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  1. #1
    Join Date
    Apr 2002
    Posts
    279
    i am having a problem with a reznor unit heater. i dont have the model #. 125,000 btus. on me but here goes.
    its newly installed last week. the unit tripped flame rollout. when i returned to find problem it would lock out on flame sensed while gas valve is not energized.

    there is a lingering flame when the gas valve shuts off for about 10 seconds. this is what the sensor senses.
    the unit is vented horizontally about a 4 ft run max.
    it does it with the flue conected or not. it does it at any gas pressure.
    is the draft inducer motor not alowing enough draft?

  2. #2
    Join Date
    Feb 2001
    Posts
    35,838
    Many unit heaters do not draw well, they are hung close to the ceiling and there isn't enough vertical height for proper draw, also the bldg may have some negative pressure in it. I have seen many old unit heaters operate under those conditions, and no one knew cause older ones didn't have the rollout sw. On new reznors I sell and install I go with the better models with built in draft inducers, just installed a 250K one last week. I have no problem with those.
    2 things ya can do at this point.
    1- Possible cheap out method, add a whirly bird spinner cap on top of the flu, they can really help sometimes.
    2- Install a small additional Tjerland draft inducer, with a time delay run on it or rewire the one you have to stay on for a period of time.


    [Edited by Diceman on 01-31-2004 at 10:37 AM]
    Hey cockroach, don't bug me!

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  3. #3
    Join Date
    Jan 2002
    Posts
    1,895
    Still having flame 10 seconds after the valve is supposed to be closed sounds like a problem with the gas valve.

  4. #4
    Join Date
    Feb 2001
    Posts
    35,838
    True, I missed that, valve could be bad.
    I thought he was talking about residual heat still lingering.
    Hey cockroach, don't bug me!

    www.AskTheDiceman.com

    www.TheColdConspiracy.com

    www.Pennwood-HVAC.Com

    Bring Em Home....

  5. #5
    Join Date
    Oct 2002
    Location
    ottawa
    Posts
    309
    Reznor= junk

    I have found more cracked heat exchangers on reznor equipment than on all others combined, I really dont know how they can still be in business, maybe in some areas a couple of small cracks are OK when installed in garages and warehouses.

  6. #6
    Join Date
    Jan 2004
    Location
    Massachusetts
    Posts
    665
    Check the polarity of the incoming power. Reznor setups react bad to reversed polarity.
    "The value of quality is long rembered after the thrill of low price is forgotten."

  7. #7
    Join Date
    Sep 2003
    Location
    western canada
    Posts
    373
    Most UH I worked on had 24v to the stat.
    On a call for heat it would power up the flame sensing device, which in turn would power up pilot, sense the flame if there was any, and power up main gas valve.
    Call ends, you lose power to flame sensing device, gas valve included.
    No lock out.
    Roll out switch should be wired in series with the stat/ flame sensing device.
    Change the gas valve, most likely problem.
    work to live not live to work

  8. #8
    Join Date
    Apr 2002
    Posts
    279
    the gas valve is closing 100% closed. i can put my ginger over the orfice and the flame still lingers. i also checked with my magnahelic no pressure at the orfice when the valve looses power
    maybe a better way to discribe it is simular to an old ribben burner when the gas valve shuts of it takes maybe 3 seconds for all the gas to burn off in the burner.

    m# UDAP 125
    S#BBE79Y2N63979X

    i havent taken the burner apart to see whats inside but i will try to explain what it looks like.

    from the orfice it goes into about a 1.5 inch tube that goes into a rectagular box at a 90 deg angle. from there i asume its diverted into each heat exchanger cell

  9. #9
    Join Date
    Jul 2001
    Posts
    3,112
    Is this on LP? If so, did the individual doing the conversion install the adaptor on the inlet venture tube? IF not on lP, sounds like a bad gas valve. How does the vent terminate after 4 feet? Find the instructions, you may need to increase the vent lenght to a minimum of 5 feet.

  10. #10
    Join Date
    Jul 2001
    Posts
    3,112
    Call a qualified service technician. Don't burn your building down working on something you are unfamiliar with.

  11. #11
    Join Date
    Feb 2001
    Posts
    35,838
    Yeah, now I know what ya mean, just like the one I put in last week, very weird design huh? I noticed mine had a good draw on the vent already. That seems to be your problem, put a spinner cap on it or wire the draft inducer to run for a time after the flame shuts off. The Reznor I got had 2 nuts missing from the fan motor, it was hanging down, new in the box like that. Thats an odd size too, lucky I had a few of em laying around in my misc collection of junk.
    Hey cockroach, don't bug me!

    www.AskTheDiceman.com

    www.TheColdConspiracy.com

    www.Pennwood-HVAC.Com

    Bring Em Home....

  12. #12
    Join Date
    Apr 2002
    Posts
    279
    i am the qualified service mechanic who installed this thing. i can assure you its not the gas valve. just read my last post.

    whats this spinner cap you are talking about diceman? is it like some of the older roof vents that spin with the wind or hot air rising thru the attic?

    the inducer runs for about 30 seconds after the gas valve turns off.

  13. #13
    Join Date
    Feb 2001
    Posts
    35,838
    Yeah, that's what the are but you need to really investigate the flu and all that, you did check it on the roof right? Do you have a good draw on the flu, you need to find out. 30 sec of extra run time should clear out any heat, not sure what is going on here, something weird. Start with the flu, draw, etc.
    Hey cockroach, don't bug me!

    www.AskTheDiceman.com

    www.TheColdConspiracy.com

    www.Pennwood-HVAC.Com

    Bring Em Home....

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