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  1. #1
    Join Date
    Jul 2003
    Posts
    5
    Here is the situation. Went on a call yesterday. Homeowner complained when the furnace came on it exploded real loud. He is absolutely right. On a call for heat. valve opens up, you can hear gas flow, but wont light. After a very length of time, it ignites and blows fire out the front sometimes two feet. which knocks out the pilot. Changed the valve, pulled the orfices and burners and wire brushed them and blew them out with air. Pilot is good and strong.
    My question, do the burners have to place back in a sequence. I didnt think so cause i have cleaned several and never put them back in any certain way. NOte, that this furnace has been leaking water for quite a while cause the a coil drain line was clogged. water in the base of the furnace in the blower compartment. The burner chambers have evidence of heavy rust. Thought maybe heat exchanger rusted through but didnt think that would cause it not to light. Never run into this problem. Maybe some of you with more experience have and can give some advice on what the problem might be. Incidnetly, a couple of times it did light, one time only one burner lite and the other time three out of four lite.

  2. #2
    Join Date
    Jul 2005
    Posts
    947
    The problem? 23 year old furnace with little or no maintenance, that's what... Heavy rust in the HX? Water through the furnace? You replaced parts on that POS? Cost vs. benefit, think about it.

  3. #3
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,793
    LOL, some times you should talk to the ho about replacement, before you try to fix the unit, this was one of those times.

    Did you check the manifold pressure.

    Did you blow out the manifold.

    Does your company have enough margin on swap outs to discount the service call if they change out the furnace.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,038
    You may have a burner cross over restricted. Reclean burners and pay attention to the carry over slots.

    But first, as said above, talk to HO about a new furnace. There are dimples in the heat exchanger that rust out. It's hard to find without a water test.
    Beware of advice given by some guy on the Internet.

  5. #5
    Join Date
    Oct 2005
    Posts
    69
    Generally most servicemen try to put the burners back in their original slot, but it is not mandatory. When you buy new burners they are not numbered 1,2,3,4 etc. However that explosion you described is a updraft blockage most likely caused by the rust. High gas pressure and blocked tubes contribute to the problem. Be careful of what you are doing. If it happens again for any reason and a mishap occurs the liability goes to the last person who worked on the equipment.

  6. #6
    Join Date
    Feb 2004
    Location
    Central Kansas
    Posts
    1,145
    In addition to cleaning burners and cross tubes, make sure you have positive draft flow. Had an LPG furnace once that lit with a serious bang. Discovered it was experiencing a slight downdraft due to a damaged vent cap and vent piping too close to roof line. Corrected draft problems and lighting smoothed out, but also I cleared a lot of lint from the burners and cross over tubes. If a little lint can disturb proper ignition, just imagine how a bunch of rust particles can do the same or worse.

  7. #7
    Join Date
    May 2005
    Posts
    996
    i had a furnace blow up in my face in vocational school i was standing off to the side as i was taught to do with a 'strange' furnace. scared the crap outta me. and i never went near it again except with the temptation of getting a hammer and saying 'things' of a strong nature under my breath every time i looked at it!

    now,if a furnace blew up on me again, i would condemm the pos faster than the homeowner could run down to the furnace to see whats going on!

  8. #8
    Join Date
    Apr 2005
    Posts
    333
    Sounds like a lot of time and money going into a LIABILITY
    meanwhile, back at the ranch.....

  9. #9
    Join Date
    May 2005
    Posts
    996
    it is 23 years old and i wouldnt trust the thing with a dime in the first place, so why would you trust it with your life. oh yes home owner! it does have some control over your fate this winter as you sleep in your nice warm bed at night thinking how nice it is to have heat. next thing you know beep beep beep goes the co alarm and then bang! fire alarm goes off 30 seconds later! KILL THAT CARRIER AFORE IT KILLS YOU!


    you have been warned!

  10. #10
    Join Date
    Jun 2003
    Location
    Jacksonville, FL.
    Posts
    4,313
    Originally posted by gandl
    After a very length of time, it ignites and blows fire out the front sometimes two feet.
    And how did you get this measurement?
    WHY?

  11. #11
    Join Date
    May 2005
    Posts
    996
    he measured how far up his arm the hair had disappeared.

  12. #12
    Join Date
    Jun 2003
    Location
    Jacksonville, FL.
    Posts
    4,313
    LOL!!
    WHY?

  13. #13
    Join Date
    Mar 2003
    Posts
    293
    did you check the hx for cracks.
    Thats the first thing i do on any system 20+. i don't even look into their problem until I've made sure that HX isn't compromised.

    Acrtually thats a lie the other day i went on a clean and check and cleaned it first. It looked like it was burning good. the HX looked clean but it was 30 years old. so i pulled the blower to oil the motor and then i did a water penetration test. The water rained down like a waterfall. Hell if i had done that first i would of been out of there in 20 minutes.

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