FAQ for the Flame King Furnaces & Boilers



 In the fall of 2005, when I began to investigate starting a business dealing with coal furnaces and boilers in Fairbanks, I had a lot of questions.  Many of them I felt might be of interest to my customers, so I've developed this FAQ.  I hope you find these Frequently Asked Questions useful!   They are mostly based on the answers I got to my questions to people who run coal furnaces, the factory, etc.  If you have any other questions I'd be happy to answer them to the best of my ability. 


Ray R. Collins

Q: How does a coal boiler work?

A: The way the boiler works is to auger the coal from the bin or hopper up onto a flat plate with air slots cut into it.  There is a blower that blows air through the slots and the coal burns very hot.  When there is no call for heat (ie the water in the boiler is hot) the auger and blower shut off.  The fire will continue to burn, just very slowly.  When there is a call for heat (ie the water in the boiler has cooled off) the auger and blower turn on, delivering more coal to the fire.  This arrangement works real well and is completely automatic (though it does need to be checked regularly).


Q.  How messy is coal heat?

A.  If you build an out-building to keep the dust away from your dwelling there isn't any.


Q.  Does it smell?

A.  Coal smoke has a distinctive smell.  Some people don't like it, but if correctly situated away from your dwelling it shouldn't be a problem.  If you don't keep it functioning correctly and wind up with burn-back (where the fire works its way down the auger toward the coal bin) it does get very smelly, but this is a pretty rare occurrence from what I've been told.


Q.  How do you dispose of the ash?

A.  Many people spread it on their driveway during the winter to provide traction.  Other possibilities are to take it to the dump; it makes an excellent base (partly in place of sand) for concrete, anywhere you need fill dirt, etc.


Q.  How much ash does it produce?

A.  7-10% of the coal volume is ash.  So if you use 10 cubic yards (this is about 6 tons) of coal you'll wind up with about a cubic yard of ash.


Q. How heavy is the ash?

A.  It is pretty light in my experience.  


Q: What types of things do I need to check the Flame King boiler for and how often?

A: Coal fires need a lot of attention.  They develop clinkers on the burner head which need to be cleared for efficient burning (preferably daily).  The tubes tend to ash up and so need to be swept (preferably once a month, more often during heavy use)--if they aren't the efficiency drops off pretty fast.  Bits of rock and other debris in the coal can jam the auger and if this happens it will sheer a pin in the auger that will need to be replaced, and if reversing the motor fails to clear the jam, you may have to shovel all the coal out of the coal bin (or if your bin is equipped, shut off the coal feed) to get at whatever is jamming it.  The chimney should be brushed out every year, the motors should be oiled every year (and checked more often).  Belts should be changed every 4 years. 


Q: Should I keep my oil furnace/boiler as backup?

A: Though not required, it would be a good idea. With the potential problems with coal (especially a jammed auger), it isn't safe to leave a house heated with coal any longer than it would take it to freeze, which ties you down pretty bad during the winter unless you keep your oil unit for backup—or if someone can keep an eye on it ever day or so.  Coal & Heat Inc will be offering a full service and maintenance agreement for Fairbanks starting in the fall of 2007, which will avoid these problems (with automatic notification of boiler problems/failure). 


Q: What is the equivalent between coal and heating oil?

A: 1 ton of coal is very roughly equal to 100 gallons of heating oil.  So if you were to use the 400 pound hopper, it would run about as long as an oil fired unit would on 20 gallons of heating oil.  To be more exact, a ton of Usibeli coal usually has 15,000,000 BTU (100 gallons of oil has about 12,000,000 BTU).  With 80% efficiency in oil and 70% efficiency in coal, 100 gallons of oil equals 0.91 tons of coal.  Of course the cost of coal per ton is far, far less than oil.


Q: What type of foundation should I set my Flame King boiler on?

A: These furnaces are very heavy; 1,400 pounds for the Model 125 and 1,600 pounds for the Model 220.  I recommend a concrete pad to set it on, and if not then whatever it is on needs to be fireproof. 


