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    does this system look right? (24 Posts)

  • pipeking pipeking @ 10:59 AM
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    does this system look right?

      I am doing the plumbing on this job, it's a 3 story 200+ private rooms for senior living (very elegant). another company is doing the heating and cooling system, and I have some problems with the way boiler room has been piped. I haven't said anything to anyone, but it's just not how I would have done it. here are some pics and a diagram. I left some thing out of the diagram like, sensors, valves, isolators, but the fundamentals are there. take a look then I will give my 2 cents on it.
  • nicholas bonham-carter nicholas bonham-carter @ 11:25 AM
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    "Piping by others"

    Are you concerned by the use of Victaulic joints instead of tried and true threaded, or sweated joints?--NBC
  • pipeking pipeking @ 7:11 PM
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    threaded whoa

     u don't see 6"+ threaded to often anymore, around here anyway. some prefab welded stuff would have been nice with just a few joints left to weld in the field or vic would have been cool. all the scd 40 vic is time consuming.
  • jim s jim s @ 11:48 AM
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    Engineered?

    Was there a set of engineered drawings to adhere to?
  • icesailor icesailor @ 11:58 AM
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    Design:

    Jobs of that scale and complexity are usually designed and specified by a Registered Mechanical Engineer. There are things that look strange to me but then, I'm not a trained engineer. That stamp and ability to write your name over the embossed part of the plan makes them smarter than us. We just get to figure out why it doesn't work and how to fix it. If and when it doesn't work as designed or planned.
    I would have thought that the two boilers would be piped as a true Reverse Return on a primary loop, connecting with two closely spaced tees into the secondary. The "X times Pipe Diameter" method and not the "any old distance apart (like 6', around a corner with another tee in between) method. Or using Bridge Loops with the secondary supply and return on the crossover switched backwards.
    Funny thing about Hydronics, it's awfully forgiving of mistakes.
    Its clever to mount those circulators on their heads. You don't need an extra hanger on the motor and you don't have to worry about the excess heat overheating the end/top of the motor. It is guaranteed to overheat. Unless they are designed that way.
  • JohnNY JohnNY @ 12:09 PM
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    Vic

    Why on earth would someone groove piping for a job like that?

    The diagram doesn't inspire confidence, either.

    You'd be right to raise your concerns with a project manager.

    Where is this job?
  • M Lane M Lane @ 2:20 PM
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    ME's

    I have been a superintendent for the Denver area's largest mechanical contractors for over 20 years; I have performed many projects with the mechanical contract in the tens of millions. So I have seen this sort of thing over and over again. Jobs this big are always engineered. Often, the engineer uses low-wage kids just out of school b/c they just don't have the design budget they want. So we frequently end up with crap like this, assuming the schematic is correct.
    Normally, the companies I work for have their own engineers and significant brains in the pre-construction phase of these jobs (usually while still being negotiated) so that we will quote our own boiler/chiller package within the parameters of the original intent.
    Then we have the power to come in with our own time-proven manifold designs that include primary/secondary loops plus our common tactic of 'First in, Last out" with every redundant unit like boilers, tanks and pumps.
    But in my experience with 200 room +/- retirement homes is that some idiot designed the thing like this and we did not have budgetary room to re-engineer.
    So, how I made my name for myself is that I will start plastering the ME with RFI's pointing out things like one boiler will doing almost all of the work, one pump, etc. Then the architect and owner start to see red flags and I will usually end up getting my way plus some extra dough for the trouble.
    I have also done many large boiler and chiller rooms with grooved pipe. I much prefer real pipefitting and welding, but they work too. The latest trend is for the CAD dept. to design big chunks of manifold for pre-fabrication at the shop, where it is actually cheaper in those conditions to weld than to groove. Then the spools are shipped to the jobsite where we connect the chunks with grooved connections.
    Also, a VFD on the pump greatly reduces the need for a triple duty as balancing is not as important and you can put strainers in the suction diffuser. With VFD'd pumps I'll usually get just a check valve in there.
    The thing is from a liability aspect you don't just say the engineer is an idiot and do it your way. You will get sued into oblivion doing that.
    This post was edited by an admin on January 26, 2014 2:24 PM.
  • nicholas bonham-carter nicholas bonham-carter @ 2:34 PM
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    Manufacturer's recommendations

    Couldn't the engineers at least read the manufacturer's piping instructions, or is that too much to ask?
    There are Knuckleheads at every level it seems.--NBC
  • Steve Whitbeck Steve Whitbeck @ 5:55 PM
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    piping

    IF the system is piped like your diagram then it IS piped wrong.
    First why have a hydraulic separator and not use it. The boilers need to be piped directly to one side of the Hyd Sep and the system gets piped to the other.
    Also the domestic hot water indirect loop must be tied into the boiler loop supply line before the Hyd Sep so it receives the hottest water possible.
    And as far as engineered drawings I have had to train a few engineers.
    They tend to use boiler plate drawings without thinking.
  • icesailor icesailor @ 6:13 PM
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    Notice:

    You've noticed that.

