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  1. #1
    bradlack Guest
    Ruud 90+
    15 years old

    Went to start furnace for the first time of the season. It would not ignite and I tried several times. Controls, purge cycles,hot surface igniter, gas valve all seem to follow normal sequence. Inductor fan output great all limits test ok.

    Robertshaw 7200 DER SO 3. I broke the pilot output of the valve and there is gas coming out at the appropriate time in the ignition cyle. But there was no flame. Assume the pilot which feeds the crossover was plugged at the oriface or elsewhere. So I opened up the burner compartment and discovered that 2 of the ribbon burners are partially corroded out - Couple of 1-2" gaps in each. The tube at the igniter is fine.

    I have new burner on order but I'm second guessing that decision. Its about 2 weeks out and it is getting cold at night so I made a temp repair to the burner. Won't go into details but I have plugged the gaps in the ribbon and provided roughly equivalent opening to the ribbon.

    Cleaned the rest of the burner and reinstalled. Still no ignition, well at least not all the time. It will go through the cycle and not light and then on the second or third try it will light. My repair burns perfectly with a nice even blue flame over the entire burner. I'm starting to worry that maybe it is not solely a burner issue and that I may have a gas valve issue. With the cost of the burner and a gas valve I'm into a reality check if I should just bite the bullet and replace the furnace. Its a lot of money right before Christmas. HO HO Humbug.

    I neglected to clean the main orifaces during my rush to try out the fix. Any body ever experience these symptoms. Could burner open area and/or a partially restricted oriface cause the mis fire or is this more likely a gas valve issue??

  2. #2
    Welcome to HVAC TALK. However this site has rules against giving out technical advice to DIY'ers. I have attached a link below for your convenience.

    Here's something to think about though...

    When was the last time you had that unit cleaned and inspected?

    Now you have a problem with the unit. Fuel costs are skyrocketing.

    So why not call in a professional to repair the unit? While they are there they can clean and inspect your unit to insure a safe living environment for you and your loved ones. Not to mention, having an efficient running system could save you more than the cost of the service.

    What's your safety worth? I'm guessing more than the repair bill.

    Thanks for your understanding.

    (we can't help DIY, due to site rules )

  3. #3
    Join Date
    Oct 2002
    Posts
    369
    Originally posted by jultzya
    Welcome to HVAC TALK. However this site has rules against giving out technical advice to DIY'ers. I have attached a link below for your convenience.

    Here's something to think about though...

    When was the last time you had that unit cleaned and inspected?

    Now you have a problem with the unit. Fuel costs are skyrocketing.

    So why not call in a professional to repair the unit? While they are there they can clean and inspect your unit to insure a safe living environment for you and your loved ones. Not to mention, having an efficient running system could save you more than the cost of the service.

    What's your safety worth? I'm guessing more than the repair bill.

    Thanks for your understanding.

    (we can't help DIY, due to site rules )

    Amen to that whole post...Have alredy seen three house fires on the news this year due to DIY on fossil fuel furnaces and it's only November....I would only add this...If your really interested about how this stuff works...then watch the technician..I know, I don't care if you watch...heck, I encourage it.
    But for your saftey and property,the only sensible thing to do is call a PRO.
    Havin'a good time is what life is all about.

  4. #4
    bradlack Guest
    Well as I read the posts about landlord issues and the like. It certainly did not look like a closed discussion group to DIYer's. You have a professional page so it is logical to assume that the public section is open to everyone.

    I'm a professional engineer designing gas safety circuits for large gas turbine projects. I understand very well the theory of the protections and controls but I'm just not familiar with gas physics at a couple inches of pressure. When I see things in 100's of PSI it just works different and I thought I was soliciting an opinion not anything that would incur a liability.

    I clean my furnace completely generally every other year. That is complete fan out, burners out etc. Obviously filters get a more frequent change. The burner corrosion has been gradual over the years it just went critical this time. I'm just concerned that I may be faced with two problems due to the intermittent nature.

    Generally I don't see the need to trust my families safety to anyone else especially when I read the wall of shame articles posted here. Many I'm sure done by the "professional" ticketed guys who once cleaned furnaces until they became installers.


  5. #5
    Join Date
    Nov 2001
    Posts
    1,874
    Originally posted by bradlack


    I'm a professional engineer

    Not what anyone here wants to hear, sorry
    If you try to fail, and succeed.
    Which have you done ?



  6. #6
    The forum is open to the general public for discussing general information.

    When it comes to technical questions we like to leave this part to the professionals that come in contact with equipment like yours... EVERY day.

    I understand that you have training and experience on a larger, different scale... but why not leave the other areas to the professionals that know the ones you are not so familiar with?

  7. #7
    bradlack Guest
    I guess that I learned something about honesty tonight. Next time I ask something I will have pretend to be a HVAC contractor and couch my question in what would you have done type language.

    I would appreciate if the moderators could strick my name off HVAC Talk.com. It is of little use to me to be a member.


  8. #8
    Join Date
    May 2004
    Posts
    12,259

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