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bypass vs mixing valve for return protection

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by goodwood, Mar 5, 2012.

  1. Fred61

    Fred61 Minister of Fire

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    I don't believe your on cycle needs to gas. It should just add enough air to replace the oxygen depleated air (wood gas) surrounding the fuel. A small amount of air should maintain some sort of combustion in the coals.
    The way I run my EKO the cycle timer isn't needed because I "batch burn" one hot fire per day but the cycle timer still cycles on during the one idle period I get when the storage tank is near maximum temperature. I'm usually not far from the boiler at this time in the burn and I've witnessed the cycle. I don't know what it's set for and have forgotten how to set it but it only runs about 6 seconds. That doesn't mean yours should be that short because of the positive draft closure on the Wood Gun. It will take more time to purge the oxygen depleted gas from the chamber.

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  2. avc8130

    avc8130 Minister of Fire

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    I was reading another WG's experience and he mentioned that he had the cycle timer with just 1 clip every hour. Maybe I'll try that tomorrow.

    Each clip is ~120 seconds.

    ac
  3. jdkinohio

    jdkinohio Member

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    The
    Just went down to the garage and checked the drip pan in the cyclone. Record setting .5" of water in the pan. Last night wasn't that cold either, 30f vs 20f the night before. I think I'll remove the insulation and go back to the original setup. I have no plans to add the cycle timer. If I have to keep putting a pan in the ash try after I shut down, then I guess I'll stick with that. Better then having a wet stinky mess of caked ashes, and the bottom of the cyclone tray soaked. Even if it's a PITA!!

    I have a small natural gas fired boiler in a wood shop detached from my home. Tubing in concrete floor, etc.. This has a 4" flue that included a condensation "collector" (on the horizontal run out the wall) and drip loop of vinyl tubing. I don't recall ever seeing any condensation in it, but I'm thinking it wouldn't be too hard to fabricate something to do the same on my WG stove pipe. Something I'll think about while at work today, where I should be thinking work stuff instead!


    jdk
  4. Fred61

    Fred61 Minister of Fire

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    120 seconds could be too long. If my theory holds water (pardon the pun) the more low temperature burn sessions you have, the more condensation you're likely to see. I also could be totally wrong on my assessment. I don't recall having this problem as severe as what you folks are describing but I do live in a colder climate.
    You could build smaller fires in the evening and coast 'til morning after the wood is consumed in these relatively warm temperatures.
  5. jdkinohio

    jdkinohio Member

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    Did I mention that I am heating 500gals of storage water?

    I can't see the cycle thing working for me. As Fred61 mentioned, I think the heating and cooling of the cycles would just add to the problem. My goal (aside from providing heat for the house and not contributing to the retirement funds of the local energy providers), is to be able to sleep and leave the house without a fire burning. The boiler is in a garage that is under a couple of the bedrooms. I'm too fire paranoid to do it any other way. I'm sure the chance of something bad happening is very remote, but that's my decision. Based on that, I fire once a day when I get home. I have a hot fire that runs 1.5 to 2 hours before it hits the limit. At that point, my tank is at 190f. Stack is going to cool. Part of it runs through the attic, so the cooling is more intense. The odd thing is that I don't remember having this much issue with condensation last year. Pretty sure wood moisture hasn't changed that much. Will try the condensation "catch" option on the stove pipe, as I mentioned in my last post. Maybe that will catch the majority and eliminate the pan option.
  6. avc8130

    avc8130 Minister of Fire

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    I'm not sure how you define "low temperature burn sessions". It seems that if I keep regular firings, the boiler jumps to gassification instantly.

    Where are there warm temps? We are withing ~8 degrees of our design temp at night. I am waking up to 24F consistently.

    ac
  7. avc8130

    avc8130 Minister of Fire

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    If you are seriously worried about having a fire while you are asleep, you could take some simple and cheap precautions:

    1. GOOD smoke detector by the boiler, that also signals in your bedrooms
    2. Roxul "rotten cotton" insulation in the ceiling above the boiler
    3. 5/8" drywall the ceiling above the boiler

    Those 3 things would buy you A LONG time in the event of a fire to react and get family to safety. The chances are slim, but I understand your paranoia.

    I don't think the cycle timer and storage belong together. When you shut the boiler down at 190F, what is left in the firebox?

    ac
  8. Fred61

    Fred61 Minister of Fire

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    Wow that statement blows my theory out of the water! (another pun) I just can't imaging getting condensation at full burn. I wonder if it's condensing in the swirl chamber too.
  9. Fred61

    Fred61 Minister of Fire

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    Starting a new gassification session from idle. That's why I suggested that 120 seconds may be too long. I would think that just opening the damper a crack and letting in a whisp of air would maintain a glowing ember somewhere in that bed of coals.
  10. jdkinohio

    jdkinohio Member

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    I usually try to have enough fuel left in the chamber to enable the restart the next day. I typically crumple a few newspapers and light. The remaining wood re-lights immediately. Once it's burning hot, I then open the door and load to about the 1/3 of the chamber (E140), which is about all I can get in there without removing that hanging metal smoke deflector plate. I will add two or three small unsplit branches towards the end of the burn (3-5" dia seem to work great at this point) to keep the fire hot and provide that next night's fuel to start. I can tell how many I need to add by the supply and return temps on the tank.

    I've not seen any evidence of condensation water anywhere around the boiler, other than the ash pan. When I had the motor/fan assy off the back prior to firing this year, it was very clean.

