High Limit Causing Outfire

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.
daluds
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Stoker Coal Boiler: EFM DF520
Coal Size/Type: Rice
Stove/Furnace Make: EMF
Stove/Furnace Model: DF-520

Post Mon. Apr. 12, 2010 11:55 pm

Hello,

Is there a way to bypass the hi-limit shut off to keep the timer running? I have improved the draft with the setup I have for the DF-520, but still getting out fires since the stoker keeps hitting the high limit. It takes a long time for the temp to reduce below the hi limit, and the fire goes out. I reduced the on-time to 2 minutes per 30 minutes, and removed some insulation to try to get it to dissipate more heat. However, it keeps going out during warmer days without much call for heat. I have the hi limit set to 210 now, but also tried 200. Its been staying lit more with the hi limit set to 210, but rarely can keep it running more than a day or so in the warmer weather.

Thanks,

Dave

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stoker-man
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Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove
Location: Lehigh Valley, PA

Post Tue. Apr. 13, 2010 6:03 am

What is your draft at the flue pipe with the burner off and with the burner on and the flue fully heated up?

Set your low limit down to 140 and your air and feed to 4/4
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daluds
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Posts: 282
Joined: Fri. Jun. 20, 2008 9:27 am
Stoker Coal Boiler: EFM DF520
Coal Size/Type: Rice
Stove/Furnace Make: EMF
Stove/Furnace Model: DF-520

Post Sun. Apr. 18, 2010 12:35 am

Stoker-man,

I am getting -0.03 to -0.04 now. I have low at 150 to 160, and high at 210. Is there a way to bypass shutting off the timer when it hits the high limit or is there a way to wire up another aquastat for the timer only so it can run to a higher limit? I am also considering running an attic fan into the boiler room from outside to assist with the draft. The boiler room is separated from the rest of the house now with air from the outside.

Thanks,

Dave

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stoker-man
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Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
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Other Heating: Hearthstone wood stove
Location: Lehigh Valley, PA

Post Sun. Apr. 18, 2010 6:24 am

You can't allow the timer to work when you are over high limit.

See pages nine thru eleven in the manual. Check that all the holes in the grates are open. Clean with an ice pick through each hole. Lower your low limit to 130 and timer to 1 1/2 minutes per half hour.

Do you have both returns piped in and the bypass line?
DF 520 installation manual.doc
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daluds
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Posts: 282
Joined: Fri. Jun. 20, 2008 9:27 am
Stoker Coal Boiler: EFM DF520
Coal Size/Type: Rice
Stove/Furnace Make: EMF
Stove/Furnace Model: DF-520

Post Sun. Apr. 18, 2010 8:40 pm

Stoker-man,

I reduced the timer to 1 1/2 minutes every half hour. Will see how this works. The pot holes are open, and the coal burns great. This years coal burns much better than last years. I cleaned out the stove pipe and horizontal flue over the weekend. We get hot water from the boiler so don't want to set the low setting too low since the domestic water doesn't get hot enough. I might get a boilermate for hot water so can lower the low setting. Both returns are piped in, and I have the bypass open. Taking some of the insulation off helped lower the boiler temp too.

Thanks,

Dave

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stoker-man
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Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove
Location: Lehigh Valley, PA

Post Mon. Apr. 19, 2010 6:26 am

OK, make the low limit 140. That's what I always used for hot water. I have an indirect heater and that's also at 140º. It's just a zone. Your boiler has to be set at whatever your indirect is set at, meaning that you won't be able to have a higher temp for the Boilermate.
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AA130FIREMAN
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Stove/Furnace Model: 130 anthratube

Post Mon. Apr. 19, 2010 9:37 am

Add an aquastat that makes on rise(honeywell l4006b1155) for a heat dump zone, set a couple degrees lower than the high limit. Set it to run a circulator, not the boiler or it will want to run all the time.

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Coal Guzzler
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Stove/Furnace Make: Saey Stove/EFM Boiler
Stove/Furnace Model: Hannover Stove/DF 520
Location: Glenmoore, PA

Post Mon. Apr. 19, 2010 8:00 pm

Try removing some insulation from some connected piping. It will provide a heat sink for the boiler. It's an efficiency loss but will help keep the temperature of the boiler below the hi limit and help prevent outfires.

