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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. goodwood

    goodwood Member

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    my boiler was installed with a danfoss mixing valve [vrg 130] it seems to keep return temperature close to 140 ,i know by pass valves are recomended . are mixing valves acceptable or should i replace with the by pass

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  2. Gasifier

    Gasifier Minister of Fire

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    How close is close? :lol: Your interpretation may be different than someone elses! :lol: No, seriously. I would think that it would be okay. But someone with more knowledge than I will chime in, I am sure. There are a lot of them. :lol: How do you like your boiler? Have a good night goodwood.
    Tennman likes this.
  3. goodwood

    goodwood Member

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    my boilers great its a biomass i've been heating my house for 30 years with a wood boiler, its never been warmer
  4. Gasifier

    Gasifier Minister of Fire

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    Saweeeet. How long you had the Bio?
  5. goodwood

    goodwood Member

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    6 months how do you like the woodgun i've heard a lot of good things abut them too
  6. Gasifier

    Gasifier Minister of Fire

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    Love it. No problems with the boiler. The only problem I have is my chimney problem. My chimney is pretty tall, 27 feet. And my stack temps with the gassifier are lower than they were when I was burning through my wood stove. So now I have a condensation problem. This leads to creosote. My chimney was so clean before. Now it is not. Well. It is right now. Since I just had it cleaned. :mad: I don't like my chimney like that. >:-( Not one bit. I guess I need to try what another wood gun owner suggested and insulate the piece of pipe from my boiler to my s.s double wall, insulated chimney. And hope that increases my chimney temp. and keep things dry way up the chimney. I don't know.
    goosegunner likes this.
  7. jdkinohio

    jdkinohio Member

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    At the risk of replying to an old post.....I'm curious if you have solved, or limited your condensation issues.

    I have an E140 that is in the 3rd year of use. I use an insulated 500gal of storage. I am very pleased with the efficiency of the unit and warmth it provides, but I can't seem to get past this condensation problem. It's not extreme, but I do notice water, or at least evidence that there has been some moisture in the ash pan. The ashes are more caked together. My guess is that condensation is coming back from the pipe and dripping through the cyclone straight into the pan.

    Operation is typically once a day. The boiler water is normally around 150f-160f when I get home from work. The refractory is still very hot and aids to restart fire without any problem. Once the fire is going, I'll load the chamber to maybe 1/2 full. It doesn't take much more than that to get the storage tank back to 190f. I try to shut off (or let the limit shut it off) with just a small amount of wood remaining to use to restart the next night. Prior to starting the next cycle, I always check the ash pan. Not much is in it, but I usually see a spot in the middle (maybe only the size of a dime) where the condensation has dripped. There have been times where it's worse.

    I have black pipe connected to the cyclone, which extends upwards to an elbow, then approx 8' to another elbow that connects to the ceiling connection. From there, it goes through the house and roof. Probably total length from ceiling connection to top of stack would be 20' max. This would be a combined stack length of close to 30'. The tech guy at WG didn't feel this would be an issue, but I'm suspicious. The boiler is in a garage, under the house, which stays very warm all the time. I wouldn't think the uninsulated black pipe would cool enough to condense, but maybe so.

    Enough rambling. Would like to hear how yours is getting along.

    thanks
  8. Gasifier

    Gasifier Minister of Fire

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    Mine is getting along much better. I switched the single wall pipe over to insulated, double wall stainless pipe. I come out of the ash cyclone with single wall for about 12-14 inches and then transition to the insulated pipe. This has all but eliminated my problem. Along with that I am also burning wood that is seasoned longer than last years wood. I believe some of my problems was from the pipe losing a lot of heat inside and maybe some wood with higher moisture content than it should have been. I do not think it matters how warm the area where your boiler is. The single wall pipe is still going to lose heat that radiates off from it. With the lower stack temps that the gassers put out it seemed to create a problem for me because of my long chimney. I had about 12ft or so of single wall pipe inside and then another 27 feet of insulated through the wall and up the side of the house. Now I have 12-14 inches of single wall and the rest is insulated. You have a similar amount of chimney.

    How is the moisture content of your wood?
  9. Gasifier

    Gasifier Minister of Fire

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    jdkinohio. You said operation is typically once a day. When do you have to start burning more often when it really starts to get cold? I see it is high 20s at night where you are now. How often do you have to burn if it is zero out? How much sq.ft. are you heating?
  10. jdkinohio

    jdkinohio Member

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    I've split a piece to check moisture content in the center of the wood, and it measures 20%. I have more wood that's probably closer to 10%. I could burn a load with it to do a test. According to WG's user's manual, 20% is well within the recommended MC. I'm afraid the pipe is the issue, and I'm really not thrilled about buying new pipe! I guess you do what you have to do if that will correct the issue.
  11. Gasifier

    Gasifier Minister of Fire

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    I have forgotten who did it, but you can also insulate your existing pipe. That would be much cheaper. Who was that?
  12. jdkinohio

    jdkinohio Member

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    Morning's have been in the twenties for the last couple weeks, but daytime highs have been pretty nice. I actually ran the first load and brought the tank up to temp on 11/17. It's been so warm, the gas furnace has hardly worked, so I couldn't get myself to start burning wood yet. I do have a separate wood shop that's heated by a small gas boiler, and I did turn that on a month ago!!

