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Troubleshooting Less than Perfect Operation

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by kmachn, Sep 26, 2012.

  1. kmachn

    kmachn Member

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    Installed a Cumberland Gap in our basement ~2 years ago, and have really enjoyed it but have never felt like it was really working quite right. Sure, I can get it hot and burn it pretty good, but seems like I really have to fight with getting it started sometimes. I have suspected wood, but last year was far enough ahead to use well-seasoned wood to eliminate that as a possibility.

    Well, decided to remove a pre-fab ZC fireplace and install the QuadraFire 7100 upstairs this year, and gave it a couple small break-in fires last weekend to cure the paint and make sure everything was working correctly before starting the cosmetic/finish work. It put out some serious heat, and I have never had a fire start so easily. It got me wondering about the Gap and some of the difficulties there.

    I used a flame to check for problems; air leaks in stove, pipe, etc. I didn't find any leaks in the stove, but noticed that my connection from the double-wall stove pipe to my "Ceiling Support Box" had an air leak, pulling air in from the living space up the chimney. Naturally, I want to fix this problem.

    According to the installation instructions from the manual, I think I did it right. A link is below. I have a doulbe-wall pipe directly connected to the ceiling support box. The problem, is that I basically had to attach the "outer" wall to the only pipe on the ceiling support box, which is designed to be connected to the "inner" pipe. Seems there should be a specific adapter, but I can't seem to identify it in the installation instructions.

    I'm happy to provide more info, but this is a long start so any feedback at this point would be helpful. I also thought about using stove cement to seal the leak, but #1 it would just be masking the problem, #2 I want to connect this pipe when I clean the chimney system and #3, least importantly, it could be a bit of a cosmetic issue if not done perfectly. Thanks for suggestions

    http://www.mtlfab.com/media/L801.pdf

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  2. begreen

    begreen Mooderator Staff Member

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    This sounds like it may be weak draft. Can you describe the entire flue system on the CG including pipe diameter and overall length? How well sealed is the connector at the stove flue outlet?

    Basement installations are frequently in negative pressure zones. They can lack the robust draft of a first floor installation. Have you looked for items in the house that may be competing for combustion makeup air? This article may be helpful.

    http://www.woodheat.org/all-about-chimneys.html
    A1Stoves.com likes this.
  3. kmachn

    kmachn Member

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    Thanks for the reply begreen. I should've given more information up front, but I tend to get wordy. The chimney uses the 6" Metal-Fab Class A TempGuard chimney pipe. I don't remember the exact length of chimney, but I think it is around 24 feet. I know it is at least 20 ft. It runs through conditioned space on the first floor and a sheet rock chase through the attic, ultimately terminating through the roof. There are a couple of offset/resturns, I think one 15-degree and one 30-degree. The stove-pipe is not really sealed at the stove flue outlet...assuming you are referring to the double-wall pipe connection directly to the stove. I could check that with a flame this evening, which I suppose could be an issue. But I definitely know there is a lack of seal from the stove pipe to the ceiling support assembly. Is it absolutely necessary to seal it? I will if I need to, but with all of the elbows in that chimney pipe, I have found chimney cleaning easier to disconnect the stove pipe and do a push/pull with the wire brush with one person on the roof and one person in the basement.

    I also installed an OAK last year, which definitely seemed to help with indoor comfort and probably with getting the fire started also. So I don't think it shouldn't be a negative pressure issue. However, using the flame, I did also find that 1 of the 3 air inlet holes at the front of the stove didn't seem to affect the flame...that was with the air wide open. I'm hoping it is just simply clogged with ashes and can be cleaned out with a vacuum or some compressed air.
  4. begreen

    begreen Mooderator Staff Member

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    Normally there is no need to seal at the ceiling support box. The twist lock connection is supposed to seal well. However, at the stove level the fit with some stove flue collars can be sloppy. That is the first place I would inspect.
  5. kmachn

    kmachn Member

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    I will double-check the stove connection, you are probably right in that it is not sealed well.

    On the other hand, there is not a twist-lock connection at the stove pipe>ceiling support box connection. Here is the basic rundown...

    Cumberland Gap>Telescoping DW pipe>45-degree offset>18" DW pipe>45 return>Ceiling Support box

    The instructions just say "secure with sheet metal screws" to the ceiling support box. The problem, is that the crimped pipe is 6" on the ceiling support box. So, I am basically trying to screw an 8" "outer" wall into the 6" crimped section of the ceiling support box. It doesn't seem like a good system, seems like I am missing a piece but the installation instructions don't seem to indicate another piece is needed.

