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HTP UFT80 foghorn noise

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Bob Bona_4
Bob Bona_4 Member Posts: 2,083
in THE MAIN WALL
All these years installing various brands and have avoided the dreaded foghorn. Right out of box, yesterday, it's my turn. LP. Also noticed on start, 3 fan bursts- ramp up, cut out, ramp up. Going back this am, to check out. Whatcha got, guys?

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  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited December 2016
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    Should be easy to fix the foghorn noise- also make sure your DIP switches are correctly set for LP and 2" or 3" venting.

    On my UFT-80 I do hear a 1 min pre-purge fan run then it ramps down, then the gas valve opens, then it ramps up again when firing.


  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
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    Thanks Rob, attacked it today, I needed to set the #4 dip for 2" venting. May have been the ramp problem. Enriched the burner mixture, previous was 46 ppm/9.5 CO2, now 64 ppm/11.7 CO2. Seems quiet.
  • NY_Rob
    NY_Rob Member Posts: 1,370
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    Glad you got it dialed in.
    It's a pretty nice economy mod-com.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    edited December 2016
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    I'm seeing that. Price point is good. 10:1 is frigging awesome. Hoping it's long haul stuff; not obsolete tomorrow! It replaces an 8 yr old Burnham Freedom with a holed HX. Took about 1.5 turns in to see a sweet spot, no way 1/8 like they say. Maybe NG responds differently. I missed that tidbit in the manual last night.
  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited December 2016
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    Mine runs on NG with 2" venting- the mixture setting was as good as it could get right from the factory.
    We tried fine tuning w/the combustion analyzer... but ended up back exactly at the factory setting for best results.
    On high fire I'm at 65PPM CO and 9.4% CO2
    On low fire I'm at 75PPM CO and 8.8% CO2
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
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    Interesting. Your final settings are what I started with. You can see the flame reducing 4-5x as its honking.
  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited December 2016
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    Wonder if it's related to the venting length?
    I have about 12' of 2" PVC total equivalent length if you combine the intake and exhaust runs.

    I spoke w/HTP support about venting before coming up with the placement of the boiler. IIRC they said 8' was the shortest EL allowed with 2" PVC for the UFT-80.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
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    Wow, and I'm at probably 30" with 2". Up 10" then thru wall. Makes me think of ductless ref piping min lengths. You're trained to keep things as short as possible then......
  • NY_Rob
    NY_Rob Member Posts: 1,370
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    Sounds like you've found the the possible culprit then.

    Originally, I was planning to locate the boiler on a different wall, but after contacting HTP I realized that was not possible as the venting would have been under 2' total length in that location.

    Mod-cons have a lot of unique venting requirements it seems.

  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
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    Seems so. No complaints so far. This minimum vent length spec, I'm going to look into next job.

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