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  1. #1
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    Jul 2016
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    Combustion blower fault

    Hello everyone this is my first post here. I am hoping someone could give me some advice on troubleshooting a heating system.

    We had a bad storm and lost power, when the power returned we didn't have any hot water. I saw the relay board LED was out and it had 120VAC coming to it. I tracked it back to the transformer that steps down and isolates the line voltage to 24vac. I had a variac so I hooked it up and set it at 24VAC, the board lights so everything seems fine with that I just need a new transformer. Here is where I am having a problem. I have an IBC DC series Combi Boiler and I am getting a fault code of "8" on the main display which indicates "incorrect fan speed", possible causes are listed as; Fan rubbing on casing, wiring between fan and casing, check wiring for poor wire contact, replace fan, replace controller. Now since this happened after the storm I am thinking it's a bad controller or fan motor maybe? I am getting 120VAC to the fan power connector. There is a control connector that has four wires which I read 16VDC and 4.2VDC. I did notice a somewhat charred NTC thermistor that blackened a film cap it was next to. Now I don't know if that thermistor is being used as a current limiter or a temp sensor, I measure 6 ohms across the thermistor at ambient room temp. The markings on the NTC thermistor are "NTC 5,0" and "1108", I can't find anything about it in any datasheets. The blower motor is a "Torin-Sifan" DSB144-22 077936-01. It's easy to see the PCB traces on the front side but I can't see the back side so tracing things is a pain in the butt. If someone can explain how these are controlled that would be great, I am guessing PWM? I have a variac and oscilloscope along with multimeters etc.... I build audio amplifiers so I know my way around amps not boilers lol

    I am heading down there now to take some photos to post, maybe they can help you guys help me.

    Thanks in advance.

  2. #2
    Join Date
    Jul 2016
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    Thread Starter
    To be more specific on the model of the boiler it's an IBC DC 33-124

    There is a 15A/250v through hole fuse I want to test but the traces are on the back side of the board, Can I just remove the mounting bushing fasteners for testing?

    I have a picture but I can't post because I need 7 posts. Can I bump this thread 7 times in order to upload the image? I don't want to go against the rules, maybe I can PM someone the link to the image if they are interested in helping.

  3. #3
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    Jul 2016
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    Thread Starter
    bump

  4. #4
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    Jul 2016
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    Thread Starter
    I am assuming since I can't find any info on the NTC thermistor that the "5.0" means it's value of resistance at 25C is 5R, me measuring 6R makes sense with test leads resistance summed. Maybe the the proximity to the film cap caused the blackening, it was touching it, probably not good for the cap.

    I think I might try and pop that board off so I can test the 15A fuse, I can't get any continuity through the blower motor at the connector and when I trace where it goes to on the PCB it appears to go to the fuse. Do you HVAC techs actually get down to component level and replace things like the through hole fuse? The guys I know around here just replace the whole board. To me it seems like a waste, that blower is like $!!
    Last edited by beenthere; 07-25-2016 at 04:12 AM.

  5. #5
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    We cant help with DIY on this site

  6. #6
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    Jul 2016
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    Thread Starter
    Well I should have read that before posting.

    I never feel threatened to share my information, I guess not everyone feels the same. This is why I don't hire anyone in the industry, I will join a diy site where people will actually help me do it myself.

  7. #7
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    Jul 2016
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    Thread Starter
    I didn't know this was a cash grab site.


    Mods feel free to delete my account and delete this useless thread.

    Thanks.

  8. #8
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    It's not me, or anyone else on this site, being threatened by giving knowledge. It's the site rules, and the agreement the professionals signed to when they were vetted by the site admin.

  9. #9
    Join Date
    Jan 2004
    Location
    PA
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    Sorry we're unable to help you.

    Thread closed.
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