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  1. #1
    Join Date
    Jun 2002
    Location
    Bemidji, Mn
    Posts
    3,573
    Had a call today, fireplace was dropping out after running a few minutes.

    Generator was putting out 400+ before the heat call, 200+ on heat call.

    Thermocouple was hitting 20+..

    After the MV opens it runs for about 20 seconds, then both the pilot and mv drop out?

    Still getting 200+ at the gen, cant read the thermo while the system is running, dont have that fancy adapter, which I will order as soon as possible just for calls like this. Im thinking the pilot mv is dropping below 15 after the mv opens, ..

    Also, when the glass is removed, it doesnt do this at all. Works fine. Where do these systems take intake air from? Didnt look at the venting, no ladder today, borrowed. Hadnt used it in 2 weeks figures.

    Any ideas appreciated, Chad
    You picked a fine time to leave me loose wheel...

    http://rapalaguy.spaces.live.com/

  2. #2
    Join Date
    Oct 2003
    Location
    Minnesota
    Posts
    148
    Well need more info to start. Is the flame pretty good right up until it quits, or is it fading out (what I call gosting out).Need to know the venting setup. If it is a insert most have two pipes fresh air and exhuast. How tall is the chimney. Check all venting for restrictions. If unit works with glass removed I would be leaning towards venting problems to start with. Then if all that checks out go back to the pilot. Are you losing the flame to the thermocouple. Might look at a pilot schield. See if this gets you anywhere. Wait to hear back.
    Helgy

  3. #3
    Join Date
    Apr 2002
    Posts
    1,383
    <<Also, when the glass is removed, it doesnt do this at all. Works fine. Where do these systems take intake air from? Didnt look at the venting, no ladder today, borrowed. Hadnt used it in 2 weeks figures.

    >>


    This is the classic symptom of a pilot flame that is being starved for oxygen and pulling away from the thermocouple. I'd look at the pilot flame very carefully with the glass on and see if the flame doesn't lift off the thermocouple.

    If so, you have a combustion problem to fix. That could be an overfired burner, improperly installed vent pipe or cap, insect webs in the fresh air pipe or a variety of other things.


    Seattle Pioneer

  4. #4
    Join Date
    Nov 2002
    Location
    Lisle,Illinois
    Posts
    526

    Cool

    Check that pilot flame remains on top 3/8" of thermopile when main burners are on.If flame is closer to middle thermopile wont make rated output.Quite often when main burner is on pilot is starved if logs are misaligned.

  5. #5
    Join Date
    Jun 2002
    Location
    Bemidji, Mn
    Posts
    3,573
    Its a DVS-36-1

    Went back today, something isnt right here. Where do these units get combustion air from? it has the 2 piece exhaust with the Combustion on the outside of the pipe, but then when it enters the fireplace, it goes in just with the center, a 6" pipe. There is no intake (combustion) air anywhere. It has a pressure door relief flap that sits on 3 holes..Thats it.. Damn I wish I had my Digital with me. Hard to explain..

    The Pilot stays on fine, but when the MV kicks on, it takes the pilot out (Thermocouple) after a few minutes, the flame is really starved for air..

    Gotta love fireplaces.......



    [Edited by Chad711 on 02-25-2004 at 05:34 PM]
    You picked a fine time to leave me loose wheel...

    http://rapalaguy.spaces.live.com/

  6. #6
    Join Date
    Jun 2002
    Location
    Bemidji, Mn
    Posts
    3,573
    Found that they pull from the bottom by the burners.. FYI, Ill check it out asap and reply back, thinking the lava rock may have been overfilled and blocking the combustion air.......
    You picked a fine time to leave me loose wheel...

    http://rapalaguy.spaces.live.com/

  7. #7
    Join Date
    Dec 2002
    Location
    Minnesota
    Posts
    116
    Could there be a leak or hole in the inner vent causing the flue products to recirculate? When you say it is starved for air does the main burner flame "float" up into the combustion chamber? You have probably seen this on Coleman MH furnaces when the intake gets plugged with snow, or with forest tent catepillars and you see a pilot outage. That's what I would check, probably a royal PITA to see if it is recirculating though. Might have to pull the vent apart to really tell.

    artist

  8. #8
    Join Date
    Sep 2003
    Posts
    37
    Not sure on this Empire, but I've had fireplaces that send the combustion air down inside a double wall within the firebox. The gap is less than 1/2 inch, and bugs love to hide there. I had to remove a fireplace, take it apart and remove thousands of moths to get the thing working.