Q:  What do I hold the coal in?

A:  You can use either a coal bin or a hopper to hold the coal.  The coal bin will be more expensive to set up, but you can build it large enough so you'll only need 2-4 deliveries a year and you won't need to shovel coal (usually the dump truck can just dump it right in).  The hopper would probably be cheaper and easier to clear if it jams.  Some people go with both systems, using an auger/conveyor to transfer coal between the bin and the hopper.  


Q: If I use a coal bin, where does the bottom of the bin need to be in relation to the furnace?

A: The bottom of the coal bin needs to be only slightly higher than the bottom of the furnace. I would suggest building either on a hillside so the coal can be loaded above the boiler or have the boiler room below grade.


Q: Can I just put the new Flame King coal boiler where my furnace is now?

A: While it probably is possible to install the Flame King where your furnace is now, it is a better idea to build a small outbuilding away from your main building. This way, in the unlikely event of a fire in either the furnace or coal, damage would be limited to the outbuilding and won't burn down your main building. For this reason, insurance rates are lower if the new Flame King boiler is in an outbuilding. Plus, any dust would be contained in a separate building. However, the outbuilding can get expensive. 


Q: What are the fire hazards associated with coal boilers?

A: If there is no call for heat for prolonged periods, or if the auger jams, there is the possibility the fire will burn down the auger tube into the coal hopper/bin.  This is, of course, a considerable fire hazard; though I haven't found anyone who has had a serious fire as a result (even should the fire reach the hopper it still won't burn very fast because it won't get enough oxygen). Still, I strongly recommend against having the outbuilding near any other structures if at all possible.


Q: How much copper pipe do I need and what will it cost?

A: Copper pipe is expensive, especially in larger sizes (1.5" is about $5/foot as of January 2006). You will need twice the distance between the boiler and where it will tie into the existing heat system.  One for the supply line and one for the return.  The diameter you will need depends on the heat load.


Q: Should I use anti-freeze (glycol) in the pipes?

A: Yes. Anti-freeze protected system should be used in case the coal boiler is down long enough for the plumbing to freeze between it and your main building(s).  With older installations this may cause problems with the existing plumbing (antifreeze may cause it to leak), so an alternative is to put heat tape on the plumbing.


Q: I burn about 1000 gallons of heating oil a year. Is it cost effective to switch to coal?

A: I am not sure that burning 1,000 gallons of heating oil a year would justify the cost of installing a coal boiler.  Even if you do all the work yourself it is still a very expensive proposition.  Here in Fairbanks it is cost effective to install a coal furnace/boiler for people who burn more than 3,000 gallons of oil a year assuming a price of $2.25/gallon for heating oil.  The advantage to doing it now is that if the cost of heating oil goes up much more I would expect a very long waiting time between ordering and delivery.


Q: When should I order a Flame King coal boiler?

A: There is a considerable lead time to build a boiler. As each boiler is individually made, it takes the factory about a month to put one together. Delivery then takes 2-3 weeks.  The factory can get very backed up and you should plan at least 3 months in advance, occasionally a lot longer.  Eventually I hope to stock a few in Fairbanks, though that may not be for a couple of years.



Ray's Installation Questions

Q. What is considered non-combusitble?

A.  5/8 sheetrock over wood studs is acceptable.  Some installations use all metal construction; others use metal over studs, with the metal spaced out 1.5" to provide the fire barrier.


Q.  How much air does the burner need?

A.  114-148 cubic feet per minute (CFM).


Q.  How much does the boiler weigh?

A.  Ship weight for the Model 220 boiler is 1,600 pounds.  The base is about 200, and other parts around 100-300 pounds (depending on setup).  The boiler weighs about 1,100 pounds [need to verify this].