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markc
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Post Mon. Apr. 19, 2010 8:55 pm

i burn bit stoker and I lowered my on temp from 172 to 150 my timer is set at 30 min 30 sec iam not having any problem in 80 degree weather stove just sits and idles for days at about 5 gals of coal per day .different type stove than you have but timer and cut on temp I believe is the key
markc
once you burnt black you never go back
burning ky bit 13,900 btu

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stoker-man
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Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove
Location: Lehigh Valley, PA

Post Mon. Apr. 19, 2010 9:02 pm

For Mark, when I did the soft coal experiments, I found out you don't even need a timer with some of the bit. Went 3 days after I thought the fire was out.
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Pa Dealer
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Stoker Coal Boiler: EFM 520 DF
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Post Thu. Apr. 22, 2010 5:23 pm

Put tin foil around the draftastat to block it off to increase draft.

ry

daluds
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Posts: 282
Joined: Fri. Jun. 20, 2008 9:27 am
Stoker Coal Boiler: EFM DF520
Coal Size/Type: Rice
Stove/Furnace Make: EMF
Stove/Furnace Model: DF-520

Post Sat. Apr. 24, 2010 11:47 am

AA130Fireman,

I was considering buying a boilermate for hot water. Would this be a good dump zone? My wife is complaining about not having enough hot water to filler her big tub when running on oil, and of course complains more when the coal fire goes out! :-) I want to keep my EFM so need to figure this out in a hurry. I am going to look into buying a boilermate.

Thanks Stokerman for the information on the low setting with the boilermate. I think 140 or 150 will work if this temp is maintained in the boilermate, but with coal running the water temp with the tankless drops until the fire is hot again. Its a big tub of water she fills. In the winter this works fine since the temp hovers around 180-200.

Dave

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stoker-man
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Joined: Mon. Nov. 19, 2007 9:33 pm
Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove
Location: Lehigh Valley, PA

Post Sat. Apr. 24, 2010 12:17 pm

A boilermate or an Ergomax, efm's product, won't help you as a dump zone unless you keep it cold. The heating dump zone is a good idea because it will actually radiate/dissipate excess heat, where the indirect heater will not, unless you run the hot water.

An indirect heater, like the Ergomax E-23 will give you an endless supply of hot water for a home application. I have one myself and the way I use it in the Summer is to bring my wood boiler up to 140º, which also makes the indirect 140º. This requires a 5 gallon bucket of wood and I do it when I get home in the afternoon. Because the heat loss is only 1/2º per hour, I save what's in it for my domestic water the following day. I did a test one day and measured how many gallons of 50º well water it would take to go from 140 at the tap down to an uncomfortable 100º and it was 25 gallons of constant flow and that was 24 hours after I heated the indirect.

So, go for an indirect.
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AA130FIREMAN
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Post Sat. Apr. 24, 2010 2:21 pm

daluds wrote:AA130Fireman,

I was considering buying a boilermate for hot water. Would this be a good dump zone? My wife is complaining about not having enough hot water to filler her big tub when running on oil, and of course complains more when the coal fire goes out! :-) I want to keep my EFM so need to figure this out in a hurry. I am going to look into buying a boilermate.

Thanks Stokerman for the information on the low setting with the boilermate. I think 140 or 150 will work if this temp is maintained in the boilermate, but with coal running the water temp with the tankless drops until the fire is hot again. Its a big tub of water she fills. In the winter this works fine since the temp hovers around 180-200.

Dave
I would NOT use the boilermate as a dump zone (their is no where for the heat to disapate if their is no use), I have a vaughn indirect water heater and only heat to 140 and a mixing valve to drop it to 120. Are you only useing 1 zone for heat ? I have my air handler fan coil and a modine heater as my dump zone. This does not seem to overheat the house by more than a degree or 2. I like having the 2 as a dump zone incase the motor in the air handler /modine would fail, the motor burned up 2 years ago. I have the aquastat (honeywell l4006b1155) wired to the tt on a zone relay and that runs both circulators. I have a second aquastat that I will install soon , I am going to wire one for the air handler and the second to the modine then I can decide witch one will come on first and if something fails their is a back-up. Try useing the main zone as a heat dump unless it drives you out of the house. :D

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AA130FIREMAN
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Post Sat. Apr. 24, 2010 2:35 pm

The honeywell l4006b1155 has an adjustable differential from 5-25 , I'm set at 200 and the diff. at 5 so the fan only takes me 1 to 2 minutes to bring down the temp. and my boiler does not fire untill it's below 180. My timer bypasses the triple aquastat set at 180, but does NOT bypass the high limit set at 200, and the dump zone is at 200 to take down the temp below the high limit 200 so the timer can run.

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