    I'm hoping you (or someone) can point out to me a flaw in my interpretation of the installation instructions, or a flaw in the instructions themselves. It seems like a bad idea to screw an 8" "outer wall" of a DW pipe into a 6" crimped section and assume it is sealed well.
  6. Dairyman

    Dairyman Feeling the Heat

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    Metal-Fab has a slip connection on the stove pipe. Could your screws not have penetrated the ceiling support pipe and instead pushed it in?
  7. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    8" OD? The DW connector should be closer to 6-7/8" on the outside. DW connector generally has a 3/8" air space between the inner & outer pipes... Are you missing the chimney pipe adapter for the support box?
  8. kmachn

    kmachn Member

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    Dairyman...I doubt it, but that is a possiblity. Something else I can check. I am always pretty careful with the self-tapping screws, because I know that can happen. I also think I would have noticed when I cleaned the chimney last year, and disconnected the pipe, if that were the case but I'll check nonetheless.

    DAKSY...My estimate of 8" is probably wrong. I guess the point is that it is a larger diameter pipe screwed into a crimped, smaller diameter pipe so I don't see how I could possibly get a good seal.

    I'm not sure if I'm understanding your question, but it sounds like you are asking if I am missing an adapter between the chimney pipe and the stove pipe??? If so, the ceiling support box basically serves as that adapter. If you are asking if I am missing a DW pipe to single pipe adapter/ceiling support box (since the ceiling support box has a single crimped pipe) then it is a real possibliity. The installation instructions seem to indicate that adapter is only for the stove to DW pipe pieces. I would think that inverting that piece, for the other end, wouldn't work right...unless Metal-Fab makes another piece I am unaware of.
  9. Dairyman

    Dairyman Feeling the Heat

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    Your not missing anything that I'm aware of. Maybe you need to expand the male side a little bit. Mine went together with a good amount of pressure, no slop.
  10. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    If there's a short section of crimped pipe hanging from the support box, then that's the adapter. It could be the length of your fasteners. They should be at least 3/4" long to get thru the outer diameter, the airgap & the inner pipe..
  11. kmachn

    kmachn Member

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    I'll take it apart tonight and get a closer look, but the screw length is a good point. I can almost guarantee they are only 1/2" self-tapping stove pipe screws. I remember thinking there was almost no room to make the connection, very little space. I'll review everything this evening and re-post, with pictures.

    Any ideas on the air inlet hole that is clogged? Should this be as easy as a vacuum and/or compressed air through the hole?
  12. begreen

    begreen Mooderator Staff Member

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    I predrill a pilot hole before screwing the pipe together to help start the screw and avoid puckering the inner liner.

    Did you check the insulation blanket to make sure it is laying flat and not bunched up at the back of the stove.
  13. kmachn

    kmachn Member

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    I pulled the stove pipe from the ceiling support box. Attached is a pic. I apparently screwed threw the ~1/2" thin portion at the top of the elbow, into the ceiling support box. From what I am reading here, I probably should have drilled ~1" lower, through both walls, and into the crimped section of the ceiling support box. Thanks for the pre-drilling suggestion, I'll make sure I do that. Would you suggest I purchase a new elbow, or just try to re-use this one?

    You can see in the picture that there is a definitely line from where the ceiling support box pipe was inserted. It "looks" like it was a pretty good fit. Could moving the screws make much improvement here?

    I did consider checking the insulation blanket, but have not done it yet. I know I checked it closely to make sure it was right before connecting the stove pipe last year, but will check again when I get home this evening. I have also read (on this forum) about creosote powder accumulating on the top of the ceramic blanket and restricting air flow. I doubt that is much of an issue since the stove is working OK, but thought I should re-check that too.

    Attached Files:

  14. kmachn

    kmachn Member

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    I hope I don't get in trouble with the moderators, but I'm reviving this thread. I have been using my QF 7100 daily for about 2 weeks now and fired up my CG last night to again be somewhat disappointed with the performance. I am not necessarily disappointed with the heat output, as there are some things in the living space (basement) that need to be addressed before I can accurately assess that. But, there is a noticeable difference in the way these two stoves burn. My wife has commented on it too, and she doesn't usually get in to the details that much.

    They are both QuadraFire and I am not aware of any reason why they should function differently (although the 7100 does have a bigger firebox). Both have an OAK installed, the CG has a 6" Class A ~23 feet of chimney and the 7100 has ~16.5 feet of 8" double-wall/air-cooled chimney. Yet the 7100 seems to have better air flow throughout the firebox. No air leaks on the CG (or stove pipe), I cleaned and double-checked.

    I am wondering if the secondary burn tubes are getting enough air when I dial it down. The fire still burns, but it seems like the flames are always from the bottom and not much at the top. It's a clean burn, no smoke from the chimney and clean glass. But I don't seem to have the "gas flames" around the holes at the burn tubes like I do with the 7100. And, as mentioned before, it doesn't seem like the fire "moves" around the firebox. Seems to stay in one place. Is it possible/likely that there is an air restriction to the secondary burn tubes? How would I check this? Do I have unrealistic expectations?
  15. kmachn

    kmachn Member

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    OK, I could really use some help here. There really is NOTHING coming from my secondary burn tubes. Stove top is 625 and stove pipe probe is reading 675F. At the moment, I have the air dialed down to ~1/4 open, 3/4 closed. No smoke coming from the chimney and active flames in the firebox. But there is not anything happening at the top of the firebox. All of the flames are coming from the doghouse. I know it was performing better than this last year. Perhaps I made a mistake when putting things back together after cleaning this year, but even before I never get anything like the secondaries on my 7100. Although I'm getting a clean burn, I really think I could be getting more efficiency from this stove.