    What kind of a plate is a Boiler Plate?
  • bob bob @ 6:40 PM
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    Hydraulic separator

    Steve, that doesn't look like a hydraulic separator I think it's a Rol-air-trol or Taco's equivalent .
    bob
  • pipeking pipeking @ 7:06 PM
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    these are my issues

     oh yea, how have u guy been!? I know it been a while!  :}
     I know the pics are hard to follow, but the diagram I drew is exactly how the primary/sec piping is set up. so with the closely spaced tees not closely spaced, and an elbow in-between, and the differential by-pass in-between, was the elephant in the room. I don't think the hydraulic separator is a tru separator, its just an air separator with a strainer. the whole job was vic, and I'm ok with the boiler room being vic its just a lot of feild work. at the end of the secondary loop it is not "looped" together but there is are differential pressure sensors for the by-pass in the boiler room. there r no 3 duty cuz of the VFD's, just suction diffusers and checks. I do like the way the pumps r hung above the boiler and the stanch the built for the chiller pumps. the circuit setters on the primary I don't get, shouldn't the pumps be sized accordingly (thinking the only reason they r there cuz the pumps could be to big).I will try to get a pic of the print to see what's what.
      also the engineer has circuit setters on my domestic hot water mixing valve too. I have never seen that before! there r a few water heaters that don't have a recerc line or anything fancy: just a hot water heater and a thermostatic mixing valve (symmons 400&500) and the print shows a circuit setter on the cold water inlet of the mixing valve. It's been a while since I read the literature on these bigger mixing valves so I opened it up (3 pages wow) and there ain't nothing in there, or water heater's literature about that; like I said never seen that before.
  • Steve Whitbeck Steve Whitbeck @ 7:54 PM
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    piping

    Boiler plate is a term I heard years ago. It is just a piping template.
    Roll a troll has the piping connections going into the side of the tank at an angle to induce a spiral flow inside the tank.
    I didn't look long enough at the pictures. I see that the tank doesn't have 4 tapping's
    I looked mainly at the diagram.
    If that is a roll a troll or equal then the piping still isn't right.. Then the boiler loop needs to be piped primary / secondary with closely spaced tee's - not spread apart like in the diagram. And the indirect still needs to come off of the boiler supply pipe before it goes to the main.
  • pipeking pipeking @ 8:06 PM
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    steve

    there is no indirect. just to boilers and a chiller. domestic hot water is being done by my company and we r using high ef. storage tanks.
  • Steve Whitbeck Steve Whitbeck @ 9:30 PM
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    indirect

    I can't blow up the diagram - I thought the piping going off to the left on the diagram had Initials for domestic hot water. AKA - indirect.
    BOY - I am batting zero today.
    Sorry

    I would have piped the chilled water primary / secondary also. But the tee's for the chilled water would have been after the boiler tee's - less cold water induced into the boiler loop even with the spring checks.
    This post was edited by an admin on January 26, 2014 9:36 PM.
  • gennady gennady @ 9:49 PM
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    piping

    This system is piped completely wrong.
    -no point of no pressure change.
    - boilers are piped in a way that their pumps are pumping into itself. i do not see system pumps
    - differential pressure bypass is in wrong place.
    and so on

    whole thing looks like a joke
    Gennady Tsakh

    Absolute Mechanical Co. Inc.
    www.AbsoluteMechanicalCoInc.com
  • VictoriaEnergy VictoriaEnergy @ 1:15 AM
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    Boiler Plate

    The term "Boiler Plate" is used by lawyers to describe standardized terms and conditions in binding contracts that have been repeatedly argued over and upheld in court. 

     As if the contract can't be torn up because it was written on plate steel instead of paper.
    Home Owners Please Note:


    You are receiving advice from some very skilled pros completely free of charge. One of the reasons I participate is to sharpen my own troubleshooting skills. So; did we get it right? I would be grateful if you extend this courtesy back by posting the final outcome of the issue you are inquiring about. Thanks
  • M Lane M Lane @ 7:04 AM
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    How I'd do it

    4 a.m. dwg, Probably do something different at building S & R for the chiller water
    This post was edited by an admin on January 27, 2014 7:04 AM.
  • Mark Eatherton Mark Eatherton @ 9:50 AM
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    Close, but not quite...