    Although zero is not real common here, it can happen. When it consistently gets below freezing, if the wife will be home for the day, I'll put in some wood and fire it up before I leave for work. She will keep an eye on it and shut down when needed. If I don't fire it before I leave, the tank will be down to 130f-140f when I get home, which of course then takes more energy to heat back up. I like to not get below 150f, but it does happen in colder temps.

    I'm heating about 1800sf. Kids are all gone, so the registers in a couple of the rooms are choked back a bit, but it's comfortable throughout. We've always cut the temp back at bedtime to 66f, so that conserves some. It kicks back up before I get out of bed in the morning. We keep the temp around 68-69 during the day.


    Now that I've said all this, we'll probably have the coldest winter in Ohio history!! (bring it on!!)
  13. jdkinohio

    jdkinohio Member

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    I wondered if that was a possibility.
  14. jdkinohio

    jdkinohio Member

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    but I don't think it is.
  15. jdkinohio

    jdkinohio Member

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    I did buy some fiberglass "pipe wrap" with foil backing. Supposed to work with steam pipes, etc., so I thought I'd give it a try. Smoke detector near boiler seems to go off at the thought of opening the loading door, so I figure it will alert me to anything nasty happening with the wrap. I didn't wrap the vertical pipe coming out of the cyclone, only where it turned and ran about 7' somewhat horizontal towards where it turns again and connects to ceiling triple wall. The pipe temps seemed to get a little higher. When the boiler shut off (hit limit, which is what I usually let happen), I waited a half hour or so, then took the ash pan out. It was dry and had a small amount of ash. Put a metal pie pan in the tray under the cyclone opening and checked an hour or two later. Small amount of water. Very small. Put back in and checked when heading for work the next morning. What was there evaporated and no sign of any more.

    Will have to investigate a better method of insulating. Still don't want to replace with insulated stove pipe. I'm sure nothing would fit the same, and I don't think you can cut those interlocking sections, like I think I did on a chunk of black pipe.

    Also, one note on the door smoke. I've seen posts on the smoke hood, etc.. When I want to open door and throw in a few more pieces of wood, if it's excessively smoky in there, I'll turn the damper on the intake to close, then open door. The air is then drawn through the front door and keeps the smoke in. This has worked great for me. You just have to make sure you remember to open damper after you shut door!!!
  16. jdkinohio

    jdkinohio Member

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    Did the pan thing again last night and check this morning. A lot more water today. Temps last night were about 20f, so this must have contributed to more condensation. I'm beginning to think I need to get used to it.
  17. avc8130

    avc8130 Minister of Fire

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    I have damp ashes also. I have found my ash drawer full of water like a swimming pool also.

    My chimney connector is double wall pipe.

    I don't know what causes it either. That water sure is stinky!

    ac
  18. Fred61

    Fred61 Minister of Fire

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    Got any Idea how many times your boiler goes into idle over the course of a burn? I always suspected I was accumulating water when the fire re-kindles. Even though the Wood Gun quickly brings the fire up with it's high airflow, there is still a fair amount of time that the fire is cold, giving it more of a chance to condense in the flue. I doubt that it is condensing at full burn. Storage would help with longer, hotter burns but even if your wood is very low in moisture, water is a byproduct of combustion and getting it out while it's still vapor is the goal.
    Taylor Sutherland likes this.
  19. avc8130

    avc8130 Minister of Fire

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    This is one of the main reasons I think the cycle timer is a good idea. It helps to keep the flue temp up as well as the refractory hot.

    ac
  20. Fred61

    Fred61 Minister of Fire

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    That won't be enough. Basically your cycle timer will keep your coals glowing enough to re-kindle your fire but won't do much to warm up your refractory. It wouldn't get hot enough anyway to keep the flue at a high enough temperature to stop condensation. You don't want your cycle timer to operate the fan long enough to start gassing otherwise you could end up in overheat.
    Taylor Sutherland likes this.
  21. avc8130

    avc8130 Minister of Fire

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    The cycle timer will do whatever I tell it to.

    I have had the boiler on the high limit a few times. It is going to happen if you use the cycle timer. The high temp aquastat is the main control. NOTHING else can happen if the high temp is over limit.


    ac
  22. Fred61

    Fred61 Minister of Fire

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    Well it looks like you have it pretty much figured out.
  23. avc8130

    avc8130 Minister of Fire

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    Not in the least. I was speaking tongue in cheek, but did a poor job conveying that. Sorry.

    I'm still learning.

    I do think running the boiler on a regular basis has made the situation better overall.

    I have a much better coal base, less condensation, and haven't lost a fire.

    ac
  24. Fred61

    Fred61 Minister of Fire

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    No need to apologize.
    As the winter progresses and temps drop, your boiler will run more and you should get less condensation. Really, your Wood Gun doesn't need much glowing charcoal to re-kindle. A glowing coal the size of a pin head will re-light the fire. Keeping your boiler hot with the timer will only prolong the idle time causing more nasties in the fire box and flue.
    It didn't occur to me that the cycle timer was limited by the high temp aquastat. Makes sense as opposed to a sticking cycle timer that is free to spin the blower at any time. I never had a cycle timer on mine.
    EDIT: More frequent and shorter cycles should be better than few longer ones.
  25. avc8130

    avc8130 Minister of Fire

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    Fred,

    Your "edit" is exactly what I was going for. I tried to set the timer often/long enough to try to get a good, clean burn. 6 mins/hour has the fire rocking pretty good. I tried 4/hour, but lost the fire one day. At 6 I haven't lost it since.

    ac

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