  9. #9
    check out http://www.empirecomfort.com also thermocouple runs the pilot/ thermopile runs the t-stat system system does sound like it is starving for air

  10. #10
    Join Date
    Jun 2002
    Location
    Bemidji, Mn
    Posts
    3,573
    I give up.. Cant figure it out, checked the lower combustion area, clear. Cant get on the roof too steep no roof ladder. Fireplaces sawk...

    You picked a fine time to leave me loose wheel...

    http://rapalaguy.spaces.live.com/

  11. #11
    Join Date
    Apr 2002
    Posts
    1,383
    <<I give up.. Cant figure it out, checked the lower combustion area, clear. Cant get on the roof too steep no roof ladder. Fireplaces sawk...
    >>


    Combustion problems on sealed up and direct vented fireplace are often a pain in the neck. There were a lot of good ideas on this thread.

    I wouldn't feel too bad, especially if you got paid for your time.


    You know you've been working on fireplaces too long if you catch yourself thinking that the so-and-sos who design fireplaces ought to make them easy to service, like furnaces....



    Seattle Pioneer

  12. #12
    Join Date
    Nov 2003
    Posts
    138
    Some great thoughts here already. Before you go jumping the gun, cover the basics: do you have adequate inlet gas pressure both static and burning? With everything else on at the same time? Ok, you measured thermocouple mv at standby. Yes, you need the little interrupter block to tap into the TC circuit so you can monitor the TC millivolts while burning. If you cannot find one in your local HVAC supply house, try Copperfield Chimney Supply at 800-247-3305. Under $10.00.

    Attach alligator clips, record your baseline, then fire up. The mv might rise momentarily but they usually then fall off into the upper teens and stabilize. If they keep crashing down, you have one of two things: a bad thermocouple or an overheating TC. TC's work off a 400 F temp. differential btw hot and cold junctions. If the pilot flame combined with the burner flame over heats it, the TC could drop out. If the vent is restricted, the unit overfiring, or anything else that induces too much heat or not enough cooling, the pilot can drop out. Same for an improper replacement TC. If the pilot bracket is not secured, it cannot act as a heat sink to cool the TC. I've seen misplaced logs and too much embers distort the burner flames enough to do it. Watch that pilot closely. If you see a clear, blu-ish flame lifting off it, that's usually in the venting.

    Aside from all the other ideas, it sounds like a problem with a restricted vent system given the limited info. here. Try to access the vent and feel & visualize the inner joints. If you think they might be sloppy and leaking, seal them with furnace cement. Verify the rise/run meets mfr. specs. If you have a tall, straight vertical run, it might be over drafting pulling the flame off the pilot. Most HeatNGlo and Heatilator's issue vent restrictors to use on these runs. May not be needed if elbows in the run.

    Is there a chance the installer left some insulation in the combustion air pathway? This is common with inexperienced installers and esp. on units that are capable of top or rear venting. Can you get a small inspection mirror and flashlight to peek up that air duct in the rear of the unit?

    I've seen Majestics ghost out the pilot due to a bracket located over the pilot. I cut off a piece of metal the size of a postage stamp and it ran like a champ.

    One last land mine to look out for: if you've had the glass off for awhile and it ghost out after having run ok previously, you probably warmed the cold combustion air intake creating a draft in it and it cannot prime itself. Just close it up with the pilot off for 30-40 minutes and try again. Once that air intake fills with cool, dense air, it should be able to thermosiphon fine.

    All sorts of goofy things fireplaces can do to trick and aggravate the most experienced Fp service tech, right S/P? You seem to know the joy I speak of.
    HTH,
    Doc

  13. #13
    Join Date
    Sep 2003
    Posts
    37
    Good post, Doc.

    I've run into reversed intake and exhaust pipes a few times. The fireplace acts exactly like this one due to reverse flow (exhaust out the intake). The weird thing is sometimes they work. Had one that was working fine for over two years before the problem showed up.

    If this fireplace is vented with coaxial pipe, take the venting apart and make sure the inner pipe wasn't crushed during installation.

    First thing I'd do, though, is climb on the roof and see if a bird has nested in the termination cap.

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