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hot water baseboard pump

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mike212
mike212 Member Posts: 50
I have a steam boiler (oil) that supports a small hot water baseboard zone. The zone is in the basement which remains warmer than the rest of the house so the zone is often left off. When I do turn on that heat, the water pumps through the system but then the pump seems to turn off after a while. Sometimes it does turn off appropriately - when the thermostat hits the proper temperature - but often the water just stops pumping even if the thermostat hasn't hit temperature. Water pumping tends to last between 15 and 60 minutes before it stops. I don't it ever lasts longer than that.

When this happens, I need to do the following to reset it, otherwise it just never seems to restart. Turn off the heat via the thermostat (or lower the temperature enough such that there is no longer a call for heat). Then wait at least 5 minutes, often need to wait 15 minutes or longer. Then turn heat back on via thermostat. The pump then starts up again.

We've been in the house for a year and it's always acted this way. I do believe that the thermostat is not the issue since I changed that out and the issue remains. Is there likely an issue with the pump or some troubleshooting I can do to isolate the issue?

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  • Leon82
    Leon82 Member Posts: 684
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    Thermal trip possibly?
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
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    Sounds like the pump is going off on thermal. Could be that it's not rated for the water temps from a steamer or it could be failing bearings. It could also be low voltage or a bad power connection causing low voltage.

    That's where I would start.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,624
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    Carefully.......... put your hand on the pump motor after it's been running a while and see how hot it is. Warm is ok.... you should be able to hold your hand on it.
  • JUGHNE
    JUGHNE Member Posts: 11,076
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    Is it a 3 piece pump, that is motor connected to pump with a coupling module in between.......or a small softball sized self contained pump? Picture would be good.
  • lchmb
    lchmb Member Posts: 2,997
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    is the steam system calling on and an aquastat opening to protect the circulator?
  • mike212
    mike212 Member Posts: 50
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    The photos attached from a close zoom on the pump label to a wide view. Working on answers to all your questions/ideas. Will follow up.
  • mike212
    mike212 Member Posts: 50
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    @EBEBRATT-Ed I used an infrared thermometer to check the temps - was afraid to keep my hand there long. Temps on most of the circulator were 180 to 190. The box portion that doesn't seem to contact the water was cool, under 100. I attached a photo where I labeled the temperatures on different portions.

    My aquastat was set to 180 so those temps are in line with the aquastat setting.

    @lchmb This happens whether or not the steam system is calling. It looks like the circulator is rated up to 240 water temp. Water boils at 212 so does that mean it can handle pumping even when the main system is calling for steam?

    @JUGHNE I believe its a 3 piece pump. I attached some pictures in the post just before this one.

    @Leon82 and @Harvey Ramer There may be a correlation between the temperature of the water to how long the circulator will run. My poor memory now thinks there is a relationship, but I'll pay more attention to that now and see if I can isolate that as a cause. I'm not sure how to test for a possible low voltage issue.

    Something to note. When the this does happen and the circulator stops running I must turn the heat off from the thermostat (or lower the temp so there is no call for heat) and then wait at least 5 but usually more like 15 minutes. Now this wait time is necessary even if the circulator stopped an hour ago.

    Thanks for all your thoughts on this, I hope to figure it out.


  • Leon82
    Leon82 Member Posts: 684
    edited November 2017
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    That's a taco 007. Pretty common. It's an f4 and I think f 5 is the newest rev before you get to ecm model. It's 3 pieces, but not the type that was suggested earlier

    If it is getting heat soaked over time it may cause it to stop, but I'm not sure .
    Do you have a multi meter? You can pull the sheet metal cover off and check for voltage at the pump when it stops
  • mike212
    mike212 Member Posts: 50
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    I don't have a multi meter but can probably borrow one this week. If there is voltage when the pump stops does that indicate the pump needs to be replaced?

    I tested setting the aquastat to 150 and made sure the main heat doesn't call for steam from the boiler. That temperature water allows the circulator to run long, hour+ without stopping while still heating the room. Set to 180, the circulator ends up stopping within 10 to 30 minutes. When the boiler is producing steam, the circulator runs for less then 10 minutes.

    It seems like setting the aquastat to 150 may be the solution.
  • lchmb
    lchmb Member Posts: 2,997
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    I would test for power at the circulator when it stops running. Setting the aquastat to 150 only works when the rest of the house isnt trying to heat. It almost sounds like it cant take higher temps and needs to be replaced..
  • mikeg2015
    mikeg2015 Member Posts: 1,194
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    If you don't need water that hot (sounds like you don't), then maybe consider adding a bypass to drop supply temps. This also prevents the risk of flash steam. It's the recommended way to pipe a hot water loop off a steam boiler.