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Problem After Bypass Circulator Pump Replacement

pk232
pk232 Member Posts: 6
I have a Weil-McLain GV-4 series 3 boiler where the bypass circulator failed leaking current to ground tripping the breaker.   I replaced the circulator and cured the breaker problem but now the pipes on the “From System” side seem to heat up first when heating the domestic hot water and it does not circulate through the zones at all even when the boiler is up to temperature.  Unfortunately I did not note the flow direction before I took the old pump out but would have thought it would create flow in the same direction through the boiler as the regular circulator so I installed it so that flow is away from the inlet/outlet side of the boiler.   After I noted the problem I checked the old circulator and if the side that has the most rust on it is the bottom, then I installed it correctly.  It also seems to be that both pumps are oriented the same based on the drawings in the manual.   Lastly once the boiler is up to temperature I would expect the bypass pump to be off and not have any effect regardless of orientation.  I did not remove the system circulator so I know that is oriented correctly.  



One question is, is the pump oriented correctly or have I made too many false assumptions? 



The second question is, what else might be the problem if the pumps are oriented correctly?  I would have thought if there was air in the system it would have moved to the high point but a check of several bleeder valves only vents water.





 





  

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Pump direction critical...

    Look at the old Taco pump you removed. There is an arrow cast into the volute of the pump showing direction of flow. Match that. Motor orientation does not dictate direction of flow. The motor can be mounted in 4 different directions, and only one is correct.



    Also, there is a thermostatic valve (anti condensing valve) that can and will fail, causing hot water availability issues. The boiler makes it, but due to the closed valve, it can't be extracted.



    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.
  • pk232
    pk232 Member Posts: 6
    edited July 2012
    re: Pump direction critical...

    That was a good thought and it  would have worked if the motor was still attached to the housing, but it isn't.   As a result there is no way to determine the flow, except as I originally described which is not conclusive.  I was hoping somebody that was familiar with the Series 3 would know for sure.  Actually, I suspect that anybody who routinely works on boilers with a bypass circulator in that parallel arrangement  with the system circulator might know  which way the flow should be, and might even be able to suggest what else the problem might be if the circulator is mounted correctly.



    As to the thermostatic mixing valve, I do not think there is one.  I believe the amount of mixing is controlled by a water temperature switch that controls the bypass circulator for mixing.



    Thanks for your thoughts.
  • RobG
    RobG Member Posts: 1,850
    Pump Orietation

    Both the return pump and the bypass pump should be flowing from left to right as you are facing the boiler.

    Rob 
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    No thermostatic valve...

    Now THAT IS news to me. Went on line, brought up their I,O&M manual, and by gully, you sir are correct. No more thermostatic valve...



    Sorry for the misdirection.



    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.
  • pk232
    pk232 Member Posts: 6
    Problem Solved

    Thanks for the confirmation and taking the time to reply.



     While waiting for a response I decided to study the situation a bit more and after thinking about how the water flowed it occurred to me if the system circulator was not working, then perhaps the bypass circulator would pump the water backwards.   As I had disconnected each circulator in turn to determine which one was creating the electrical fault, my first thought was perhaps I had done something wrong when I hooked the wires back up and that could be the problem.  As a result I removed the cover over the wires on the system circulator and checked the wiring.  At first blush all looked fine but when I removed the wire nuts to make sure the wires were joined together well, I noticed the line side connection looked heavily oxidized.  Not wanting to physically shorten the wires, I cleaned both wires as best I could, put some Deoxit on them, and redid the wire nut.  I then did the same on the neutral side for good measure even though those wires did not look as bad.   After I turned the boiler back on I noted that based on the temperature of the pipes going to and from the hot water

    heater, the flow was now as expected.  I then tried one of the heating zones and circulation was fine there as well. 



    The good news, if you can call it that, is that if ever I see those symptoms again, I

    will know enough to first look at the system circulator as the possible bad actor.



    Thanks to all who took the time read my posting and give it some thought.

     
  • pk232
    pk232 Member Posts: 6
    Not A Problem

    Thanks for taking the time to reply
  • Paul48
    Paul48 Member Posts: 4,470
    The

    flow should be opposite the direction of the circulator you didn't touch. You have 2 connections at the boiler, supply and return. There is never a condition where you would want both circulators pumping at the boiler, or both at the system.
  • pk232
    pk232 Member Posts: 6
    Re: The

    If I am reading what you typed correctly, you are saying the opposite of what RobG said, and to be honest, it doesn't seem to make sense.   I would think if I hooked it up as I think you are stating, there would not be much water going through the boiler.   While trying to determine why things were not working I studied the water flow and  I think if  hooked it up as I believe you are saying, the system circulator will simply feed the bypass circulator which in turn would simply push the water out of the boiler to the system since the system circulator is drawing water from from the system into the boiler.   What am I missing? 
  • RobG
    RobG Member Posts: 1,850
    pk232

    You are correct, the bypass circ is pulling off the supply and pumping into the return thereby increasing the return water temp to prevent condensing. I'm not sure how the bypass circ is controlled, but that is the principal.

    Rob
  • Paul48
    Paul48 Member Posts: 4,470
    Sorry

    You're not missing anything, I was. The connection at the supply tapping for the bypass. In all the drawings in the I&O manual, it looks like a straight connection, bypass pump to system supply.
  • pk232
    pk232 Member Posts: 6
    Thanks for Letting Me Know

    I wasn't about to change what I did since I am a firm believer in "not fixing what isn't broke" but I am not an expert so this last posting makes me feel a lot better.  Thanks for taking the time to let me know.

     
This discussion has been closed.