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Garn is up and running

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by curtis, Jan 4, 2014.

  1. curtis

    curtis Member

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    Was able to fill my garn 1500 today and get the new controller wired up. I started a fire about an hour ago and the tank temp is slowly rising. Everything went together great with the exception of one copper union in the house that just won't seal.

    I had some water leaking out the back of the flue but I think that was just because the water was only 45 degrees. I'm glad I can shut off the oil furnace and heat my house with the garn the rest of the year. I've got about 6 cords of ash stacked up ready to burn.
    heaterman and hobbyheater like this.

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  2. BoilerBob

    BoilerBob Member

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    Awesome, Congrats

    Got pics of first fire?
  3. curtis

    curtis Member

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  4. kjahnz

    kjahnz Member

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    congratulations on your first fire. that fire box is HUGE. the water leaking, maybe from the moisture your cooking out of your refractory. seems like your timing is pretty good also, gonna get cold the next few days.:ZZZ
    hobbyheater likes this.
  5. curtis

    curtis Member

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    Ya the moisture from the flue is now gone. I just read in the manual that if the water temp is low like mine was there will be condensation in the flue.

    So far my tank temp is 155 and my supply temp is 119. Will it take awhile for all the water in the tank to equalize in temperature?

    Also the difference between the supply and return temp at the garn is only 2-3 degrees. Granted that's with no load on it but I thought for a 200+ ft loop that that's pretty good. I used 1.25 rehau insulated pex.
  6. kjahnz

    kjahnz Member

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    I don't have a garn, wish I did. Happy heating.
  7. bpirger

    bpirger Minister of Fire

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    Congrats! First fire in our 1500 on 17NOV2010...and not a drop of oil burned since then. We are pleased with our Garn.

    Search through for Garn threads on temperature stratification....all sorts of things you will get used to. Where are you measuring the 119 supply temp? All depends on your HX and everything else.

    We have radiant heat and also heat our DHW. We can use water temps down to about 100-110 to heat the radiant (depends on the temp outside) but for DHW needs to be 120ish.

    I have an 80 plate HX and I'll measure about a 20-25 degree temp difference between the tank display and my supply in the house....many hours (12-16) after a burn. Right after a burn they will be much closer. Someday I will have to install my temp sensors everywhere and then I will really understand just what is going on. Past measurements showed me that I was within a degree or two on either side of the HX. I wanted to be sure I could use the water down to the 100 degree range. I'm pretty sure the actual supply water temp can vary significantly from what the tank temp display says....despite the level of the supply line and thermo wells being rather close.

    My only other comment is that the target temp for the Garn tank is supposed to be 190 according to Dectra. Higher temps apparently will speed up the breakdown of the tank chemistry. I have never measured the bottom, middle, and displayed tank temp (near the top), but after many hours, there is quite a stratification built up. You can easily feel it with your hand....
    hobbyheater likes this.
  8. curtis

    curtis Member

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    Well I went to bed with the tank temp reading 190 and just a small bit if wood left in the firebox. Went out to check it just now and the tank temp is reading 174. Kept the house at 71 all night. The copper union must have sealed itself up once it got warm water running through it. Everything seems to be working great on it so far.

    When judging wether or not to do another burn, do you guys go by the tank temp sensor or the supply temp? I have my supply temp sensor mounted on black iron pipe about 6" from the garn itself.
    hobbyheater likes this.
  9. Robert V

    Robert V New Member

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    I have only been running my garn 2000 this season but I quit paying attention to the tank temp as it never matches the supply temp except after a full burn.. The way I see it the water going to my house is what matters. The garn seems to leave a level of hot water at the top of the tank all the time. I think it is because the water outlet is aprox a foot lower then the actual water level so I think the top layer of water never really gets used. On the other hand perhaps this helps keep the water under it warm. Any one else ever notice this?
  10. curtis

    curtis Member

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    So do you burn until your supply is 180-190? What does your tank temp read when you do that then? I just don't want to boil my water in the garn by over firing.
  11. Robert V

    Robert V New Member

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    The two temps will just about match after a burn. My goal temp is 190. Usually it will say the tank temp is about 195 and supply temp 190. Of course its not perfect every time but I am sure I will get better with time. I did boil mine once and it pushed water out the overflow all over my floor. Over all I am super happy with it so far. I only burn it once per day and it usually goes 3 to 4 hours. One thing I am wondering is why my flue temps are so high. I am burning decent dry hardwood mixed with some dry soft wood and my temps during a full burn with 135 deg ish water run 400 to 450 deg. Sometimes it will peak just over 500 on a hot load. I would like to here from experienced garn owners if this is normal. I super cleaned all the tubes, passages, wheel, ect before the season.

