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Post in 'The Boiler Room - Wood Boilers and Furnaces' started by avc8130, Sep 24, 2012.
In our sand box wood boilers don't idle and forklifts are tractors. AHAHAHAHA
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My honest and naive question to other gasifiers is this:
When your unit has reached it's operating temp and goes into idle, off, slumber or cylcing mode
Does your fan continue to operate or do you continue to exhaust from the stack?
The reason I ask this is because everyone (except WGrs) seem to be worried about creosote in their flues.
Which would occur if the unit was smoldering and allowing that exhaust out into the flue.
I have followed this thread because it's like reading a history of my experiences with my old gun with the worn center bricks, explosions, lost fires, clogged cyclones, leaking flues, muddy ash, hot flues, ash in flues, interfering smoke flap, etc,etc. I have given my opinion as to how some of these problems can be dealt with and what to expect and have met resistance all the way.
There seems to be an awful lot of discussion on these subject, like over 800 entries, for people that don't "give a crap". I'm free from the problems since I am a "FORMER" owner even though it looks like I "REALLY care".
For what it's worth Fred I do appreciate your experience and I actually believe you do care to help us navigate through our new experiences.
My question to you would be does your eko idle or shut down the same way a WG does.
I'm not trying to be a jerk I'm asking an honest question.
I don't think I heard you disagree with us on that regard. But I also suffer from selective memory loss so maybe you have.
My fan slows down progressively to 50 % of its output as the boiler nears the setpoint and then OFF when it reaches the setpoint.
Instead of a motorized damper it uses a weighted metal flap to shut down the only and very small (~ 2" x2") opening. The fire goes OUT! The boiler then cycles on and off. How often is adjustable down to 1 sec every 5 minutes and up to 60 sec every 99 minutes. I have mine set for something like on for 10 sec every 90 minutes. Only to make sure there aren't too many gasses built up in the chamber.
Honestly I have never had mine idle for that long. I try to match the amount of wood to the heat demand I expect. From what I have read here people are concerned that if the boiler is cycling on and off (ideling) then that is when you are making creosote. I am adding storage so I can have fewer fires with more wood in the chamber.
Woodguns strategy of loading it up and then turning it off/on seems contradictory to everything else I have read about efficient wood burning, ie small hot fires with water storage to save the heat for later. But if it works what do I know.
But then again I don't have clogged nozzles, water in my ashes, a smelly basement, back puffing or a clogged cyclone.
Once you get a Gun figured out, and are burning dry wood, with regular cleaning, these issues are gone. And with water storage, it also helps the system be more mellow. No matter what boiler you had in the past, or have now, everyone who has had it, knows that storage is the way to go. I would not hesitate to say that the Wood Gun's efficiency is up there with anyone elses boilers. I heat 4200 sq.ft. house, 900 sq.ft. garage, and DHW for a five member family. Last year I went through about 8 cord of wood. A mild winter though. If it was a cold winter, I could see going through 10 cord. I think that is good. My insulation is good in some places and not so good in others. So averaged out, pretty decent insulation.
My gassifier has no fan, doesn't (can't) idle, and simply burns wide open until the fuel is all gone. If it gets too hot (that would be above, not at, operating temp), it can dump to the house zones - but that hasn't happened yet, the storage has been absorbing all the extra heat.
But about your last two lines - I believe Gasifier made some flue/smoke pipe changes in the off-season (going to all double wall insulated?) because he was getting creosote buildup in his chimney. So doesn't that mean his WG was (still is?) actually smoldering & allowing exhaust out into the flue?
I'm not pro-this or anti-anything - I think we're all basically doing the same thing with a few minor differences that don't amount to a whole lot. Different strokes for different situations & preferences, I'd say.
been following this thread trying to learn as much as i can.
with regards to timers and such, it sounds like you guys could make good use of a time delay relay. with minor motor control knowledge, this timer will start ticking (1 hours, 80 mins, 2 hours, 4 hours, whatever you want) exactly when the unit shuts down due to high temp or no call for heat. it will reset itself (might have to add another relay if you dont get a fancy one) after its own event and that will keep the WG cycling. no problem if there is a call for heat before the timer runs out, the timer relay will just reset again for your predetermined length of time. this way it will not try to turn on due to timer 5 minutes after the heat load is met just because that is what the programmable 24 hour timer is telling it to do. i dont know exactly how you would wire this into your low temp cutoff, but that is for you current WGers to figure out.
