Harman VF3000 Flue Temp

Stoker Coal Boilers automatically feed the coal and have controls and pumps just like any conventions boiler. They are intended to be used as a primary heat and often have domestic hot water coils as an added bonus. They can be set up independently or in dual sytem with your existing oil/gas boiler. They can accommodate both hot water base board or steam plumbing.
Jimeeh1970
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Stoker Coal Boiler: Harman VF3000
Other Heating: Napoleon 1401i wood insert
Stove/Furnace Make: Harman/Napoleon
Stove/Furnace Model: VF3000/1401i
Location: Pardeesville, Pa

Post Wed. Jan. 22, 2014 5:21 pm

Enjoying the lovely weather of NEPA today so I'm trying to squeeze more heat out of my Vf3000. Think I may be experiencing some coal quality issues. Anyway, does anyone know what the max recommended flue temp or the highest they've ever seen, for the Harman VF3000? Wanna go as high as I can without a meltdown.

Thanks,
Jim

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McGiever
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Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
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Location: Junction of PA-OH-WV

Post Wed. Jan. 22, 2014 7:29 pm

Thought it was all about a full burning grate and not pushing hot coals off the grate.

Watch adding excessive air... Could make fire box go Positive pressure and leak into house.
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BrotherDave
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Stoker Coal Boiler: Harman VF3000
Hand Fed Coal Stove: Godin 3727 / King KCC205
Stove/Furnace Make: King/Godin/Harman
Stove/Furnace Model: KCC205/3727/VF3000
Location: Stroudsburg, PA

Post Wed. Jan. 22, 2014 7:40 pm

When burning at full tilt my flue temps run between 100 and 125 degrees after the baro.
"Just when you think you know all the answers... I change the questions!!" - Hot Rod

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Rob R.
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Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Wed. Jan. 22, 2014 7:46 pm

BrotherDave wrote:When burning at full tilt my flue temps run between 100 and 125 degrees after the baro.
Not trying to nit-pick, but flue temperatures after a baro will change depending on how much air is flowing into the baro...so it is not a good point of reference.

You can feed as much coal as the stoker will burn and still maintain an ash ring at the edge of the grate. Watch for clinkers when you start pushing it hard.

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BrotherDave
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Stoker Coal Boiler: Harman VF3000
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Stove/Furnace Model: KCC205/3727/VF3000
Location: Stroudsburg, PA

Post Wed. Jan. 22, 2014 8:18 pm

Nitpicking is fine. The vf is running full tilt right now, the grate is full. I keep the feed rate so it maintains an inch of ash before the grate ends. The temp on the tee at the flue exit is reading 150. Hope this helps.
"Just when you think you know all the answers... I change the questions!!" - Hot Rod

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KLook
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Stoker Coal Boiler: Harman VF 3000
Coal Size/Type: rice, bagged, Blaschak
Other Heating: Gas boiler backup/main
Stove/Furnace Model: VF 3000
Location: Chattanooga, Tenn

Post Wed. Jan. 22, 2014 8:24 pm

Mine would run about *230 right after the collar at a "T". the baro was in the open end of the T and the other went up the chimney. I could not run it hard enough to say it could have a melt down.

Kevin

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oliver power
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Stoker Coal Boiler: KEYSTOKER Kaa-2
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Baseburners & Antiques: MANY (Mostly when burning wood)
Location: Near Dansville, NY

Post Wed. Jan. 22, 2014 8:25 pm

BrotherDave wrote:Nitpicking is fine. The vf is running full tilt right now, the grate is full. I keep the feed rate so it maintains an inch of ash before the grate ends. The temp on the tee at the flue exit is reading 150. Hope this helps.
I think you just about have it. My Kaa-2 is running full tilt right now. My flue temp in this cold snap are reading 150 before the baro.