    Curtis,
    Your running a air/water HX in your furnace right? I am running panel rads on the main floor and a air/Water HX in the basement. I have found that the air/Water HX runs non stop when the water temp drops below 130 ish.
  12. curtis

    curtis Member

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    Just got done with a burn and the tank temp is 184, the supply is 160. They never seem to get much closer than that. Idk if the sensors are reading right or not.
  13. TCaldwell

    TCaldwell Minister of Fire

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    Robert, for the wood you are burning those flue temps would be '' normal'', if you are not puffing your wood is very good. If you are puffing add some larger splits or a few pieces of higher moisture % wood.
  14. Robert V

    Robert V New Member

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    The supply/return temp sensors are strapped to the pipes right at the garn? Do you have any other temp sensors other then the garn controller? Are you still on your first couple burns? I wonder if your just getting tank stratification. Mine did some strange things on the first few burns. Does your garn water circulate constantly?
  15. curtis

    curtis Member

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    Yes they are strapped onto the black pipe that's connected to the garn, about 6" from the boiler. I only have one other mechanical temp sensor in the return and it reads about 170.

    Yea today is my second day operating the boiler, fired it last nite for the first time and today was the second fire I had in it.
  16. Robert V

    Robert V New Member

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    Caldwell,
    Ok that's cool I did get some puffing early in the season when I was first getting to know it but none now. It seems to pick up temp quick so I figured the tubes were not coated too bad. Is 3-4 hours a normal burn time to climb from 120 to 190?
  17. curtis

    curtis Member

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    Oh and I have another question for you guys. Did you silicone and screw the exhaust pipe to the boiler? I haven't and it seemed it would make it a pain to take off if you ever had too.
  18. Robert V

    Robert V New Member

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    Well something doesn't add up. If the garn control says you have 160 going out but your mechanical gauge says 170 coming back then something is not telling the truth. Does the garn return temp on the controller match the analog? You might just want to give it a few more burns to let all the water come up to temp. Have you done the old touch/feel the pipes trick?
  19. curtis

    curtis Member

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    The mechanical gauge is reading about 10 degrees warmer than the electric gauge on the controller. I'm going to get a couple strap-on thermometers and see what those are reading.
  20. sjfrench

    sjfrench New Member

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    Reading your thread is like living my last month all over again. We just fired our Garn in mid-December. Love it. I've got a ton to learn, but here's what I'm experiencing so far:

    1. Definitely seal that exhaust with silicone. I missed that in the manual on the initial install and had liquid black soot slowly seeping out of the exhaust into the building. I did the silicone it and it was fixed instantly. It also cut back on some smoke that seemed to be infiltrating the building. I thought it was the door because of all the puffing, but most of it was the silicone.
    2. My system was puffing like crazy. Went back and read the manual again and I put some scrap boards at the very front entrance by the door, I just left a small gap between the door and the wood. Solved it instantly. Never had another problem. I was just loading it too full, clear up next to the door entry. The manual says we can also use a firebrick.
    3. I now watch both the supply temp and the tank temp to determine the next burn. For the first two weeks, I did as the earlier poster mentioned and just watched supply temp. And then last night, I had some serious stratification taking place in the tank and didn't realize it. The tank was in the high 180's, the supply was in the high 160's. I knew it was going to be very cold, all four pumps were running, so loaded up and fired. Went out this morning and the five gallon bucket I've got below the overflow valve was halfway full. Crap. That's the first time I've ever had water come out of that overflow, including the initial firing. So I did a ton of reading all day during the NFL games and I've decided not to fire if the tank temp is above 175. There is a very helpful post about the possibility of corrosion when the tank gets fired above 190 - http://www.hearth.com/talk/threads/my-garn-corrosion-fiasco-part-1.64261/ I don't think I'll be doing that again.
    4. My readings on my supply and return sensors changed instantly when I wrapped them in insulation.
    5. Some R-30 insulation goes a long way. I super insulated the underground with sprayed in closed foam...but left some pipe exposed when I went through the crawl space under the house. Figured it was like having radiant floor heat. I went back and insulated those supply and return pipes and it has made a huge difference in how long my tank holds temp.
    TCaldwell likes this.
  21. bpirger

