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  1. #27
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    May 2017
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    Very curious how you test safeties.

    I usually just change filters, clean sensors, checks amps on inducer and blower, clean and inspect pressure switch tubing, observe flames, check blower conditions with a mirror. Then I ask the customer how the system has been and that will usually lead me to either inspect other things or leave it as it is.

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  3. #28
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    Oct 2017
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    Crossville, TN
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    It sounds like you are a ACE. ACE referring to Don't advertise your company.
    Last edited by beenthere; 12-10-2017 at 06:29 AM.

  4. #29
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    Sep 2016
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    Omaha
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    If your not using a combustion analyzer why are you adjusting gas pressure? Many times I adjust that up/down according to oxygen lvl, an CO ppm, and several other factors.

  5. #30
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    Apr 2012
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    Pasadena,Maryland
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    Quote Originally Posted by CircusEnvy View Post
    I found one at about 2 IWC. Turned it up to 3.5 IWC and that's when it occurred to me that someone turned it down because this furnace was way oversized for the duct work.
    Is that an acceptable practice to turn down the gas pressure when the unit is oversized. I had a Manuel J done on my house when I moved in because I intended to replace the furnace right away. I put in what the Manuel J said I needed and for 10 years I had to replace the limit about every two years. Finally I replace that furnace with a smaller btu furnace but a 90 plus which gave me about the same output and that one works great.


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  6. #31
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    Jul 2013
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    Richmond, VA
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    Quote Originally Posted by Flashg21230 View Post
    Is that an acceptable practice to turn down the gas pressure when the unit is oversized. I had a Manuel J done on my house when I moved in because I intended to replace the furnace right away. I put in what the Manuel J said I needed and for 10 years I had to replace the limit about every two years. Finally I replace that furnace with a smaller btu furnace but a 90 plus which gave me about the same output and that one works great.


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    If it's outside manufacturer specifications or code, it's not acceptable.

    Generally, 3.2-3.8 IWC is an acceptable pressure on single-stage natural gas furnaces. If your furnace was overheating, that suggests it's overfired or the duct work is undersized (more likely issue).

    Sent from my XT1585 using Tapatalk

  7. #32
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    Apr 2012
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    Pasadena,Maryland
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    Quote Originally Posted by CircusEnvy View Post
    If it's outside manufacturer specifications or code, it's not acceptable.

    Generally, 3.2-3.8 IWC is an acceptable pressure on single-stage natural gas furnaces. If your furnace was overheating, that suggests it's overfired or the duct work is undersized (more likely issue).

    Sent from my XT1585 using Tapatalk
    Unfortunately I believe that it is the duct work, but my home is on a concrete slab and the duct couldn't be improved. It also wasn't built with AC in mind as it's an older home. The Manuel J called for a 3 ton but no way could that cheesy duct worth handle that. So I ended up adding insulation and dropping to 2 1/2 ton


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  8. #33
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    Apr 2012
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    Pasadena,Maryland
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    Quote Originally Posted by Craigmeednj View Post
    I got into the habit of using my nanometer to make sure the gas pressure is correct on the inlet and outlet. I make sure the draft inducer is pulling well over the pressure switch. Is this not needed when doing my PM


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    I haven't seen anyone on this thread say if they check the heat exchanger. Or at least the flame pattern for disturbances when the fan is running. Is this not something that most company's want checked along with all other safety's and limits. We also check capacitors on fans.


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  9. #34
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    Mar 2013
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    Billington Heights, NY
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    Quote Originally Posted by Flashg21230 View Post
    I haven't seen anyone on this thread say if they check the heat exchanger. Or at least the flame pattern for disturbances when the fan is running. Is this not something that most company's want checked along with all other safety's and limits. We also check capacitors on fans.


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    Post 14. The HE integrity can be determined with a CA.
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "I’m going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

  10. #35
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    Apr 2012
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    Quote Originally Posted by HVAC_Marc View Post
    Post 14. The HE integrity can be determined with a CA.
    I have never heard that a ca could determine the integrity of a heat exchanger.

  11. #36
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    May 2014
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    Bay Area California
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    I'll look at the 'flame pattern' on just about every heater I fire off. But quite frankly, it's more out of habit than anything. Flame Pattern just doesn't tell you much if anything any more. Why, you may ask? Because that is an old school trick.

    Used to be big fat wide cells making up the heat exchanger. And no induced draft or combustion air blower. Nowadays, with little skinny cells [for greater heat transfer], and the flame/heat being forced through the cells, it's unlikely you'll see any disturbance in the flame from a crack in a heat exchanger.

    Now if you run across an older 70% efficiency unit, with no combustion blower . . .


    Quote Originally Posted by Flashg21230 View Post
    I haven't seen anyone on this thread say if they check the heat exchanger. Or at least the flame pattern for disturbances when the fan is running. Is this not something that most company's want checked along with all other safety's and limits. We also check capacitors on fans.


    Sent from my iPad using Tapatalk
    A skilled Tech would solder a relay on that board and call it good to go.

  12. #37
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    Mar 2013
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    Quote Originally Posted by Flashg21230 View Post
    I have never heard that a ca could determine the integrity of a heat exchanger.

    For example, because it's the simplest one, if the O2 rises when the blower comes on the HE is faulty.

    There's multitudes of threads on here about it.
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "I’m going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

  13. #38
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    May 2017
    Location
    Brooklyn
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    Quote Originally Posted by Flashg21230 View Post
    I haven't seen anyone on this thread say if they check the heat exchanger. Or at least the flame pattern for disturbances when the fan is running. Is this not something that most company's want checked along with all other safety's and limits. We also check capacitors on fans.


    Sent from my iPad using Tapatalk
    I stated that I observe flame patterns before and after blower comes on. If it doesn't seem right I'm pulling the blower or whatever I have to and inspect it.

  14. #39
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    Mar 2015
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    Hamersville, Ohio
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    Quote Originally Posted by Flashg21230 View Post
    Unfortunately I believe that it is the duct work, but my home is on a concrete slab and the duct couldn't be improved. It also wasn't built with AC in mind as it's an older home. The Manuel J called for a 3 ton but no way could that cheesy duct worth handle that. So I ended up adding insulation and dropping to 2 1/2 ton


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