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  1. #1
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    Filling system after drained

    Am I right in thinking, once you have drained a system, to refill a 2 pipe chilled water system, you open the hose connection / gate valve at the top on the roof at chiller or highest point in loop, turn the make up water pump on, wait until all air purged and close the gate valve at top and than proceed to turn on the main pump?

    If you throw a boiler into the equation and change over valves are used in this 2 pipe system , would you leave both of those valves open when filling the system? (opposed to closing the ones for the chilled water and opening the ones for heating) ??

  2. #2
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    Your correct on filling to vents at the highest point. Id open the heating changover valves and close the cooling valves before i fill it. With out knowing the job, i wouldnt want to have any water that has the potential to freeze the chilled water system in the winter. Make sure you also dont run hot water through the chiller.
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  3. #3
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    that, and once you have water coming out of your vents, close them, and turn the pump on for about 10-15 minutes, shut it off, let it settle for about 10 minutes, then check your vents again. continue the process until you've removed all the air.

    be sure to check your expansion tank and makeup system also.

    If you have a large, complex system with a gauge on the leaving side of the makeup, watch your gauge as you fill. If there are still air pockets out in the system, you'll see your gauge drop, and then rise again, as the water pushes the pockets around. it may take a few hours to get all the air out, depending on the system.

  4. #4
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    Quote Originally Posted by 71CHOPS View Post
    that, and once you have water coming out of your vents, close them, and turn the pump on for about 10-15 minutes, shut it off, let it settle for about 10 minutes, then check your vents again. continue the process until you've removed all the air.

    be sure to check your expansion tank and makeup system also.

    If you have a large, complex system with a gauge on the leaving side of the makeup, watch your gauge as you fill. If there are still air pockets out in the system, you'll see your gauge drop, and then rise again, as the water pushes the pockets around. it may take a few hours to get all the air out, depending on the system.
    Just to re state ..

    Let's say it's a 3-4 story building.. Makeup pump in basement with city water there to fill make up tank.... I am only opening one vent on roof and proceed to fill makeup tank in basement and have makeup pump run until water seen coming out of vent on roof or high point. Bump the main pump for 10-15 minutes .. let settle rinse and repeat until all air is out of the system..

    I never thought a makeup pump had enough power/pressure to push water up 3-4 stories..

  5. #5
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    make up pump or a circulating pump?....two different animals.

    and you should have an expansion tank, not a makeup tank, unless it's an open system. the expansion tank should be isolated from the system for filling.


    once a system is full, it's more like a ferris wheel rather than "Pushing", although head is a factor....read up on "Pump Laws" if you're more interested in the subject.

  6. #6
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    Quote Originally Posted by superheatmaster View Post
    I never thought a makeup pump had enough power/pressure to push water up 3-4 stories..
    I guess I don't really know what a "make up pump" or a "make up tank" is, but your static water pressure should only have to be about 20psi (actually a little less) to get the water up to the top of a 4 story building. As long as the pump can do slightly more than that, then you are good.

    Is this "make up tank" for adding glycol and/or chemicals to the system? That I could understand. Otherwise I would think city water pressure and no make up tank would probably be good enough.

    This isn't a steam system that you're playing with, is it? I know you said chilled water, but sometimes there might be a steam to hot water converter tied into the mix, and the steam boiler would certainly have a tank and a pump in order to keep the boiler filled up. This would be completely separate from the water in the rest of the building pipes though.
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  7. #7
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    Quote Originally Posted by 71CHOPS View Post

    and you should have an expansion tank, not a makeup tank, unless it's an open system. the expansion tank should be isolated from the system for filling.
    Ahhhh... I forgot about the "open expansion tanks". I've seen one of those a long time ago in the attic of a house that was a little over 100 years old. It was an open steel tank with a float valve in it that maintained the correct water level. These types of systems certainly aren't very common, well unless you are talking about a pool boiler, which is kind of the same idea. No real expansion tank needed in either one.

    edit... I guess a cooling tower could qualify as turning it into an open system too under some circumstances. So what type of system is this, exactly?
    Last edited by ammoniadog; 11-03-2019 at 04:12 PM.
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  8. #8
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    Quote Originally Posted by 71CHOPS View Post
    make up pump or a circulating pump?....two different animals.

    and you should have an expansion tank, not a makeup tank, unless it's an open system. the expansion tank should be isolated from the system for filling.


    once a system is full, it's more like a ferris wheel rather than "Pushing", although head is a factor....read up on "Pump Laws" if you're more interested in the subject.
    Make up pump... say 1/2 hp there is an expansion tank.. When I say make up tank, its a barrel say 50 gal .. has makeup pump underneath ... an can be fed city water.. its for adding water / glycol

    The expansion tank was a bit ways way next to their boilers..

  9. #9
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    Quote Originally Posted by ammoniadog View Post
    I guess I don't really know what a "make up pump" or a "make up tank" is, but your static water pressure should only have to be about 20psi (actually a little less) to get the water up to the top of a 4 story building. As long as the pump can do slightly more than that, then you are good.

    Is this "make up tank" for adding glycol and/or chemicals to the system? That I could understand. Otherwise I would think city water pressure and no make up tank would probably be good enough.

    This isn't a steam system that you're playing with, is it? I know you said chilled water, but sometimes there might be a steam to hot water converter tied into the mix, and the steam boiler would certainly have a tank and a pump in order to keep the boiler filled up. This would be completely separate from the water in the rest of the building pipes though.
    Its just a tank .. Like a barrel that we can dump glycol in and it will get pumped into the system... n a perfect world when set to automatic the makeup pump would automatically engage and add glycol/water whenever the system needed.

  10. #10
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    a pic of the make up tank... makeup pump is under that barrel.



    Attached Thumbnails Attached Thumbnails 20191102_101333.jpg  

  11. #11
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    dunno why pic comes out sideways when posting..

  12. #12
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    Ahhh, you should have included originally that you’re filling a glycol system. Yes you have a makeup tank and pump system then.

    Are you filling with city water or glycol?

  13. #13
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    Quote Originally Posted by ammoniadog View Post
    Ahhhh... I forgot about the "open expansion tanks". I've seen one of those a long time ago in the attic of a house that was a little over 100 years old. It was an open steel tank with a float valve in it that maintained the correct water level. These types of systems certainly aren't very common, well unless you are talking about a pool boiler, which is kind of the same idea. No real expansion tank needed in either one.

    edit... I guess a cooling tower could qualify as turning it into an open system too under some circumstances. So what type of system is this, exactly?
    I see open tanks in process settings. Large tank, open to atmosphere with the city makeup plumbed to it with a float, or electronic level control.

    I’ve been corrected before in my descriptions of expansion tanks. I usually call a non bladder expansion tank (open) which is incorrect. Open systems are open to atmosphere. Regardless an expansion tank should be valved out for filling a system.

    An open tank (to atmosphere) is apparently what the OP has.

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