    To the original poster, to their credit, the engineers may have drawn it correctly, but due to space limitations, the installer did not meet their intent. Without seeing the engineers drawings it is impossible to say. Regardless, this system is going to have a lot of problems.

    Due to the fact that they put extra pipe and fittings between the two secondary tees, you will experience flow through the chillers and boilers even when they are in the OFF position.

    Also, if you have a VFD, and a properly applied pressure differential SENSOR, that is controlling the pumps, then you DON"T want a pressure differential bypass controller anywhere in the circuit. The pumps will see the bypass as a "hole" in the system and will run at a significantly higher speed trying to fill this hole in.

    This is not rocket science, but you do have to pay attention to detail in order for things to get along, and play well together. WIth it being a 2 pipe system, it is obvious that you will either be in heating mode, neutral or cooling mode, but never both heating and cooling mode. That may not work well for your building, depending upon the buildings use, solar exposure, internal gains, etc.

    M. Lane, too many check valves. In a good and true primary secondary system, it is common to have reverse flow in the tweener sections, and it is acceptable. It will cause some mixing, but during the shoulder season marginal calls, its effect is negligible. And as I pointed out to the original poster, no pressure activated bypasses in a system with variable speed pumps.

    I like the KISS theory. The main distribution system with the VFD pumps pushing to the loads, with closely stacked tees for each of the heating or cooling branches. VFD pumps pumping away from the air separator and the PONPC, and all other pumps pumping away from the common loop connected to the PONPC.

    My assumption is that the terminal units have 2 way valves on them, and that assumption could get me into trouble. Tells us about the terminals and how they are being controlled.

    Lastly, even if the system was "engineered", if you knowingly install an improperly designed system, hoping to make money on the change orders, most engineers have a clause in their contract that DOES affect you. You are also culpable for the changes required to correct the system. It would be tough to prove knowledge before the fact, but in todays society and internet, it is possible…


    Tread lightly, and document EVERYTHING...

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • SWEI SWEI @ 10:16 AM
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    Check valves on multiple boilers

    I've been omitting these for several years now and have not seen problems.  Nice to know I'm not all wet! 
  • pipeking pipeking @ 4:58 PM
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    SORRY

     couldn't get the print today but I will.
      mark, they don't  have valves on the primary tee's so there won't be flow in cooling mode ( I know I left them out of the drawing, but u can c them in the pics). I to was questioning the 2 pipe system for heating and cooling, I am sure they will need to cool and heat at the same time and won't be able to.
     what kind of problems do u think they will have. I think that it won't be very efficient on the electrical side (pumps fighting), but what about hydroniclly?
  • Mark Eatherton Mark Eatherton @ 9:22 PM
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    Ghost flow….

    Due to the fact that they put fittings and pipe between the two secondary tees, and the boilers are piped in parallel, you WILL have flow though the boilers and the chillers, even when their respective pumps are in the off position.

    Secondary tees MUST be as close to each other as possible to avoid creating a pressure differential between the tees.

    There are also some basic rules of straight pipe before and after take off tees, but not nearly as critical as the need to make certain that the tees are as close to each other as possible.

    And then there's the "hole" in the system being caused by the pressure differential bypass control valve… Might as well not even have the variable speed pumps…

    I'd generate a drawing, but I am headed for Las Vegas to speak at the Surfaces convention, so won't be able to do so until Wednesday.

    Generally speaking, 2 pipes system MUST have a "neutral" position to allow the chilled or hot water a chance to dissipate their heated or cooled fluids prior to starting either the chillers or the boilers. Otherwise, you may cause some serious damage to the equipment.

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Mark Eatherton Mark Eatherton @ 5:20 PM
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    Solutions...

    There are no less than 100 ways for different people to pipe the same system. Here;s my idea of ultimate simplicity. Numerous valves and the expansion tanks are missing because the old PC decided to throw up on itself right near the end of the drawing, but I think you'll get the gist.

    Got questions?

    ME

    PS, sorry for the delay. Busy busy busy...
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • M Lane M Lane @ 1:34 PM
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    A version for critique

    I am a huge fan of 'first in, last out' with multiple pieces of equipment. Not a huge fan of 3-way valves though, as all the old apartments in Denver I see them in they are essentially manual only and not reliable. This drawing shows what I take the parameters were with this job. I am more used to separate expansion tanks and system pumps, but that all adds cost. Also, I do not currently work for who made the iso pad I just used. If it is too close to advertising let me know. Tried to cover it.
    This post was edited by an admin on February 2, 2014 2:01 PM.
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