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  1. #1
    Join Date
    Dec 2004
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    Albuquerque, NM
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    Rooftop Fire - pictures inside

    This happened on one of the restaurants we service. The last PM was performed in May and they cancelled the last two that we had on our schedule.

    Looking at these photos I have a theory on what happened, but I want to hear other theories as well so Ill withhold mine for now.

    https://photos.app.goo.gl/Ufuk7eiL6vJnCDGq7
    Mark

  2. #2
    Join Date
    May 2014
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    Bay Area California
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    Photo #2 is pretty interesting. Also the burned disconnect.
    I do a triple evac with nitro to remove non condensables.

  3. #3
    Join Date
    Nov 2006
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    Southeastern Pa
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    Am I correct in thinking that the limit is an aftermarket part?
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
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  4. #4
    Join Date
    Jun 2000
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    WYO
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    Hmmm, refrigerant and oil leak, then flame from burners ignited it all when it called for heat ? Ive seen a couple bakelite compressor terminals blow and scatter oil like that, never seen the oil ignite tho.

  5. #5
    Join Date
    Oct 2011
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    Chicagoland Area
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    Quote Originally Posted by timebuilder View Post
    Am I correct in thinking that the limit is an aftermarket part?
    Looks like WR adjustable limit
    Officially, Down for the count

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  6. #6
    Join Date
    Mar 2010
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    Sunny SoCal
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    Hard to guess on the cause but easy to comment on the effect.

    Perhaps a natural gas leak/fire caused the fuse plug to melt releasing oil that then fed the flames & melted the condenser motor.
    Interesting that at least one of the blades retained its basic shape.
    I'm guessing that the oil then made its way to the roof causing the section of char.

    I'm not seeing any final gas line connection.
    Hard to believe that the line/fitting melted clean off.

    Kind of looks like the fire was sucked into the blower. Filter(s) weren't totally toasted so the flow of air/fire was an n the direction of supply air so guessing that the blower was running.
    Melted wires may have shorted out & killed the power.
    Eric

  7. #7
    Join Date
    Jun 2014
    Location
    Dover, DE
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    I had a very similar looking York Sunliner that burned a few years back. Didn’t torch the roof quite like that though.
    Someone had jumped the rollout, and it had a cracked heat exchanger. Rollout lit the insulation near the burner and that was all it took.
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

    Local 486 Instructor & Service Technician

  8. #8
    Join Date
    Dec 2004
    Location
    Albuquerque, NM
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    108
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    Thread Starter
    My theory is that the pounds to inches regulator failed and leaked gas out the vent which then got pulled into the combustion air inlet louvers igniting the gas.

    What I didnt think of but I do agree with is that the refrigerant oil was likely the fuel that contributed to the damage done.

    Now that Im typing this I wonder if an electrical fire could have ignited the oil.

    It appears that the threads on the aluminum combination gas valve gave and the nipple ended up pulling out of it causing a big gas leak.

    The fire department will have their repot available in a couple of days and Ill update my post.
    Mark

  9. #9
    Join Date
    Oct 2011
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    Chicagoland Area
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    Quote Originally Posted by rider77 View Post
    I had a very similar looking York Sunliner that burned a few years back. Didn’t torch the roof quite like that though.
    Someone had jumped the rollout, and it had a cracked heat exchanger. Rollout lit the insulation near the burner and that was all it took.
    Had a 5 ton Sunline unit melt a whole bunch of shit and commit suicide about 15 years ago. 3 wire limit welded shut on both contacts motor took a crap and she just cooked herself until the heat control circuit finally melted enough to kill the 24v. It looked like melted cheese.
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  10. #10
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    Dang, we're taking one of them off tomorrow

  11. #11
    Join Date
    Dec 2019
    Location
    Baton Rouge, Louisiana
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    That's a bad one. I had a call out on a brand new 10 ton daikin package system that was installed on the roof of a wing joint. It caught fire and the wanted a second opinion on why. I determined that having the return air 24 inches from an inadequately sized exhaust hood that didnt completely extend over the fryers, and the fact that the make up air was strapped to the exhaust blower on the roof was the problem. As soon as they fired up the furnace it ignited built up cooking oil inside the unit. I walked off that job because I didnt want to be in the middle of the inspector, fire marshal, or insurance company battle. It was the most dangerous ser up I have ever seen. Not even a disconnect.

  12. #12
    Join Date
    Jan 2010
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    I was lucky and caught this one in the act. I got to the roof and cycled the heat a few times to witness the controller open the gas valve and light it off. Only problem was it never started the inducer.
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