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  1. #27
    Join Date
    Apr 2007
    Location
    Tucson, Arizona
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    What brand, and model/serial is this furnace if any of those labels are legible? I have seen many brand new furnaces that have burner orifices capped from the factory. It’s not guaranteed that a technician changed the original design. Does your furnace have 1 motor only in it, to circulate the air in your home? Or is there another smaller motor towards the top that looks like part of the flue/chimney part? I’d guess your furnace is natural draft (only 1 motor) and could be as low as 60% efficiency. The minimum efficiency of current furnaces is 81%. Depending on your location/climate your contractor may recommend a high efficiency furnace up to 98%. A plastic smell could indicate a serious issue and should be investigated to resolution. Be very careful running your furnace. Please invest in a low level CO monitor.
    There are two ways to do things, Right and Again.

  2. #28
    Join Date
    May 2004
    Location
    Salt Lake City/Tooele
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    5,311
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    I am pretty sure we are dealing with a 3wire pilot and they do get flaky, but they usually always take some time to get warm enough to turn on the gas valve. It is when the gas valve/burners turn on and off or chatters that your looking at a failing 3 wire pilot assembly, so you probably paid out for something you did not need there. Newer techs find those earlier 3 wire pilot systems a curiosity and more often than not mis-diagnose them.
    Those older CES0110 carrier control boards with the ice-cube relays need a kick in the butt to get the blower relay to engage sometimes, but that only verifies it is time to replace the board due to the failing relay that the tech said he had to tap on to get working.
    SO I have a feeling that the board is failing, preventing the blower from operating properly or timely, two speed blower maybe and running at wrong speed, thus furnace overheating, getting nasty hot acrid smell. I have a feeling that dialing up the gas pressure is not going to make a huge difference in the temperature rise, but if the company did perform a true PM, they should have listed down the manufacture's listed "Temperature Rise" which is required to be listed on a furnace data plate/sticker by law. Then taken measurments of what the temperature rise is across the furnace versus what is listed and written down their findings. Temperature Rise is probably the number one thing any tech should take and record. This will dictate what the next step of the service visit will be. If the temperature rise is excessive or high, then I would be looking at static pressure, filters, AC coil, blower wheel, blower performance, gas pressure, etc.
    Right now it seems like a monkey poop fight and your not getting the specifics you need to make an educated decision on what to do and with your inability to supply us with that data, we are useless to assist you. All we can do is bicker amongst ourselves and utilize personal experience and opinions to blindly help you.

    Get us the model number of the furnace, does it have an AC coil?
    Get us the actual numbers from the service tech's visit, we need listed temperature rise, actual measured temperature rise, original gas pressure versus adjusted gas pressure setting. Blower listed amps versus actual running amps. Numbers don't lie.

    Good luck and Happy Thanksgiving

  3. #29
    Join Date
    Sep 2008
    Location
    VA
    Posts
    3,682
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    Quote Originally Posted by Olivero View Post

    You didn't have a problem until someone messed with it....
    Doubtful...

    Turning up the gp a couple 10ths of an inch didn’t create all of these issues.

    Did older “RGGED” furnaces work for years? Absolutely yes, but it’s very highly unlikely that a combustion analysis was performed. Remember this was back before the days of the electronic CA. We had a chemistry set in order to do it, and if your company performed this test routinely on any and all equipment modifications you’re one in a million.

    Just because “old school” modifications worked didn’t mean they were efficient and or safe. It just means they allowed the furnace to run. The longevity has nothing to do with the techs mods. It had to do with the durability of the equipment.

    When the introduction of redundant safety controls were adopted as a standard, techs could no longer perform these “old school” mods. Manufacturer specs became much tighter and there was less room for alterations. I’m sure cavemen were able to get really good fires going until they figured out it could kill them... Hmmmmm, I wonder why redundant safety controls were adopted as a standard?
    Last edited by mgenius33; 11-29-2019 at 10:29 AM.
    "The only true wisdom is in knowing you know nothing" Socrates

  4. #30
    Join Date
    Oct 2016
    Location
    Clearwater, Florida
    Posts
    1,546
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    Quote Originally Posted by mgenius33 View Post
    Doubtful...

    Turning up the gp a couple 10ths of an inch didn’t create all of these issues.

    Did older “RGGED” furnaces work for years? Absolutely yes, but it’s very highly unlikely that a combustion analysis was performed. Remember this was back before the days of the electronic CA. We had a chemistry set in order to do it, and if your company performed this test routinely on any and all equipment modifications you’re one in a million.

    Just because “old school” modifications worked didn’t mean they were efficient and or safe. It just means they allowed the furnace to run. The longevity has nothing to do with the techs mods. It had to do with the durability of the equipment.

    When the introduction of redundant safety controls were adopted as a standard, techs could no longer perform these “old school” mods. Manufacturer specs became much tighter and there was less room for alterations. I’m sure cavemen were able to get really good fires going until they figured out it could kill them... Hmmmmm, I wonder why redundant safety controls were adopted as a standard?
    Sure, but was it going off on overheat until someone messed with it? No.

    I'm sure any of us could walk in anywhere and find some problem with some unit, small or big, that's what we do.

  5. #31
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    10,055
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    I would doubt that turning up the gas pressure from 3.2 to 3.5 made a huge difference on temp rise. It is more likely that the furnace had air flow issues before this was done and the added gas just compounded the issue. I don't think the added gas pressure caused the smell or the board malfunction although it is a slight possibility. Since it was said that the heat run are buried under insulation I have to assume that the furnace is in a horizontal configuration. In this orientation it is possible for heat to travel into the blower/control section of the furnace while the blower is off and cause an overheating of the controls. This is usually caused by an obstruction to air flow like a dirty A/C coil mounted after the furnace which would also be a likely cause for the limit opening.

    The bottom line is you may not need a new furnace but it may be less expensive in the long run to cut your losses and change it rather than put more money into it only to find another problem later. If you should decide to have the unit replaced make sure that they do a load calc {Manual J} to properly size the new equipment. From the way you are talking it sounds like even with one burner inactive your furnace is still too big.

  6. #32
    Join Date
    Nov 2019
    Posts
    6
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    Thread Starter

    More info

    I can get those numbers. The pilot lights the burners for seconds and are now turning off once or twice before actually staying on as they should. The tech says it is a slow moving gas valve. Not sure what that means.
    To answer previous questions:. The furnace is vertical. Heat runs are in the attic. Yes AC coils.
    Last edited by Warmest; 12-05-2019 at 10:04 AM. Reason: Add info

  7. #33
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    25,680
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    Quote Originally Posted by Warmest View Post
    I can get those numbers. The pilot lights the burners for seconds and are now turning off once or twice before actually staying on as they should. The tech says it is a slow moving gas valve. Not sure what that means.
    Means hes Full of it!

  8. #34
    Join Date
    Nov 2019
    Posts
    6
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    Thread Starter
    Tell me more. I need info to call him on his BS.

  9. #35
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    25,680
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    Quote Originally Posted by Warmest View Post
    Tell me more. I need info to call him on his BS.
    Tell him to get the documents on your slow moving gas valve...………………….

    Better to just give up and find a different contractor!

  10. #36
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    10,055
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    Quote Originally Posted by pecmsg View Post
    Means hes Full of it!
    Not necessarily. Some Carrier/Bryant furnaces did have a slow opening gas valve. However if the furnace has a 3 wire pilot it sounds more like the pilot switch is opening and closing at start up as I believe was mentioned before.

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