    bpirger Minister of Fire

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    That all sounds right on course to me! I watch primarily the supply temp in the house, since the tank temp is outside, to determine when to fire. But I never fire unless the tank temp is down about 120. One thing I will do, I have all radiant, is drain the heat out of the Garn until the supply is about 115 or so....then fire. I've also come to crank up the thermostat temp while I am burning, if it is cold outside, to "supercharge" the enormous concrete slab. The floor will get up to about 83F or so, it feels incredible when it is 0F outside, and the air temp about 74-75. We have a lot of glass and when the temp is that cold outside, it is great. I won't call for more heat then until 12 hours or so later, setting tstat back to 72. I use this really only when it is very cold outside, less than 20F.

    I heat DHW as well, which is the really what determines when we fire. I set my controller (sensor in the indirect and system controlled by Tekmar 363 is it?) for DHW at 115. So I can reach that point when the supply is 120 or above. Sometimes (like this evening) the DHW will run for hours if the supply is at 119, the indirect at 118, as it turns off when it reaches set point plus 4. So quite seriously, the need for DHW will drive when I fire. I can heat just fine down to 100-110 on the supply. I have considered some kind of DHW "supplement" which would kick in when the supply is below 120, just to get that much more heat from a single fire, and burn a little less wood. Though we only burn about 6 cord a year....2500 sqft, lots of glass, all radiant. When the addition comes online (another 1000 sqft) and if ever I connect the big garage/shop (2200 sqft), all radiant slab, then my load will increase a bit.

    I also am still running my initial "non ideal" buried lines for part of the underground and I know I am losing there. Long story....short version is when I built the house in 2001 I placed the oil boiler outside in its own shed and brought the hot water undeerground via 1" hepex wrapped with foam "pipe insulation" inside a 4" conduit. I am STILL losing here for sure. One of these days I have to connect the addition (still unfinished....the eternally DIYer here) to the system and will use the new 1.25" microflex buried lines. I think that will save me considerably, perhaps as much as the load on the addition.

    One thing I notice is that my high temp (the 180's right after firing) don't last very long. Within a couple of hours I am down to the 150's. I think that is the crappy buried lines. But once I hit the low 150's it will persist for quite a long time. Once I get down to the 120's....I have many hours left. Higher temp differential, bigger loss. For all I know my 4" conduit could be filled with water.

    I wouldn't fire with anything more than 145 or so, but I also don't need the higher temps. With the baseboard or air-water HX, and the need for higher temps, I suspect you'd have to burn sooner. I know I always recommend the Garn for radiant but tend to dis-recommend for air HX or baseboard unless the coil or lengths of baseboard is massively over designed to work with lower temps. It just seems to me that the system wouldn't last very long (i.e. not one fire a day) if I had to have 140 minimum water temp. At that point, to me, one of the other boilers with storage would be likely better....I have the perception you keep those fires going longer. More frequent feeding the monster, but more consistently higher temps.

    The only place I have seen water creepage from the flue is the coverplates just below the draft motor, and only on the first fire from 70F tank or so. After that, not again. I did put silicon around the chimney on the rear....I believed I DID screw the insulated flue onto the flange on the rear BEFORE I built the box around the unit. I boxed off around the pipe to hold back all the fiberglass. Yes, it will be a pain to get access to the screws if I need to remove.

    You can really tell when you need to clean your flue tubes by looking at the exhaust temps. Generally the flue temp will be right around 500, just a touch higher. But as time goes on, it will begin to creep up. Time to clean. When I cleaned this late fall, I was getting up to about 600F at the flue, as it had been about 14 months or so since I cleaned. After cleaning, it dropped right back down to the 480-500 range. I just use the brush and rods and spend about 15 minutes scrubbing each of the 4 lines. I got a fair amount of soot out....maybe 4 cups total. I shouldn't let it go so long, but was busy hanging log siding all summer.

    We do burn all year round for DHW. In the summer, I fire about once every 4-5 days. Household of 5, at least 7 showers a day, two loads of laundry, etc. I will try and burn "crappy" wood then if I can, i.e. pine I drag in or similar. "Free" DHW heat.

    Puffing issues will be had when you use smaller splits, or lots of lumber scraps, or say a pile of white pine log siding scraps! It is quite an event when it happens, as I swear it feels like the door is going to blow open. In fact, with my too large of a load of log siding scraps, I actually had a little puffing out of the left bottom flue cover, after I cleaned it out. Tightened the nuts a little more...no more. I have only seen puffing a few times though....literally 3 or 4 since 2010. Each time I knew it was likely to happen. SO just think about what you are putting in the beast.

