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Can someone help me with this?

Discussion in 'Permanent Threads' started by sublime, Oct 20, 2009.

  1. Nettdata

    Nettdata
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    Stupid question... but are you putting the filter in the correct way? They have a definite airflow direction, and if you get it backwards, it can really impede airflow.

    Also, are your airflow settings on the controller in the factory default mode? They are usually a set of dip switches. If they weren't properly configured by taking static pressure measurements of your system, it might have the improper ramp-up settings that would cause it to trip.

    So if your furnace guy just came out and installed it without doing any measurements, then it might not be properly tuned for your duct flow.
     
  2. zzr

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    I'd start by checking your blower fan. It may be loose on the motor shaft or the hub may be cracked. That would allow it to work sometimes, but if it's slipping then there won't be enough airflow and it would likely make a noise from the vibration.
     
  3. Nettdata

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    Good call.

    I automatically assumed that the blower would be attached with a key of some sort, which wouldn't let it slip like that.
     
  4. Whatthe...

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    First thing I checked was the filter direction. In my typical paranoia, more than once actually. It's in the correct way.

    I'll check the dip switches too, but the furnace is 5 years old and this is the first time it's made noise.

    I'll check this as well. The vibration happens when the draft inducer fan starts up. The vibration stops before the blower fan kicks on. It's just a little 6 or 8" housing, I wouldn't have thought that fan has enough rotating mass to vibrate the ducting like it has been.

    Thanks for the help!
     
  5. Nettdata

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    You might have something like a mouse in the blower fan that might be causing it to vibrate as well... just because it's slightly out of balance.
     
  6. Whatthe...

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    Me thinks I found the problem.....

    Plugged Vent.JPG

    HRV intake vent was almost completely blinded off. I cleaned off the vent and haven't heard the vibration yet. I'll keep an eye on it to make sure.

    It's a variable speed furnace so I figure when low fire heat was called there was enough air available that the furnace would start, but if high fire was called the HRV couldn't supply enough fresh air into the house, creating the vibration on startup and the furnace reverted to low fire mode and threw the error code.
     
  7. Nettdata

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    Ha. I think you may be right.

    Funny how a quick visual inspection really sheds some light on things.

    I always found it funny when people would be driving and then feel/hear something, but never actually look to see what it might be... and then as soon as they did look, it was blatantly obvious what the issue was.
     
  8. Whatthe...

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    Totally. I'm super glad I didn't just blindly follow the service tech's recommendation and order a new inducer fan and blower fan. I'm 99% certain that intake vent was the problem.
     
  9. Nettdata

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    Says a lot that the "pro" didn't figure that out.
     
  10. zzr

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    The draft inducer fan could be doing the same thing. I had the same problem on our tankless water heater, which has a variable speed forced induction fan. It vibrated for a while then finally stopped working when it came off the shaft.
    Lots of "pros" are like that - keep replacing parts until it works again. Most people don't know any better, so the cycle continues.
     
  11. Whatthe...

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    I'm super irritated with the "pro" that came out. If he had taken a few measurements on how the unit was firing he probably could've found the problem pretty easily. I've since gone through the installation manual for the furnace and I'm pretty sure if he had measured the differential pressure developed across the blower fan it would have shown that there was a restriction in the supply ducting.

    I wrote him off as being an idiot when he told me I should turn off the HRV in the winter because it fights against the humidifier. I asked how is that possible when I have my humidistat set for 30% RH and the HRV dehumidistat set for 40%, so the humidifier maintains an RH of 30%, and if it gets above 40% then the HRV kicks into high speed and reduces the humidity. His response was: see they fight each other. Uh, yeah. Thanks for coming out, now leave please.
     
  12. Nettdata

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    I'd be tempted to call back the company that sent him out and bitch at them, assuming he wasn't an independent contractor.

    They might even throw you a few bucks to offset the stupidity.

    I doubt it, but it is Valentine's Day, so maybe the crusty old woman who answers the phone will have a soft spot for you today.