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  1. #1

    Flooded Two Pipe Steam System

    A bypass valve on the feedwater line was opened by a janitor. The entire system flooded, two floors. We drained all the water we could at the boiler. Fired the boiler back up and began making steam. The problem is we are not getting hot through atleast half the building. The system was working fine before the flood. No cool spots and everyone was happy. What should be my next course of action? Haven't run into this problem before.

  2. #2
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    Have you verified that the air has been removed from the system. Steam will not travel down the line if air is in the system.

    Have you checked that air vents are working correctly. How about the steam traps.
    How many floors are in the building.
    What is the the steam pressure in the system.
    How large is the boiler or BTU rating.
    Is there a condensate pump in place and possibly a receiver.

  3. #3
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    Quote Originally Posted by jodaddy1956 View Post
    A bypass valve on the feedwater line was opened by a janitor. The entire system flooded, two floors. We drained all the water we could at the boiler. Fired the boiler back up and began making steam. The problem is we are not getting hot through atleast half the building. The system was working fine before the flood. No cool spots and everyone was happy. What should be my next course of action? Haven't run into this problem before.
    thats is very weird! cause the boiler water level is controlled by a float that turns on/off the feed water pump, opening the bypass valve would overflow the condensated receiver not the boiler.

  4. #4
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    Quote Originally Posted by valdelocc View Post
    thats is very weird! cause the boiler water level is controlled by a float that turns on/off the feed water pump, opening the bypass valve would overflow the condensated receiver not the boiler.
    I have seen where they have piped a bypass right to the boiler. Stupid but they are out there.


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  5. #5
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    Quote Originally Posted by qwerty hvac View Post
    I have seen where they have piped a bypass right to the boiler. Stupid but they are out there.


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    What kind of bypass you taking about? I'm taking about the make up water solenoid bypass, when the water level gets low in the receiver the float powers the solenoid valve allowing street water into the tank.
    I have never seen a commercial steam boiler with cold make up water piped directly into the boiler. next time you come across one please take a picture.

  6. #6
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    Quote Originally Posted by valdelocc View Post
    What kind of bypass you taking about? I'm taking about the make up water solenoid bypass, when the water level gets low in the receiver the float powers the solenoid valve allowing street water into the tank.
    I have never seen a commercial steam boiler with cold make up water piped directly into the boiler. next time you come across one please take a picture.
    I have seen a few where they pipe it right to the boiler with a valve. I figured it was to fast fill it after it has been drained. Normally I will see a bypass around the PRV. But these were piped after the PRV bypassing the condensate tank. I will take a pic of the on I am thinking about if I go there again. I can see if someone didn't know what valve they were opening filling the whole system.


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    Quote Originally Posted by qwerty hvac View Post
    I have seen a few where they pipe it right to the boiler with a valve. I figured it was to fast fill it after it has been drained. Normally I will see a bypass around the PRV. But these were piped after the PRV bypassing the condensate tank. I will take a pic of the on I am thinking about if I go there again. I can see if someone didn't know what valve they were opening filling the whole system.


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    That brings another question, why would a PRV be needed in a condensated receiver? I'm use to see PRV's with hot water boilers no with steam cause the water pressure is pretty much irrelevant.

    Also if the make up water was piped directly into the boiler, the street pressure 40lb to 80lb would had been higher than the 15LB opening pressure of the boilers relief valve, the whole scenario is flawed and weird, dont you think?

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    I've heard of some systems use pressure differential to lift water out heaters below the condensate line. if they're full of water, steam would not be able to clear lines of the water.

    water in rads/traps holding the thermostatic elements closed?
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  9. #9
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    I changed out a makeup water float assembly on a 50 gallon condensate receiver last friday. I believe it was a Hoffman. The tank nameplate said max inlet water pressure was 30 psi and a prv would need to be installed if water pressure was higher.
    Chaos equals cash$$$

  10. #10
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    Pretty much every commercial boiler I've come across in NYC has a city water feed piped directly to the boiler. The pipe with the green arrows is the city water feed.

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    Name:  ImageUploadedByTapatalk1356658404.442206.jpg
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Size:  40.6 KBName:  ImageUploadedByTapatalk1356658416.241167.jpg
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    Here is one that I was talking about. PRV on the makeup water.


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  12. #12
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    I see it all the time. When you drain a large boiler for inspection you can use the feed to refill the boiler on initial startup. Otherwise you will have to fill with your pump from the condensate receiver tank. On a 300-400 HP boiler that can take a while, I usually fill to the sight glass with the city water supply then valve it off and let the low water cut off fill the rest of the way with the condensate pump.

  13. #13
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    Quote Originally Posted by marylandtech View Post
    I see it all the time. When you drain a large boiler for inspection you can use the feed to refill the boiler on initial startup. Otherwise you will have to fill with your pump from the condensate receiver tank. On a 300-400 HP boiler that can take a while, I usually fill to the sight glass with the city water supply then valve it off and let the low water cut off fill the rest of the way with the condensate pump.
    No a common practice in my neck of the woods, typically the make up (street) water, goes through the filters,softener and to the condensate receiver. I wouldn't put raw,untreated water in,and wouldnt pipe it directly into the boiler for the obvious reason.

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