    Really, any suggestions on what else to check? Any way to check if there is air getting to the secondary burn tubes without dismantling the whole stove?
  16. madison

    madison Minister of Fire

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    Let it cool off, empty firebox, remove baffle - and give the shop vac a workout. Look at the stove design diagrams and look/suck out ash plugging air paths, depending on baffle design, when it is removed break it down and clean it out.

    Any chance the "Oak" is plugged (mice nest , bees nest etc)? Have you tried disconnecting the OAK?
  17. kmachn

    kmachn Member

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    Thanks for the feedback, Madison. I gave the Shop Vac a hefty workout a couple of months ago when I did my cleaning. I cleaned the air inlet at the bottom really well and turned the Shop Vac hose around and blew air through the OAK (I made sure there was nothing in there first) to blow anything out that might have been a little buried. My concern was with the dog house though, not the burn tubes. Maybe there is something up there that I am missing. I also removed the burn tubes and cleaned them, although there was nothing in them to clean. I know I replaced them in the correct places again, but perhaps I got something else mixed up on the reinstall. I know the holes are facing the right direction, too.

    I'll see what I can do about the OAK. I don't think it is plugged, but it might need a redesign. I am willing to try. Just for my understanding, can you explain how the OAK could be the culprit when there seems to be plenty of air coming in at the bottom?
  18. madison

    madison Minister of Fire

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    Place your hand over your mouth and try to breathe... You can get some air, but not enough to live comfortably with -- same with the stove - possibly, it is getting some air, but not enough for the manifold to function.

    As begreen and others are guessing, lack of draft can reduce the airflow into the stove, restrictions of airflow into the stove could excacerbate the marginal draft .

    One possible troubleshooting idea is to just crack the door - and do not leave the room during this troubleshooting -- if the firebox shows increased burning and not smoke spilling into the room - you need to rule out inflow obstruction as well as marginal draft. Depending on the OAK hookup, you could also do the same thing with the OAK -- disconnect and observe the fire -- if it show obvious increase in burn rate it could be restricting the airflow into the stove and into the manifold tubes.

    I took a gander at the parts list pdf for the Gap and could not see how the secondary air gets to those three manifold tubes.

    But on page 14 - 15 of the install manual ( http://hearthnhome.com/downloads/installManuals/man_cumbGap.pdf ) it seems as though there is some sort of baffles and diverters etc that could present problems if not installed and manually formed correctly or deformed ....And maybe they have moved and the air is not getting to the manifold tubes??

    Looks like a weekend project of troubleshooting, removing and repairing.

    Post edited after rereading previous posts....
  19. laynes69

    laynes69 Minister of Fire

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    I don't know anything about that stove, but on our furnace the more primary that feeds the fire, the less action at the tubes. While it's hot, maybe close down the air as much as you can and if the secondary is fixed you should see action there. If not then there's an obstruction, or somethings isn't right. Normally just about everyone posts with a stove temp higher than the flue temps, in your case their equal. That seems to me there's a bit of heat being pushed through.
  20. kmachn

    kmachn Member

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    Good information. I know our house is pretty tight (verified with a blower door test) which is why I installed the OAK. It seemed like draft was better after installing the OAK, but to be honest it is quite possible that the incoming air has never been enough to be what it was designed to be. I will try some of these tests and see what I can learn.

    As for the baffle diverters, I actually did not install them because I interpreted from the manual that they were only used when the stove was venting horizontally, and mine vents vertically. After re-reading, it says "required" in all horizontal installations. Should I assume this is optional in a vertical installation, or that it is only used in the horizontal? Any ideas? I still have the pieces, so I can install them if they may help.

    The Good Lord knows I don't need another weekend project, but I definitely want to get this figured out so I am up for the challenge. Thanks again
  21. kmachn

    kmachn Member

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    That is what has me really confused. As a dial the air back, I'm not getting more action from the secondary burn tubes which is what makes me think the air coming in is good, but there is an obstruction/problem between the shift from primary to secondary. Interesting point about the stove temp and flue temp being equal. I guess I had not paid enough attention to notice that others report stove temps being higher than flue temps. When you say "a bit of heat being pushed through", you're saying that there is probably more heat being pushed through the stove (and not enough staying in the stove) than should be?
  22. laynes69

    laynes69 Minister of Fire

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    Usually the more primary air that's put into a stove, the more heat that is pushed out the flue. What you have may be just fine for that stove, I don't know.

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