    The garage ceiling is finished with drywall, plus I have screwed a piece of Backer-Board (the concrete board you put under floor tile) to the ceiling that surrounds the point where the black pipe connects to the ceiling connector and where any heat may rise from the stretch of black pipe. I have a smoke detector pretty close to the boiler....probably too close!! I know the WG doesn't load the stack with creosote and is a whole different thing, but I've had too many friends that have had chimney fires, and even one that had a home burnt down. These are all wood stove and fireplace related of course.

    When I leave for work in the morning, the boiler water temp (on top) is still close to 190f. After I shut down, I run the boiler to tank pump on a timer that will keep circulating for up to an hour longer. If I don't do this, the boiler water temp will continue to rise until the chamber fire has gone out. I notice that the return from the bottom of the tank is not up to 190f when the limit shuts the boiler down. It's usually about 185f. Continuing the pump for a while will keep the boiler from getting too hot, plus will even out the return to temp to 190f.

    This routine has been perfect for me....except for the condensation issue, which is more of an annoyance at this point.
  11. avc8130

    avc8130 Minister of Fire

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    I still have the smoke flap in my 180 also. A LOT of wood fits in this thing without getting in the way of the flap. Your firebox is claimed 10 cu ft, mine is claimed 14.

    Have you ever tried burning until there are no coals or anything left? I wonder if you are creating condensation from the remaining wood charge drying out. Starting a fire in the WG is so simple with the huge forced draft, it wouldn't be that bad to have no coals.

    ac
  12. Bob Rohr

    Bob Rohr Minister of Fire

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  13. Bob Rohr

    Bob Rohr Minister of Fire

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    A smoke detector is an excellent addition. I feel a quality CO detector should be a requirement on all solid fueled equipment mounted in a living space.
  14. jdkinohio

    jdkinohio Member

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    I did that the first year and found that it's much easier to keep a little leftover. It's not hard to start a fire, but then I'd need to keep plenty of kindling around to get it going. I think the wood is well dried by the time it shuts down....at least I think it is! I'm going to work on the modification to the black pipe this weekend. Will see how that goes.
  15. avc8130

    avc8130 Minister of Fire

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    Kindling? What's that? All I have ever used to start my Wood Gun is full splits and a few pieces of cardboard...usually from a 6 pack or 12 pack of beer.

    Are you SURE your wood is seasoned?

    ac
  16. jdkinohio

    jdkinohio Member

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    hmmm. I maybe it's the beer part I'm missing! This could be a new excuse to buy more beer.

    I have a moisture meter I use in the wood shop that I use to check the content. I've made a fresh split and the most "unseasoned" wood is about 20%, which is well within what AHS recommends. Maybe for the way I'm buring that doesn't really apply? I have burned less mc and seem to have the same results, condensation wise. The 20% wood doesn't have any problem igniting and burning hot. The only time I see what appears to be a vapor coming from the stack is on cold mornings at initial starting. It quickly burns out any moisture and is pretty clear of any visible smoke.
  17. jdkinohio

    jdkinohio Member

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    ac - Do you gauge wood moisture on time or content? Most probably use time as the determining factor, which I do too, but since I have the meter, what the heck!
  18. Fred61

    Fred61 Minister of Fire

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    Do you Wood Gunners have return temperature protection? ie. Danfoss, etc.
    I was thinking, if you don't the return water could be cool enough to condense in the swirl chamber or beyond. If you do have return protection, perhaps increasing the temperature would reduce condensation.
  19. avc8130

    avc8130 Minister of Fire

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    Interesting thought. I do not have return water temp compensation. My supply and return are 1-1/4". Could I add a Danfoss of smaller diameter?

    I spoke at length with AHS/WG about return water protection. They were insistent that it wasn't needed since the boiler is SS. Then I read through the manual after I bought it, there is one line in there that states "Provision should be made to provide return water temp at 140F" or something like that.

    I'll stick my head in the swirl chamber and take a look.

    ac
  20. Fred61

    Fred61 Minister of Fire

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    How you gonna do that? You have to remove the fan to access the swirl chamber, don't you?
    In this case, the return protection is not because of corrosion. It's just to get rid of the stinky mud.
  21. jdkinohio

    jdkinohio Member

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    That would be quite a trick!!

    I do have a Danfoss valve on mine, and it's 1.5" dia too. I think it's 140f, but if I had it to do over again, I'd probably go with the 160f one. I think that was the other option. You can open up and swap it like an auto thermostat, but I don't think it's quite as easy as it sounds. I could be wrong. At first I thought it could be changed from the bottom of the valve without anything disconnected, but I think it's removed from the boiler side (or top) of the valve. Will have to go look at the pics again, but I "think" that's the way. I'd love to hear that I'm wrong though. Anyone ever change out the thermostat?

    ....I did look up the specs and Danfoss recommends 140f on the return side (which is what I have) or 160f on supply. I guess I'll leave it for a while.
  22. Fred61

    Fred61 Minister of Fire

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    Don't know if the Danfoss design has changed in the last few years but it's fairly easy to change the thermostat on the one I have. Just close your isolation valves if you remembered to install them and remove the plate that is bolted on the side. Thermostat is held in place with a spring. Take a close look at it and make a mental drawing. A little swearing may occur at this point in the operation. The closer it is to the floor, the more swearing will be produced. I know this first hand.
    I would try a higher temperature thermostat.
  23. jdkinohio

    jdkinohio Member

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    This probably what you're talking about. This is actually the pic from New Horizon, where I got mine, and I thought the same valve. Maybe I got an "older" model. Mine does not have that side plate.

    [​IMG]
  24. You probably have the 511 then. Even easier to change, just unscrew the brass plug on the bottom of the valve and the tsat just drops out.

    http://www.danfoss.com/North_Americ...511/ee5d19e5-62f8-42a7-bc0d-0f8ad81164e7.html
  25. avc8130

    avc8130 Minister of Fire

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