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draft gauge operational

Discussion in 'Modern EPA Stoves and Fireplaces' started by Coyoterun, Nov 23, 2017.

  1. Coyoterun

    Coyoterun

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    It's a rough install but it's operational. I'll see how I like it, and do a proper layout for the stove's instrument panel later.

    In the mean time, it's kinda fun to watch the needle respond to damper adjustments. Everyone like pictures, correct?

    Right now, it's 50* outside with a 300* flue, and I've still got 0.1" of draft. What do I get when it's actually cold out!?!

    What's the recommended draft for an Idea Steel?
     

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  2. CDF_USAF

    CDF_USAF

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    I think you might want to add a piece of metal tubing if its going to stay hooked up all the time so you don't get a smokey surprise. As for the draft, it will get stronger when the temp drops.
     
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  3. Coyoterun

    Coyoterun

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    That's hi-temp silicone tubing, rated to 500 degrees operating temp. It's on a stainless steel probe in double wall stove pipe. I will indeed be surprised if it melts off there.
    But even it does melt off the probe barb, the rest of the hose will fall away from the stove.
     
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  4. CDF_USAF

    CDF_USAF

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  5. jdonna

    jdonna

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    I'm not surprised to see those numbers. I've measured .15-.20" when the wind is really cranking on higher burns in the cold weather.

    I think part of the issues is the bends in the connector pipe actually increase the vacuum. We are not seeing actually cubic feet per min of flow which is the biggest factor.

    Kinda like synching a carbs, close the throttle plates down and vacuum increases in the system, but idle drops. When setting a barometric damper, you measure the drop across the two planes totally different.

    I'm just betting draft measurements are probably most accurate and referenced from a manufacturer on chimney setups that go straight up with no bends or T's. I'd love to have a day playing with temps and manometers in a lab setting for references out in the real world. Maybe someone else can chime in on this as well.

    I've 26 feet of stack with a 90 bend and a T on it.
     
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  6. Coyoterun

    Coyoterun

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    As you mention, closing the air control increases the draft reading. That's increasing the restrictions before the draft meter probe. I'm not so sure the elbows after the probe would increase draft reading, I would expect them to lower it. The damper is located after the draft probe, and I was a bit surprised how sensitive the meter is to the damper position. Even small changes in the damper position are instantly reflected by the needle on the gauge. Flames in the fire box aren't nearly as responsive to the damper.

    I have thought about getting another setup and putting the probe above the T-connector of the chimney liner, back opposite the wall thimble. There's 29' of flex liner, mostly straight up, above there. But it doesn't seem worth blowing another $100 right now.
    Before that, though, I want to get another Auber temp probe in the same place. Of course, those probes would need to be pulled out every time I want to run the soot eater.
     
    Last edited: Nov 24, 2017
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  7. Flamestead

    Flamestead

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    We ran one in the T, between the stovepipe damper and the stove. I'd have to check old threads, but am pretty sure with cold and wind we were up in the .2 vicinity.

    The IS did quite well on this chimney without the stovepipe damper- probably ran the best of the three (PH, AS, and IS) on this setup. The AS didn't like it as well, which is why we got the damper and did measurements.
     
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  8. jdonna

    jdonna

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    I think your biggest indicator will be burn times, stack temps and stove top temps above anything else.

    I have my 4th stove on my flex liner and just upgraded to two 45 degree elbows and double wall pipe. It's important to keep the stack temps up on taller setups with how low of temps these cat stoves run throttled back. I always had a good amount of buildup in my single wall pipe with my fireview due to the pipe cooling.

    I'm been converted a believer after much resistance on getting rid of the turn key damper. You lose some effective diameter internally within the stack and a nice air infiltration air leak into the connector pipe.

    Many others have said the cat stoves like a strong draft.

    You just have to adjust your open bypass burns, when you start closing down and what the weather conditions are like.

    Some some random rambling of my experiences.

    Enjoy dialing in that awesome stove!
     
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  9. brenndatomu

    brenndatomu

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    I dunno bout cat stoves, but the tube type stoves that I've seen recommended draft numbers on were in the -0.04 to -0.06" WC range...and most wood furnace manufacturers forbid operating higher than -0.06" WC...and some as low as -0.03" max!
    I, and many (most?) of the people I know that run a manometer use the Dwyer Mark II model 25. I have some NOS Dwyer 25s that I bought at auction...$35 would get ya one in your mailbox...just throwin it out there if you're interested...
    For Sale - Dwyer manometers
     
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  10. Coyoterun

    Coyoterun

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    We've finally been getting into actual cold weather, sub-zero temps. I'm really liking my draft gauge. It rarely goes above .2", even with -10*F and 500* stack temps. But it seems to run pretty close to that even with +10* outside temps. I haven't had the combination of cold temps and high winds yet, to see what happens then.

    Before I got the draft gauge installed I wasn't really ever using the key damper. I was just using the air intake control to control the burn. That meant I often had to close the air intake down to the last small notch to keep the stove from running away under high draft conditions. That was fine for the main burn, but it wasn't enough air during the coaling stages. The coals took forever to burn down, and the stove would rapidly fill up with them.

    Now, with the draft gauge, I can get the fire going well, slowly turn the air intake down to the first large notch, and then use the damper to turn the draft down to about .10". That setting seems to be working quite well, giving me 8-10 hours or so of heat without nearly as many coals left over when I go to refill.

    For some people, it would probably work to use the secondaries as a visual draft gauge, and adjust the the key damper according to them. It doesn't seem to work as well for me. I need the hard instrument numbers to really feel confident in my settings.
    I understand many people wouldn't find a use for it, but for my set up I really like having a draft gauge hooked up all the time.
     
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  11. brenndatomu

    brenndatomu

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    Glad to hear you are having good success there...you say you turn it down to -0.10", that seems a little high from what I'm familiar with...any idea what they call for on the IS? -0.04 to -0.06" WC would be a common spec for the units that I've seen...but maybe I'm all wet on the IS specs...
     
  12. Coyoterun

    Coyoterun

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    I have no real idea if there is a recommended level for the IS. I know Woodstock says all you really need to run one is the flue temp gauge. I picked -0.10" because it seems to work for my setup. Much lower than that during the hot stage and the fire can stall out. When the fire is down to coals and the flue temp is down, then the draft will be down in that -0.05" to -0.06" range at the same damper setting. So it works better to leave it a little high when the flue temps are high. That way it doesn't drop too low when the flue temps drop.
     
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  13. brenndatomu

    brenndatomu

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    Yeah I suppose a cat stove could be a lot different than others
     
  14. Flamestead

    Flamestead

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    This is in line with what they expect (maybe -0.07) as a typical draft. Our flue drafts stronger (up to -0.20) but the IS handled it ok and we didn’t know better at the time. The AS didn’t seem to like it as well, so under direct guidance from WS we added a damper in the flue and played with a barometric damper. This was after the IS, so I can’t directly compare how much better it might have run with less draft.