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This weeks case, The difference between a condensate tank and boiler feed system

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RayWohlfarth
RayWohlfarth Member Posts: 1,518

There is no mystery to solve this week. I wanted to explain the difference between the two as I had a contractor who got a boiler replacement project and tried using the old condensate tank for the two boilers. They had all sorts of issues with the boilers water levels. I will post it Friday

Ray Wohlfarth
Boiler Lessons

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,089
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    LWCO operates a boiler feed tank

    Float switch operates a condensate tank

    I remember installing a WM78 to replace an old Mills boiler from the early part of the 1930s . The Mills operated with a condensate return tank, but I swapped it to be a Boiler feed tank and prayed that the tank was large enough. (boiler feed tanks are usually a little larger for the same application). It was! I made the float operate the auto water feed, and the LWCO operate the pump on the tank.

    Works great, still doing the job today after 20+ years.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Pumpguy
    Pumpguy Member Posts: 663
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    When sizing a boiler feed tank, its typical to provide from 10 to 20 minutes of steaming time from boiler start up until condensate returns to start the recirculation cycle.

    Older boilers had large water storage capacity so usually a condensate pump was all that was needed. Many of today's boilers don't have the water storage capacity so a boiler feed tank and pump(s) now provide that function.

    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • jumper
    jumper Member Posts: 2,289
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    In commercial & industrial settings condensate handling sometimes was pretty fancy. Like an elevated tank to feed boiler. Pretty interesting how to lift de-gassed water.

  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,545
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    This is how I (painfully) learned the difference.
    https://heatinghelp.com/news-and-media/dead-men-tales/what-ray-taught-me/

    Retired and loving it.
    EdTheHeaterManMad Dog_2Intplm.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,620
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    I always used 20 min minimum for condensate to come back and then I would look at the building. A compact 6 story apartment building or a 1 story factory return condensate at different rates. So for me it was 20 min minimum pus an educated guess based on the building.

  • retiredguy
    retiredguy Member Posts: 915
    edited May 17
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    Good educational story Dan. There are a lot of contractors that do not know the difference between the two of them. As I have said before, most of my work was on larger steam systems and on those you have to know the difference and when and where to use them. On any installation where we replaced an old steam boiler with a large water capacity with a newer style steam boiler that had a much smaller water capacity I always recommend a "condensate feed tank" in lieu of a "condensate tank" with an explanation as to why this was necessary. If the customer refused the extra cost of the feed tank then it was on him if there was a problem with the boiler's water level.

    Mad Dog_2
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,518
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    I always use 20 minutes but have been burned before. We discovered the system used to be a vacuum return and converted to gravity. Dan, I feel your pain. I thought I had enough slides for the seminar and came up short by an hour and half. Of course there were no questions so I told stories about my experiences. Awkward. Anyway, here is the link to the video.

    Ray Wohlfarth
    Boiler Lessons
    CLambIntplm.
  • jumper
    jumper Member Posts: 2,289
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    How did steam locomotives control water level?

  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,106
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    Iron Mike Tyson : "Everyone has a plan till they get punched in the face..."

    Ray punched you in the face...in a nice way..Dan...Ha ha..Hey..The ONLY way you really learn to fight (teach) is to get in the ring and bang. As you always said Dan, Sometimes, you just gotta be the guy that's shows up! You'll figure the rest out as you go...

    We all started out as 'That Dopey Kid."

    What you gave all of us disciples is the Paradigm To Listen, learn Read On..get IN there...figure it out...struggle & wrastle to you win…dream big....never let up....Mad Dog

  • Jamie Hall
    Jamie Hall Member Posts: 23,436
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    Very carefully — and manually. If you look at pretty much any steam locomotive's backhead — the part of the boiler that sticks into the cab — you will see two water level glasses — sight glasses — just as are used on heating boilers. You will also almost always see three try cocks (soometimes six). You will also find at least one and usually two handy dandy valves to control the injectors. The fireman's job — among other things — is to ensure that the boiler water level is at, and stays very close to, the centre of the sight glasses. Now steam locomotives (except for some interesting South African designs) are consumptive — that is, they don't condense and recycle the steam — so the steam usage and hence the water usage is determined by the power demand on the engine. So… a good fireman who knows the route can get a pretty good feel for how fast water is going to be used and set the injector valve or valves accordingly.

