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    Boiler not circulating water

    Asked Mar 18, 2009, 08:34 AM — 12 Answers
    I have a question that I believe (and hope) is related to the filling of the boiler rather than a mechanical problem with the circulator itself.

    Since draining/refilling the hot water boiler, the heated water has not been traveling to all pipes. Some pipes are extremely hot and others are ice cold. I have been trying things under the assumption that there is air stuck in the pipes, as the circulator pump is running... but I am having trouble bleeding the system completely.

    There are no relief valves in the baseboards, and I have attached a drawing of where the only valves accessible are. Is there are specific set of steps I am missing in order to get the water traveling completely around the system?

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    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 434
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    #2

    Mar 18, 2009, 09:34 AM


    What is the elevation? One story or two?

    What is the pressure gauge reading?
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    bauer09's Avatar
    bauer09 Posts: 94, Reputation: 4
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    #3

    Mar 18, 2009, 09:56 AM
    It is a duplex - so the boiler is in the basement but the baseboard heaters are on the 2nd floor. The pressure gauge is between 10 - 20 psi... which is the range it has been in when functioning correctly in the past.
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    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 434
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    #4

    Mar 18, 2009, 11:10 AM


    Hopefully you can find a high bleeder or you will have to pressure bleed the system. If pressure bleeding is necessary I suggest you call for help from a ON Site professional since that can get you in trouble real fast.

    Are you sure the circulator is pumping water?
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    bauer09's Avatar
    bauer09 Posts: 94, Reputation: 4
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    #5

    Mar 19, 2009, 06:53 AM
    Found the answer and fixed it -- thought I would update just in case anyone else has a similar problem.

    There was air in the system, but what I was missing was two more valves on the return lines that are just downstream of the outlet valves on my drawing. These valves needed to be shut so that the air/water could not keep traveling through the system. After closing these, bleeding the air out of the outlet valves, and then reopening them, the system is back up and running.
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    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 434
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    #6

    Mar 19, 2009, 09:15 AM


    Without finding those you would have to call for professional service to add the valves or if you are capable you would have to add them yourself. That is what pressure bleeding is all about. In order for the system to be complete there still should be one air vent. It can be auotmatic or manual. This vent might be on top of a bladder type tank but not on a nonbladder tank system. As water heats up it will release more oxygen/air into the system. The purpose of the one auto or manual valve it to release the additional air after it is released from the system by the heat of the water. Glad you got it going.
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    Apachie58PU's Avatar
    Apachie58PU Posts: 4, Reputation: 1
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    #7

    Mar 19, 2009, 11:17 AM
    Quote Originally Posted by bauer09 View Post
    I have a question that I believe (and hope) is related to the filling of the boiler rather than a mechanical problem with the circulator itself.

    Since draining/refilling the hot water boiler, the heated water has not been traveling to all pipes. Some pipes are extremely hot and others are ice cold. I have been trying things under the assumption that there is air stuck in the pipes, as the circulator pump is running...but I am having trouble bleeding the system completely.

    There are no relief valves in the baseboards, and I have attached a drawing of where the only valves accessible are. Is there are specific set of steps I am missing in order to get the water traveling completely around the system?
    Shut off Boiler Turn off valve to expansion tank open drains to expansion tank and small opening to air intake ,could take 1/2 to 3/4 hr to drain LEAVE OFF and shut all ports
    Then shut off all three valves, there should be a drain valve between those 3 valves hook a garden hose to it then open 1 line valve and let water run till the air stops the boiler fill valve should push the water and air out. Then shut off that valve and repeat the process you can tell by sound when there is no more air. Then shut off the spigot and disconnect the garden hose and open all 3 valves. Start firing the boiler and watch the pressure gauge carefully when it gets near 30 lbs open the valve to the expansion tank quickly then just leave on the boiler switch and you should be OK Semper Fi Paul
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    Apachie58PU's Avatar
    Apachie58PU Posts: 4, Reputation: 1
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    #8

    Mar 19, 2009, 11:34 AM
    Quote Originally Posted by bauer09 View Post
    I have a question that I believe (and hope) is related to the filling of the boiler rather than a mechanical problem with the circulator itself.

    Since draining/refilling the hot water boiler, the heated water has not been traveling to all pipes. Some pipes are extremely hot and others are ice cold. I have been trying things under the assumption that there is air stuck in the pipes, as the circulator pump is running...but I am having trouble bleeding the system completely.

    There are no relief valves in the baseboards, and I have attached a drawing of where the only valves accessible are. Is there are specific set of steps I am missing in order to get the water traveling completely around the system?
    looking at the drawning again you need to find a spigot on the outlet line the fill valve will push the water through the open return valve and through that line back to the boiler you definitely have an air problem with a 2 story building there may be bleeders in the attic that is where your expansion tank should be there also ignore the instruction for the expansion tank if you have an X trol tank that would look like a small tank hooked to the return tank> you have to bleed one line at time for this to work I was a Union Pipefitter servicefitter for a lot of years Semper Fi Paul
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    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 434
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    #9

    Mar 19, 2009, 11:40 AM
    He already has it working. Read his last post.
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    2cruze's Avatar
    2cruze Posts: 2, Reputation: 1
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    #10

    Dec 29, 2013, 12:44 PM
    My boiler has the same problem…hot water travels to 3 zones but one stays cold….I replaced the thermostat and also the zone valve…still nothing…I tried purging the air out through the spigot and got a few bubbles but still nothing….I drained the system completely and refilled and now other zones have almost the same problem….This system has only one spigot and one relief valve…I believe there is a lot of air in the system and I just can't get it out…I wish each zone has a separate spigot so I could drain then one at a time…

    Any suggestions? Thanks
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