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KLook
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Stoker Coal Boiler: Harman VF 3000
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Location: Chattanooga, Tenn

Post Wed. Jan. 22, 2014 8:28 pm

Keep in mind the boiler is only limited by the size of the stoker bed. I believe you could put a larger stoker in it and make more hot water. It would not melt an ASME rated vessel with 50 gal. of water in it.

Kevin

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2001Sierra
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Location: Wynantskill NY, 10 miles from Albany

Post Wed. Jan. 22, 2014 9:34 pm

Keystoker 90 running full tilt 180 degrees before baro.

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coaledsweat
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Post Wed. Jan. 22, 2014 9:41 pm

If you are worried about the stovepipe it will turn cherry red before it actually starts to melt. That said it will have to get north of 1000° to do that.
Nothing is impossible for people who don't have to do it themselves.

Jimeeh1970
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Stoker Coal Boiler: Harman VF3000
Other Heating: Napoleon 1401i wood insert
Stove/Furnace Make: Harman/Napoleon
Stove/Furnace Model: VF3000/1401i
Location: Pardeesville, Pa

Post Thu. Jan. 23, 2014 7:07 pm

Reason I'm asking is I don't want to damage the unit. As I stated, I think I have some coal quality issues and I'm trying to push the thing as hard as I can. I have a custom control system and I actually have flue gas feedback which is sampled at about a foot after it leaves the stoker and I'm using it as a safety, just not sure where safe/pushing it to hard limit is. I currently have it set for 345 and it has reached it a few times though I just did a fill up from a different side of the pile and it does seem to be burning more efficiently.

Jim

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coalkirk
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Stoker Coal Boiler: 1981 EFM DF520
Coal Size/Type: anthracite/rice coal
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Post Thu. Jan. 23, 2014 8:39 pm

Jim, sounds like you are talking actual flue gas temps which is how I would measure it also. I think everyone else has been talking stove pipe surface temps. I measured mine after the baro and it was in the 260* range. I think before the baro is was about 345*.
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Burning rice coal in a 1981 EFM DF520, nut coal in a hand fired Jotul 507.

Jimeeh1970
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Stoker Coal Boiler: Harman VF3000
Other Heating: Napoleon 1401i wood insert
Stove/Furnace Make: Harman/Napoleon
Stove/Furnace Model: VF3000/1401i
Location: Pardeesville, Pa

Post Fri. Jan. 24, 2014 5:57 pm

Yes...I am measuring flue gas temp with an RTD inserted in the stack. Sorry for the confusion. Just wish I knew what the highest "safe" temp would be.

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KLook
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Stoker Coal Boiler: Harman VF 3000
Coal Size/Type: rice, bagged, Blaschak
Other Heating: Gas boiler backup/main
Stove/Furnace Model: VF 3000
Location: Chattanooga, Tenn

Post Fri. Jan. 24, 2014 7:58 pm

I think I asserted before that you could not run it hard enough to ruin anything. Your flue temp is childs play compared to a wood fire in the same kind of pipe. How is it going to hurt the boiler vessel when it is filled with 50 gal. of water?

Kevin

Jimeeh1970
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Posts: 28
Joined: Thu. Aug. 12, 2010 9:00 pm
Stoker Coal Boiler: Harman VF3000
Other Heating: Napoleon 1401i wood insert
Stove/Furnace Make: Harman/Napoleon
Stove/Furnace Model: VF3000/1401i
Location: Pardeesville, Pa

Post Fri. Jan. 24, 2014 8:44 pm

Don't disagree with you kevin. Just looking for info. You as a VF3000 owner understands harmans highly technical owners manual publication which states don't go over three dots on the pusher stroke or damage to unit may occur. I'm currently a little over 2 and have seen variances where the the red hot coals are flowing over and the stoker is struggling to keep up vs today where I have 3/4" of burnt out ash but my stoker is over temping at 350* flue gas temp. I would really like to put the set point at 500* and let it fly but I'm just proceeding with caution.

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