSecor's comments, If the condensate temperature is much over 165*F, the performance of the vacuum pump will fall off. I would consider 170-175*F to be a maximum condensate temperature for a vacuum return system. Lower is always better for efficient vacuum operation.

    High condensate temperature usually starts out when steam traps fail and allow live steam to enter the return lines. This can be exacerbated by an increase in steam pressure, which causes an increase in the mass or volume of steam that leaks past the bad trap(s).

    Depending on the particular condensate pumps now installed, it is possible to continue to use these in conjunction with a separate stand alone vacuum pump. You don't always need to install a whole new vacuum condensate return pump set. Feel free to contact me directly for more details on how this can be done.

    Specializing in vacuum pumps for steam heating systems, especially older Nash Jennings units. We build new ones too!



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  • bigpete638bigpete638 Member Posts: 30
    I just started this position two months ago. They actually have been dumping condensate down the drain I believe. Couldn’t tell you the temperature but I’m sure you already have a good idea what it was.
  • bigpete638bigpete638 Member Posts: 30
    There are accessible traps to replace but the surrounding piping is old. If a thread snaps(which happens regularly here) I’m dealing with asbestos(which we can’t touch because they don’t have funds to abate).
  • jumperjumper Member Posts: 1,311

    I just started this position two months ago. They actually have been dumping condensate down the drain I believe. Couldn’t tell you the temperature but I’m sure you already have a good idea what it was.

    I've seen quite a few industrial facilities dump condensate. Factory sewer has drains all over. But it looks like in your case they have piping to return condensate to boiler room?

  • bigpete638bigpete638 Member Posts: 30
    They do have return piping but they disconnected the tank and ran the line directly back to a tempering tank. I’ll be tying back into the boiler here soon.
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  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 5,715
    @bigpete638
    Those are Dunham-Bush traps but I don't think they are made any longer.

    You could try Tunstall associates in Chicopee, MA or Barnes & Jones in Boston for parts to repair those traps.

    Other than that replacement is a nasty Repipe. I had a building in Connecticut with 600 of those traps. Nothing fits even close. best option we found Tunstall has some in line F & T traps that you can pipe in fairly easily but you have to watch the capacity. The inlines have lower capacity as I recall

    You can put other traps in of course with more repiping
  • bigpete638bigpete638 Member Posts: 30
    Can I use f&t traps in a vacuum system?
  • bigpete638bigpete638 Member Posts: 30
    I’m planning on replacing the whole manifold along with all the traps. I just need to find out which traps would be best suited for this application. The Dunham bush traps look just like f&t s with an external Thermo dynamic element. Was wondering if a f&t trap would also function in a similar matter?
  • ScottSecorScottSecor Member Posts: 234
    I am not certain but bit I believe the existing traps in your photos are F&T traps, just that the "T" (thermostatic) is external instead of the more typical internal type. Yes, a normal F&T trap will work fine.
  • bigpete638bigpete638 Member Posts: 30
    I’m am indebted to this site. Thank you for all your help.
  • SteamheadSteamhead Member Posts: 12,925
    Dunham-Bush is still around, now called MEPCO. AFAIK they still make trap parts. If not, what @EBEBRATT-Ed said.

    And listen to what @Pumpguy and @DanHolohan say. Pumpguy is the best when it comes to vacuum. When you see them say "it's never a good idea to remove a vacuum pump from a system that was originally designed for a vacuum return" you may take that as gospel.

    Where are you located?
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
  • bigpete638bigpete638 Member Posts: 30
  • bigpete638bigpete638 Member Posts: 30
    im reluctant to leave an exact location. I’m hired on probation at the moment and don’t want to cause trouble.
  • neilcneilc Member Posts: 661
    for posting and studying here?
    you ought get tenure, and a raise.
  • bigpete638bigpete638 Member Posts: 30
    Lol im sure the establishment I’m working for would be subject to fines and or imprisonment had these conditions be publicly known.
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