This is an interesting idea and probably would avoid the back puff problem entirely. Of course, the best way to avoid this is just what Gas has said...storage! Perhaps one day I'll have the room and $$ to put in storage. In the meantime I would be happy to learn from somebody much smarter than I am to investigate this option.
It is interesting for me to note that all the "items" Fred detailed with the exception of worn nozzle were items I did indeed experience in my first year due in large part to the learning curve, lack of large amount of storage and less than desirable wood. ALL of those issues are now dealt with and history for me. As for the nozzle, is it not something that would be a wear item on any boiler just like tires and brakes are on a car?
Exactly. All of those "issues" appear to go away once the operator is trained.
YES. Nozzle wear occurs on any gassifier. There are many threads about guys rigging up fire brick and other means to extend nozzle life on non-WGs. I plan to make some steel nozzles when my stock cement ones wear out.
My nozzles have never clogged. When I reload I simply use the included tool to rake through the coals and send the ash down through the nozzle.
I plan to bring my air intake outside. This will prevent back-puffing from mattering, and keep the WG from drawing heated air up my chimney. Win/win.
Clogged cyclone? I'll take it. This is by far the easiest way to deal with ashes I have ever seen. A simple drawer where 90% of the ash that matters winds up. Every 3 days I throw 2 clips and dump the pan. I think the only instances of clogged cyclones were from guys getting lazy and waiting weeks.
Smelly basement? Fixed. Poor chimney connector install.
A full reload takes me <3 minutes (I know because I set the purge timer for 3 mins and it is always still running when I walk away). 6 mins/day for heat. Seems pretty easy.
Everybody seems to be satisfied with THEIR modern wood boiler. I don't really understand why there are always arguments and bashing against the WG. The damn thing works. Get the install right, learn how to run it and it is "wood in=heat out". I scoured the forum and I don't see the hatred from non-owners against Econoburn, BMW, Tarm or any of the others. Maybe the WG owners need to go on a crusade. Bashing all of the "fancy" boiler owners and demonizing storage and monitoring.
If I had brought this site up earlier than Mike, my response would have been the same, almost word for word. Our units are similar except one has forced draft and one induced draft. I also match wood to demand and only idle (combustion fan off) for approximatelt 10 minutes when storage temp is approaching maximum. I don't even know what my cycle timer is set at and see no need to even find out. If wood load is matched correctly, there is only a nice thick load of coals that don't produce much nasty stuff that coats the fire box. If I loaded too much wood for demand, I just shut off the boiler master switch and it leaves me with a nice bed of charcoal to start tomorrow's fire. If I didn't load enough wood, I don't add more because storage doesn't need to be at the high setpoint to go 24 hours so I don't push to get every last BTU out of my load. I still shut it down because the left over charcoal in of more value to me than one more degree on the thermometer.
For some reason you're have the misconception that Biomass, EKO, etc are getting creosote in their flues. That could not be further from the fact. There have been posts on here with operators that have experienced the problem but there were other circumstances involved.
The only reason I can see as to why idle, shut off, slumber definations are such an obsession is because that statement in the salesman's pitch is the reason you bought the unit.
A few gunners on here have figured out what's going on and have taken steps to work around the idiosyncrasies of the Wood Gun. Gassifier is one that comes to mind.
I don't think there's hatred against the Wood Gun - I think I've seen it recommended as a boiler choice as much as any other unit here.
I do think there might be some difference of opinion with how WG seems to claim it deals with idling differently than the rest - i.e. relighting from hot refractory - when it seems to be more like they operate more the same as the rest and aren't really that different (some read 'better') - i.e. relighting from a still-burning ember. Maybe they do a better job at keeping the ember going longer - I don't know - but what some might read as hatred towards the WG I'd construe as some defending their own unit against what they feel to be an unfair assessment on different operating principles and implied inferiority.
Did that even make sense?
Although I think that bringing in outside air is a good Idea, let me tell you about my experiences with that.
