Boiler Firing Via Room T-Stat's , or Via Internal Aquastat?

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.
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lsayre
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Posts: 12185
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Sun. Oct. 27, 2013 8:56 pm

AHS Coal Guns fire (initiate their fan motor) only when their own aquastat monitored internal temperature falls to or below a pre-selected level. Other boilers seem to fire primarily based on a room (zone) T-Stat's call for heat (with a high limit aquastat delaying/preventing this firing as necessary to avoid dangerous boiler overheating situations from ever occurring), and secondarily from the boilers internal temp falling to a pre-selected level. What potential advantages or disadvantages are there for either of these firing methods? Is one method potentially more efficient than another?

One disadvantage I can see for the Coal Gun method is that with coal recovering slowly from its slumber between firings, it seems advantageous to have the T-Stat initiate firing so by the time the boilers temp starts to drop internally it is already firing and starting to catch up, whereas for the Coal Gun this does not occur.

One advantage I can see for the Coal Gun is that occasionally a T-Stat heat call is satisfied without the boiler needing to fire at all, or with the boiler hardly needing to fire at all, and this could potentially save coal.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

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Rob R.
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Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Sun. Oct. 27, 2013 9:24 pm

Generally speaking, if the boiler spends a lot of time with no load, maintaining a lower temperature will reduce standby losses. If the boiler is in an outbuilding with underground piping, the difference can be substaintial.

Using a tankless coil limits your flexibility with the operating temperature. Even if you had a different control the boiler would still need to maintain 160F or so.

franco b
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Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea
Location: Kent CT

Post Sun. Oct. 27, 2013 11:17 pm

The traditional and conservative way is to have the thermostat control the circulator only. The aquastat starts the burner. Starting the burner as well as the circulator is an advantage with slow recovering systems.

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lsayre
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Posts: 12185
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Mon. Oct. 28, 2013 5:46 am

franco b wrote:The traditional and conservative way is to have the thermostat control the circulator only. The aquastat starts the burner. Starting the burner as well as the circulator is an advantage with slow recovering systems.
Thanks! Perhaps the Coal Gun is wired more traditionally than I thought.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

Visit Alternate Heating Sytems

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Rob R.
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Posts: 11342
Joined: Fri. Dec. 28, 2007 4:26 pm
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Mon. Oct. 28, 2013 6:05 am

Some sort of "reset" control to adjust the temperature of the boiler based on outside temp. and/or demand would save some coal. I have done this on my own system...right now it is keeping my house very comfortable with 150F water. I installed a reset control on my dad's EFM also...he said his basement averages 3 degrees cooler due to the cooler boiler operating temperature. I have been using the Hydrostat controls, but there are other options.

Study on outdoor reset savings: http://www.heatinghelp.com/files/posts/9700/outdo ... _reset.pdf

Honeywell reset controls: http://www.forwardthinking.honeywell.com/related_ ... 9_1974.pdf These controls are probably the most complex I have seen, you can adjust boiler temp. based on outdoor or indoor thermostat feedback, set it to purge heat from the boiler after a heat call, etc. Another forum member had one of these on an AA260, he said it totally eliminated an overheating problem after long burns. There is something to be said for keeping it simple, but at least you know what else is out there.

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lsayre
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Posts: 12185
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Mon. Oct. 28, 2013 6:14 am

Another way to greatly boost overall system efficiency is to bring in outside combustion air. With each pound of coal burned needing 123 cubic feet of air, that becomes a lot of air infiltration that brings cold air that must be heated right into the rooms of the home. My electric resistance boiler did not draw in any air as it didn't need it. So even if my boiler truly is 80 percent efficient, my overall system efficiency is only about 65%, with at least some of that being due to having to heat so much outside air that the boiler is dragging in from sources throughout the home.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

waldo lemieux
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Stove/Furnace Make: efm
Stove/Furnace Model: s-20
Location: Ithaca,NY