    Regarding the firebrick in front of the air supply. What I have noticed is that to get a clean burn, i.e. no smoke visible coming out the flue, I need to place something here to deflect some air upwards so that all the O2 isn't consumed in the firebox itself. My wood is just under 24", limited by my splitter stroke length, so I try and build the fire aways back intot he chamber. Then after it is going, say a few minutes into the burn when I am sure it is cranking, I will place a small chunck in front of the stack. This really seems to clean up the burn every time. I usually use those small end pieces that one always has laying around. I did cut some "cookies" before about 2-3" thick when broken in half make an ideal piece for this. They burn up of course, and I don't have to remember to pull the brick out, or not bury it, or drop wood on it, etc.

    One last tidbit. I have the sensor that the controller uses in a well and also another sensor in another controller in another well. These two sensors will be about 10F off from each other! I suspct it has to do with the contact of the sensor in the well....I am willing to bet one has grease and one not...etc....but i haven't really ever looked into it. One of these days, one of the projects is to install the 32 one-wire temp sensors every where and watch what is going on. But that will only want to make me build a system controller that I can finely tune everything! I like the Tekmars, but I sure wish I could variable speed all my pumps to only bring in exactly what I need from othe Garn, get rid of some time delays it appears to have, etc.

    All in all, we are very pleased. I run through about 2 Mg rods a year. Don't understand why this is since the water chemistry has been great. Make sure you send out samples every six months to Mike at Precision. Since 2010, I only had to put in one bucket of stuff, about $80 or so, plus a rod every six months! They do add up from Dectra. Must be an electrolsys issue, but I have my pipes grounded, not sure what more I can do.

    It is quite amazing how clear the water stays inside the Garn. Take some time and inspect it when you get your sample every six months. I have yet to see anything that I think is a problem. The flues and firebox will get a white scale on them, presumably from the additives, but this is normal. After my first flue cleaning and I looked inside, some of the scale had broken off and was floating on the surface. That's the only thing I have seen besides clear water in this thing.

    As long as there are no corrosion issues, I assume this thing will last a very long time. Rick's issues (linked to above in another post) were related to bacteria. On a chicken farm, I can imagine this is much more likely than in a homeowner environment. I would be really bumming if that happened....but Rick has also stated that he feels like it was his fault for not sampling water directly from the Garn itself. Hopefully things will continue smoothly.

    For us, with radiant, I don't think there's a better way. I only wish I had sprung for the 2000 instead of the 1500....but it is rather rare that I fire more often than 24 hours anyways....so not a real issue at all. I do think the numbers are a little more efficient. Must get the final exhaust temp a little lower since there is more surface area in the longer flue length (I am assuming) in the extra 500 gallon volume.

    OK, exhausts my Garn learning tidbits. It's been bulletproof operationally....I don't think it could possibly be easier.

    One more....I find that when I put the manhole cover back on, the gasket there will fall apart after just a few opening/closing. I only look inside once every six months, but I essentially plan to replace the gasket every 12-18 months. I have done it once...I need to do it now I think. If you get a little opening, you will get some steam release, and your water level will drop accordingly. Takes some time...but it will happen. I took off the old one, used a hand grinder and sand paper to clean up the lid, and put on the new one. Tight as can be. Just something else to think about.

    There WILL be some "sparks" and little chunks blowing out the exhaust at the rear....so keep this in mind. Don't let the grass turn brown and dry where the exhaust goes. Another member here with the vertical chimney has some concerns with embers blowing up and out....not sure what his final outcome was. But if you sit outside and watch during a night burn, you will see them fly out. The 90 into the garbage can likely will solve that issue totally as well. My 90 usually falls off and I vent outwards....oh what a screw can do here, eh?

    Way too long. Enjoy! I remember my excitement/apprehension when I was looking to buy/did the installation. Couldn't be happier at this point....our fourth heating season. Not a drop of oil since Nov 17, 2010!
  22. Sawyer

    Sawyer Minister of Fire

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    Well said Bruce and others! Curtis, you have been given some excellent information and advice. Bruce’s firing practices and flue temperatures are the same as mine however my anode rods are still original. I see you are located in the UP, not sure how far you are from Wakefield but I am just south over the border a mile and a half.