Most of the times I had explosions they were self inflicted. Starting the purge timer shortly after shutdown was the culpret. My Gun didn't short cycle much because it was a little large for the load. The smoke was hard to take but when I saw the flame that came with some I decided to go through the wall with it. It became a magnet for hornets and wasps that were looking for a new place to build a home so I got a nice little aluminum hood (the ones they use on single 100 lb propane tanks) Looked good. I didn't have to look at a hole in the wall. I then put 1/8 inch hardware cloth on the opening.The first explosion sent it about thirty feet out into the back yard with about 10 square inches of cedar siding attached. Decided that the mesh didn't allow the gas to escape quick enough so I removed it. Next explosion did the same thing. I concluded after a few more that the gasses don't like to turn corners.
Hmm. I appreciate the experience.
Did you bring your intake down to the floor first and then back up?
The only 2 times that I have gotten a puff were when the cycle timer kicked on just after the boiler shut down from a normal cycle.
If Coal Reaper's idea with the relay resolves that, I shouldn't have much to worry about with the explosions.
To avoid these "explosions" I have done nothing other than to avoid exactly what Fred states, which IMHO is operator error, and not purge soon after a shut down. I have not had one of these happen except in the very early days of operating the boiler. Actually, most of the initial shortcomings for me with this boiler were operator error of one form or another.
What is the advantage to bringing in outside air? I suspect none for me as my basement is certainly not a sealed environment?
Trust me, I (myself) am not causing the explosions. Only the cycle timer does. When I have run down stairs to the smoke detector going off, the cycle timer has always been engaged.
My basement isn't sealed either. I have 1980 steel windows and a set of hurricane doors. LOL
I have my intake air coming from outside. Installed it that way from the start...A plumber buddy of mine help/did the install and has done a few others and this is what he always does. My little house has a pretty tight basement so I think its a good idea anyway. I've heard a puff-back once when I was at home and came home another time to find the intake flap shut so I'm assuming it happened then too. Not that it's really been a problem for me but I like the idea of an automatic-reset timer. Maybe I'll poke around the Grainger catalog and see what's there.
"repeat cycle time delay relay" may be just what you need. if you have a grainger book then you might also have an msc, page 3566 in my old 2009/2010 msc book. however, this ones range only goes to 30 minutes. you would just need to find a what to cut power to the relay when the WG is doing its own thing.
I honestly don't remember. It didn't interfere with the door if I remember correctly so it couldn't have gone too far down.
That sales pitch was why I didn't buy a woodgun. At first I liked the apparent simplicity and the off the shelf controls. But telling me that I could stuff it full like an OWB, let it cycle on and off and be fine.... Just as long as you 'upgrade' to stainless. Didn't pass the straight face test for me. Sounded more like what I'd expect to hear from Larry B at the county fair.
So far, so good over here using that strategy.
I'll let you know when it fails.
Actually, ah, yes, that's exactly right. I'll admit there are some quirks with these things you need to work through but once you do they're as simple as it gets, plus no need for storage and no need for a dump zone. Put wood in it a couple times a day and forget about it. Even if that's not how your boiler works I would want a stainless firebox. Regardless of the brand or how they operate, its the corrosion inside the firebox that kills a boiler.
this here. but without knowing the schematics of the WG i would think you will need another NC relay to cut the power going to this timer when the WG is on due to call for heat. then when WG shuts down the NC relay will close and start the timer all over again.
One thing that came to mind on bringing in outside air which you should know in advance is thay the cold air entering really cools the box and flap causing the flap to collect condensation. It makes for a pretty gooy, smelly mess in the box. I remember spooning out the puddle on several occasions. The other problem as a result of the condensation was that it caused the silicone gasket on the flap to strech which caused it to ripple, eventually causing it to not close tightly and allow air into the firebox. Mine went into overheat a couple times. Blew the t/p valve and made some steam. First time it took a few minutes to locate the problem.
I could see how that would occur. They put a good slope on the tube from the flapper into the fire. Any creosote that happens in there seems to drip well into the firebox and burn. There is quite a lip from the box to the tube though, so anything that collected there wouldn't be going anywhere. Good warning!
I really think Coal Reaper's idea might be the ideal solution. In fact, I am curious as to why AHS didn't just do it that way. It's significantly cheaper than the timer.