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Lochinvar nobel set point met inappropriately?

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mattvan123
mattvan123 Member Posts: 3
in Radiant Heating
I have a lochinvar noble combi boiler. It is two years old. Has worked very well.

The heat is baseboard, and we recently had to fix a small leak in the baseboard (possibly due to someone bumping it hard), which required draining a zone. Since fixing that leak, about once a day the system stops emitting heat and says "set point met." Circulator pump still running but no heat is in the pipes and it stays at "set point met" indefinitely. It somehow seems to think the set point is met when it has not fired up for over an hour and the radiators and outlet pipes are cold.

If I run DHW for a minute or so and then turn off the DHW faucet, the boiler kicks back on. I think there must be air in the lines or something causing the unit to think the set point is met because the water cannot flow? Any other possible causes.

Thanks.

Comments

  • Zman
    Zman Member Posts: 7,569
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    It sounds like an air lock.
    If you post some pictures (standing back so we can see the whole system), we may be able to help.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • mattvan123
    mattvan123 Member Posts: 3
    edited January 2021
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    Heres one. Two baseboard loops with individual grundfis circulator pumps.  Worked fine for over a year and only had this problem after the draining of zones.  So I am assuming air lock.  The c
  • Zman
    Zman Member Posts: 7,569
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    It looks like the 2 purge valves on the right side of the picture are going to be the best purge points. If you connect a hose to the fitting with a the cap, then close the thin metal handle on the outside and open the little solid handle, you should be able to purge the air. Do them one at a time and let it run until you get a steady stream of water with no air burps.

    You may be able to power purge by overriding the pressure reducing valve located just off the bottom right corner of the boiler. I am not familiar with that model, it is the part that has a dark blue or black cap. If you post a close up of that part I am sure someone here know what brand it is.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • brianbuy
    brianbuy Member Posts: 3
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    I'm having the same issue with this, so is there air pockets? It just suddenly stopped heating up the pipes. I do get Domestic Hot Water for the shower but heat seemed to have stopped working for a few days now.
  • hot_rod
    hot_rod Member Posts: 22,158
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    Your system is piped with really good purge valves and locations. Do one circuit at a time, until the water runs a solid stream, it can take 10, 20 minutes or more, depending on loops, lengths, etc.

    Hook a 5' wash machine hose on the purge port and stick the end in a 5 gallon bucket to better see when the small air stops purging out.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Daveinscranton
  • brianbuy
    brianbuy Member Posts: 3
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    I think it's a software issue because I am able to put it into service mode and it runs and heats. I ran the setup wizard again and reset the settings to the original. So far it's running and heating but we'll see if the "Set Point Met" comes up again later.
  • brianbuy
    brianbuy Member Posts: 3
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    So the technician finally figured it out. The plumbing was loose and dripping water on a sensor inside the boiler. The sensor which was tripping the "Set Point" was corroded and needed to be replaced. They are coming in to change it but that seems to have fixed the ongoing issue by wiggling the sensor, I attached the picture.

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