Post Mon. Oct. 28, 2013 8:06 am

What somebody needs to get working on is a control that "learns" how your system works to heat your house based on changing conditions outside,ie temp change , wind speed /direction , atmospheric pressure , maybe even % cloud cover and adjusts your system settings based on historical data. It may sound complicated but I gotta believe with today's technology its within easy reach. Maybe the gains in efficiency (savings) to be had arent yet great enough ,but thats only at current energy costs. Somebody here needs to get crackin' :ugeek:
When faced with a seemingly impossible task, my grandfather always said "can't never can, untill try comes along"

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Sting
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Other Heating: OBSO Lennox Pulse "Air Scorcher" burning NG
Location: Lower Fox Valley = Wisconsin

Post Mon. Oct. 28, 2013 9:08 am

outdoor reset controls == somebody needs to to invent this -- Seriously???

I installed my first electronic reset control in the early 70's - very simple device compared to the junk now in production
bulb / mechanical versions were in use before I was a twinkle in my daddies eye!
HUMANS/ Dirty men covered in wood - oil and or coal dust- employed as boiler tenders ----slaved at this since water circulated heat energy in buildings - they were the first out door reset controls

an autonomously temperature controlled boiler is a happy boiler
When you turn your boiler on -Does it return the favor?
I have finally lost my mind. Don't bother to return it. It wasn't working properly anyway!

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waldo lemieux
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Posts: 2261
Joined: Sun. Sep. 30, 2012 8:20 pm
Stove/Furnace Make: efm
Stove/Furnace Model: s-20
Location: Ithaca,NY

Post Mon. Oct. 28, 2013 9:22 am

So this animal already exists. It "learns your system" and makes adjustments based on the history of its experience? What is the name of this unit, speak it ...please! I know there are things (tekmar controls) that will adjust your boiler but I thought it did so based on settings you the operator provide and not based on its own observations of system efficiency. Damn I gotta get out more :oops: Please advise as to a website and any personal experience. Maybe this should be its own thread, Rob this may be a place for some moderator wizardry ... standing by...
When faced with a seemingly impossible task, my grandfather always said "can't never can, untill try comes along"

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lsayre
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Posts: 12185
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Mon. Oct. 28, 2013 10:12 am

I just ran some numbers indicating that my system efficiency could increase by roughly 4% to 5% overall if I brought in combustion air from the outside instead of having my boiler suck in air from the various leaks, nooks, and crannies all over the home.

If each pound of coal requires 123 cubic feet of air supply to properly burn, and that same 123 cubic feet of air weights about 9.5 lbs (give or take), and that 9.5 lbs are coming in through the homes various leaks at say 20 degrees and in need of being heated to 70 degrees, then each pound of burned coal is causing the homes BTU demand to rise by 50 x 9.5 = 475 BTU's. If you burn 45 lbs of coal per day, then on average that represents 21,375 BTU's that you are wasting every day of the heating season just to heat the cold air that the boiler (stove, furnace) is dragging in, or nearly 2.5 lbs of coal. 2.5 lbs. of wasted coal for each of the roughly 200 heating season days per year is 500 lbs. of coal wasted annually heating air infiltration unnecessarily. Not to mention that the comfort level of the house is reduced by the cold air being dragged in.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

franco b
Site Moderator
Posts: 8416
Joined: Wed. Nov. 05, 2008 5:11 pm
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea
Location: Kent CT

Post Mon. Oct. 28, 2013 11:12 am

There is also a safety factor since the air supply is no longer effected by other influences in the house such as dryers and exhaust fans.

User avatar
Sting
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Posts: 2970
Joined: Mon. Feb. 25, 2008 4:24 pm
Other Heating: OBSO Lennox Pulse "Air Scorcher" burning NG
Location: Lower Fox Valley = Wisconsin

Post Mon. Oct. 28, 2013 11:16 am

Yes - outdoor air will make the appliance run better - just as a clean air filter will make your car run better

and - since your not aggressively pulling drafts thru your living room window - you will be more comfortable sitting in you evening "jammies"
When you turn your boiler on -Does it return the favor?
I have finally lost my mind. Don't bother to return it. It wasn't working properly anyway!

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