    You don't want too little, particularly (oddly) going downhill, as the crown sheet — the part of the boiler at the back over the firebox — might get uncovered and that is just not good news. On the other hand, you don't want too much, as then on older engines (not modern superheated ones) you stand a chance of priming — getting liquid water in the steam line — and if that gets into a cylinder that can ruin your whole day, too… (Southern Pacific's cab forwards had the opposite problem — or sort of both at once. Climbing Donner Pass the water would get low over the crown sheet, but at the same time the water might be too high at the steam dome… those firemen had to be really good!)

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • retiredguy
    retiredguy Member Posts: 915
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    @jumper , steam locomotives had a water storage tank as part pf the coal car hopper and a steam powered water pump. Remember in the old movies that the train would stop at a storage tank and fill the tank that was part of the coal car. If the pump went bad or malfunctioned that will occasionally happen with a high pressure boiler there was usually a Penberthy Injecter feed control that most boiler operators had no idea how to use.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,089
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    Penberthy Injector feed control

    Just guessing here but I can see how steam pressure can pressurize the container of water to force the water from the container to the desired location. But that seems somewhat problematic with keeping the container from overpressuring. Another way might be to use the steam pressure to cause a venturi to make the water flow as the steam flows into the valve, allowing the exit of the injector to cause both steam and water to enter the boiler. Either way, it is a pretty interesting way to move the water from the tank in the fuel car, to the boiler if the pump fails mid route. 

    Am I Close?


    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Jamie Hall
    Jamie Hall Member Posts: 23,436
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    Second guess, @EdTheHeaterMan . The steam injector — which was used on almost everything — is a simple venture device which uses high pressure steam to — by magic, it's always seemed to me! —- pump water from the tender into the boiler. It was supplemented by — or on some engines replaced by — a mechanical feedwater pump.

    Either way, the fireman controlled the flow with the injector steam valve.

    And no, the tender was never pressurized with anything. Just pretty much gravity to the injector pumps and on into the boiler from there.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterMan
  • jumper
    jumper Member Posts: 2,289
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    Injector turns velocity from steam jet into pressure. More pressure than steam originally has. So devise is considered wasteful of precious steam. Inefficient. Evidently steam powered positive displacement pump is more efficient. Either way I agree with Jamie that it must be difficult to maintain proper water level.

    That is why I asked question. Seems to me that neither conventional (centrifugal) condensate or feed pump is ideal. For one thing switching multi-horsepower motors on & off is not nice.

    Mad Dog_2
  • Pumpguy
    Pumpguy Member Posts: 663
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    Attached is some interesting text on locomotive boiler feed pumps copied from the book A HISTORY OF THE AMERICAN LOCOMOTIVE, ITS DEVELOPMENT: 1830 - 1880, by John H. White, Jr.

    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
    Mad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,106
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    We think engines, turbines, boilers HP are cool now...Imagine when they were first being developed? Who towns would show up & marvel..I'm sure Dan wrote quite a few articles on this. Mad Dog

  • RayWohlfarth
    RayWohlfarth Member Posts: 1,518
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    @Mad Dog_2 and @DanHolohan I certainly didnt mean to sound like that. I apologize if it did.

    Ray Wohlfarth
    Boiler Lessons
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,545
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    Not at all!

    Retired and loving it.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,089
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    I think that it is very appropriate that a guy named RAY posted this video on condensate pumps and boiler feed pumps on this website. Especially since the guy that started this website learned the difference between a boiler feed pump and a condensate pump from another guy named RAY.

    It's like there is a RAY of sunshine beaming from one generation to the next.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Sylvain
    Sylvain Member Posts: 147
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    a little bit of history:

    naval boilers

    you won't sail in a hurry (5 hours notice):

  • RayWohlfarth
    RayWohlfarth Member Posts: 1,518
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    @EdTheHeaterMan Thanks for Ray of information

    Ray Wohlfarth
    Boiler Lessons
    EdTheHeaterMan
  • jumper
    jumper Member Posts: 2,289
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    Naval turbines have their uses. So do compound engines.

    But probably most successful steam engine for ships were the uniflows in WW II baby aircraft carriers. Why weren't any salvaged?

  • Jamie Hall
    Jamie Hall Member Posts: 23,436
    edited May 19
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    Uniflows were also used quite frequently on various Lake carriers.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • jumper
    jumper Member Posts: 2,289
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    »Uniflows were also used quite frequently on various Lake carriers.«

    Anybody know details? I believe those carriers produced 900 hp per cylinder.

    I guess steam pressure was much higher than on lake and river steamers?

    Who can forget boiler on AfricanQueen?

  • jumper
    jumper Member Posts: 2,289
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    Further research suggest opposite. LakerBadger was 485 psi. BabyCarrier only 285 psi.

  • PRR
    PRR Member Posts: 156
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