Can't Fire EFM 700 Over 4 Teeth.

 
bobok
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Post by bobok » Wed. Nov. 19, 2014 6:20 pm

My friend has an EFM 700 boiler and stoker. :) He can't seem to get enough fire when the radiant heat in the shop floor dumps back to the boiler :( . He has good draft (.4), and burning buckwheat from hazleton shaft, nice looking coal. Setting is 4 teeth and 3-1/4 air. Any Ideas :?: :?: :?: Thanks, Bobok


 
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Rob R.
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Post by Rob R. » Wed. Nov. 19, 2014 6:27 pm

Bob, the title of your post makes it seem like they can't get the stoker to run over 4 teeth. Does it not run properly when they set it at 5 or 6 teeth?
bobok wrote:He can't seem to get enough fire when the radiant heat in the shop floor dumps back to the boiler :(
Radiant slabs can soak up a lot of btu's, special piping techniques are used to make sure it doesn't overwhelm the boiler. Perhaps he just needs to increase the feed & air, but it would be nice to see some pictures of the radiant piping and the boiler piping.

 
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Post by franpipeman » Wed. Nov. 19, 2014 6:56 pm

Having a properly sized piping and bypass and also maximize the differential of your aquastat , which allow the heat to be stored in your boiler, and helps to avoid pump shut down due to cool water temps helped me run my 85K in joist staple up system ,

 
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Post by bobok » Wed. Nov. 19, 2014 7:03 pm

He replaced a hand fed burning stove coal and used to return to a 500 gal storage. This absorbed the dump fron the floor. but as you know the slab holds heat forever but then sends cool water back when it finally does call. He hoped to eliminate the storage by going stoker and 700. It does well but when the slab calls and it has to run for 45 min to 1 hr, to catch up the fire dies off toward the end of the time frame. It should, I would think, keep a consistent burn . The shop is new and well insulated, there are tempering valves as needed. I was wondering if he shouldn't just turn the tempering valve to cool and let the shop circulate all the time. I too have two shops with radiant slabs and am considering doing just that. I will be going to a 700 in a month or so. Bobo

 
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windyhill4.2
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Post by windyhill4.2 » Wed. Nov. 19, 2014 7:20 pm

:? I'm still confused,why can't he fire it over 4 teeth ?? With higher feed rate there needs to be a higher air rate too. You are saying he can't set it for 5 teeth & 5 air ? I am also confused on the idea of the floor system "dumping" on the boiler,why on earth would that not be set up with a constant circulation Which would eliminate the temp roller coaster .

 
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Post by bobok » Wed. Nov. 19, 2014 7:44 pm

Have been told by a reliable source that the 700's blower is more than it needs and probably never go over 6. 5a & 5c will simply blow the fire out which is exactly what was happening at 3 and 3. However, getting over 4 teeth and 3.25 air works for 10 to 15 minute intervals, but not when the slab calls. Bobo. By the way thanks to all responding.

 
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Post by Pacowy » Wed. Nov. 19, 2014 8:00 pm

I have run a 700 stoker and I don't know what is meant by the fire being blown out. With a proper fuel/air mix and coal of reasonable quality and sizing, that unit should be really ripping after a run of 45 minutes-1 hour. Does the pot become covered with unburned coal? Ash?

Mike


 
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windyhill4.2
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Post by windyhill4.2 » Wed. Nov. 19, 2014 8:24 pm

How BIG is this shop ? I just reread your posts,with the limited operating knowledge I have with the EFM520 combined with common sense schooling learned from growing up on a farm I would venture to say that what you describe as fire out in 45-60 min, is just tooo much fuel for the fire. If you add to much air the fire will crawl down into the pot,feed too much fuel for too little air & the fire gets smothered.It might be more complicated than that but I like to start with the simple possibilities & work towards the difficult.

 
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Post by Pacowy » Wed. Nov. 19, 2014 8:30 pm

windyhill4.2 wrote:How BIG is this shop ? I just reread your posts,with the limited operating knowledge I have with the EFM520 combined with common sense schooling learned from growing up on a farm I would venture to say that what you describe as fire out in 45-60 min, is just tooo much fuel for the fire. If you add to much air the fire will crawl down into the pot,feed too much fuel for too little air & the fire gets smothered.It might be more complicated than that but I like to start with the simple possibilities & work towards the difficult.
x2. The important thing is to maintain the fuel and air settings in relation to each other so that the unit produces an ash ring about 2" wide after it has run for 30-45+ minutes. If the ash ring keeps getting bigger or smaller then feed or air adjustments are needed.

Mike

 
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Post by bobok » Wed. Nov. 19, 2014 10:58 pm

Thanks Mike, I also think it is a setting problem but his 700 seems pretty sensitive to changes in the settings. It definitley needs a higher coal than air setting. When we figure his out I will have an easier time when I get my boiler back from being retubed. I wonder if anyone else is running a 700 at a high firing rate :?: :?: :?: Bobo.

 
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Post by Pacowy » Wed. Nov. 19, 2014 11:29 pm

You're welcome Bobo. When making those adjustments it's best to make small ones and give them time to take effect. Sometimes the unit may appear to be sensitive, but what's really happening is the operator makes a change, observes no immediate effect, and then makes an additional change that (cumulatively) appears to have a big effect.

Mike

 
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Post by bobok » Thu. Nov. 27, 2014 9:53 am

Well, we tried an experiment and used rice instead of buck and the difference was night and day. Before it took 2 minutes to raise 1 degree. With the rice on 4 teeth, 4 air it raised 10 degrees in 4 minutes :!: It seems as though our buckwheat although very consistent in size, has very little fines. The blower pushes air through the coal too fast and puts the fire out. With the rice, the flame goes up, curls over and down, then curls back up and out! two to three times more flame :!: :!: . The coal came from Hazelton shaft and is great looking, clean and as I said consistent, but too porous. It was interesting to notice that the old factory instructions some one had posted on an efm had a hand written note saying "don't use buckwheat" Any thoughts :?: :?: Bobo

 
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Post by windyhill4.2 » Thu. Nov. 27, 2014 10:02 am

I originally had planned on using buck in my 520,but after reading some heated debates on the subject here on the forum & getting some pm's from some members who had burned buck but since have switched to rice & are enjoying less grinding sounds with less outfires,i bought rice & am very pleased with how everything is working so smoothly. Thanks for the update,i was wandering what was happening,glad to hear that it is working out for you.

 
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Post by bobok » Thu. Nov. 27, 2014 10:31 am

Thanks Windyhill! Like I say it was an experiment . Next we'll see if we can mix rice with the buck as he bought the buck in bulk. Will keep you posted. Bill (Bobo)

 
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Post by bobok » Thu. Nov. 27, 2014 10:33 am

Oh one other thing, we have turned the temp valve down to cool and circulating on and off every 15 min to eliminate the slab dump . Bill


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