    I have the old system controller and do not have the auto shutoff. I fire when my Garn is at least below 150 degrees and preferably 130* to satisfy DHW. I heat 6,000 sq./ft of living space. I have a combination mostly radiant/HX coil system. I may add panel radiators this spring as it solve my extreme heat loss problems in the living room. If I do this the air handler would hardly run.

    I have calibrated all my thermometers in boiling water; this helped some of my temperature questions. I ignore the probe in the front bung. The thermometer in the flue seems to almost match the supply temperature after the Garn is shut down for a while. I can tell weather to fire or not just by viewing it when I enter the boiler room. I use a infrared gun to check supply/return temperatures. It seems to give rather accurate readings on a black dishcloth in boiling water. I have painted sections of pipe as well as spots on the air handler to produce accurate readings with the gun. I am not as much worried about the exact temperature to a degree or two as I am knowing the same instrument is doing both measurements so the temperature differences should be accurate.
  23. RowCropRenegade

    RowCropRenegade Feeling the Heat

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    Sounds like all you guys are getting along well with your Garn. I love mine but I absolutely HATE my house and it's use of the heat. When it is below 15 degrees, I can only go 5-6 hours in between burns. And that is charging the unit to 205 degrees. You don't replace burning 2000 gals of fuel without burning some wood!
    curtis likes this.
  24. Sawyer

    Sawyer Minister of Fire

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    I hear you Reed, we have warmed up to -22 at present, it will take two full burns for 24 hours. I would much rather burn 300# of wood than the equivalent in LP. I had a trouble call at 2am, -27*, when a LP furnace didn't want to burn LP either. :)
    RowCropRenegade likes this.
  25. jebatty

    jebatty Minister of Fire

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    This is the nemesis affecting all hot water boiler systems that require high temperature water. A gasification boiler with storage is not immune to this problem but boiler sizing and proper plumbing and system design can alleviate some of the problem. If 170F or hotter water is required, a Garn or another gasification boiler may need to burn almost continually to meet demand. The primary difference lies in how much water the boiler needs to heat before the 170F+ water is available to the system.

    With a Garn the boiler may need to heat the entire water volume before the high temperature water is available if the system is calling for heat during the burn and there is substantial mixing in the Garn during the burn. That's 1000 gallons of water and up, and that may take awhile before the hot water is available. Once the hot water is available, the hot water can be maintained by constant burning as needed, if the burn available btu's equals or exceeds demand. But there is a potential issue with a Garn that is burned continuously, and that is ash and coal buildup that at some point needs to be removed, perhaps even daily. The Garn's design is best for batch burn operations, not continuous burn, when the Garn can allow the coals to burn out and the ash removed between burns. And a batch burn operation with high demand then may result in the water volume cooling substantially below the 170F+ needed temperature.

    With a gasification boiler with storage, during a burn the boiler only needs to heat the water content in the boiler to the needed temperature, a volume roughly in the 50-70 gallon range, and there may be only a small delay until this temperature is reached and the boiler is satisfying high temperature system demand. Any excess btu's not needed to meet demand can go to storage, and it is not necessary to heat the entire storage to the 170F+ water before water at that temperature is available to the system. Of course, the boiler also may need to be burned continuously to meet the high temperature demand unless its btu output exceeds demand, in which case the excess goes to storage. And ash and coal buildup is not normally an issue with these other gasification boilers as they can be operated days and even weeks at a time without any ash removal and in my experience there is no coal buildup, and if ashes need to removed they can be removed easily with little or no interruption in the burning. A gasification boiler with storage also provides performance and advantages similar to the Garn in batch burn operation, which is how many users enjoy their systems: heat the storage up to 190F or so and then draw from storage until the boiler needs to be fired again. For gasification boilers with storage, there is flexibility is sizing the storage based on desgn need and/or space available, but storage ranging into the sizes of Garn vessel size likely would be desirable for similar boiler Btuh capacities.

    Both the Garn and other gasification boilers with storage can provide excellent low temperature service, that is, service where the need for hot water is 140F and below. Both can heat the vessel water volume/storage to a high temperature in a batch burn operation, and then satisfy demand from storage until another burn is needed.

    My direct experience is with a Garn WHS3200 (3200 gallon vessel size), a Wood Gun E500 with 4000 gallon storage, a Froling FHG-50 with 1600 gallons of storage, and a Tarm Solo Plus with 1000 gallons of storage.

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