Q.  What angles are needed inside the coal bin?

A.  45º angles will usually allow all the coal to slide down to the auger.


Q.  Will it hurt furnace cement to freeze?

A.  Probably.


Q.  What factors determine whether the hold-fire timer needs to be adjusted up or down?

A.  If it goes out, increase it.  If the boiler gets too hot, decrease it.  You have it right when the fire stays lit without running the boiler temperature up.  Note: the hold-fire timer turns on the auger briefly every half hour, to keep the fire going and prevent the fire from burning back down the auger tube.


Q.  How long is to long to leave it unattended?

A.  2-3 days, depending on heating demand (more frequently if more heat is used; longer times if less heat is needed).


Q.  It is recommended to add a little oil to the coal (1 gallon/ton); what happens if you don't?

A.  Oil helps the coal burn and also provides lubrication as it goes through the auger.  If you don't oil it you boiler may not work quite as designed, though many people do not oil the Healy coal, which is very soft, without incurring problems.  If you do want to oil your coal you can just dump oil over it, or add an injector over the auger tube.  1-2 gallons/ton is best.


Q.  How do you service the burner head, and how often should it be done?

A.  You clean the tuyers (slots) with a hacksaw blade.  When the boiler is used lightly you can clean it annually, if heavily used you may have to shut it down mid-winter for an extra cleaning or two to maintain peak efficiency.

Q.  How often do you lubricate all motors & oil points?

A.  Annually.  Use non-detergent 20-30 weight oil.


Q.  Is there a pin made that will send an electric signal when it sheers?

A.  Yes, but it is not currently available.


Q.  How do you reverse the direction of the stoker motor?

A.  Switch the red and black wires on the motor.


Q.  What are Tuyeres?

A.  Slots the air comes through in the burner head.


Q.  How often does burn-back occur?

A.  Very seldom.


Q.  Most of the coal bins I've seen have a lot of wood in them--ie they'd burn.  Is this a problem?

A.  No.  The factory does not know of any coal bins that have burnt down from burn-back.  The possibility exists though, so the coal bin should be located away from other structures.


Q.  Would thermal shock be a problem with a Flame King boiler?

A.  Very unlikely (it is not nearly as susceptible as cast iron), but a mixing valve would be a good idea where long runs of pipe could get very cold.


Q.  When you have a wide range of firing conditions (eg -60º F to 50º F) should you re-adjust the air supply?

A.  It is unlikely you would need to do this.


Q.  With the hold-fire is there ever any problem with too much heat?

A.  No; if water gets too hot the aqua stat turns it off.


Q.  Do you need to condition combustion air?

A.  It should not be too cold; ie do not pipe it straight in from outside.


Q.  What is the normal chimney temperature?

A.  Model 220: 300-350º F.  If it is over 350º then you are over-firing the boiler.


Q.  Are ash augers included in the boiler price?

A.  No.


Q.  Is there a (summer) minimum heat demand needed by domestic hot water?

A.  No minimum, the hold-fire will usually keep the fire going all summer if that is desired.  Of course if it is running all summer you'll need to maintain it all summer too.


Q.  Can I get my domestic hot water from the boiler?

A.  Yes


Q.  What is the warranty and can I get an extended warranty?

A.  1 year.  Currently we do not have an extended warranty available, but we hope to have one by the end of 2006 that will extend out as long as 5 years from purchase date.


Q.  How long do coal augers last?

A.  4-20 years, depending on firing rate and coal quality.


Q.  How long do ash augers last?

A.  They almost never wear out.


Q.  How many of these furnaces have been built?

A.  When King Coal was building them (starting in the 1980's), they built over 3,000.  There was a bit of a hiatus, but A-Z Manufacturing has geared up to full production starting with their first boiler in 2001.


Q. Is there CO output?

A.  As with all fires burning fossil fuels, there is a chance of CO, and it should be guarded against by assuring proper installation of the chimney.  If installed within a living area we strongly recommend a CO alarm.


Q.  How high does the chimney need to be?

A.  This varies with installation; it needs to be well above the ridge-line (see instruction manual) to assure it will draft correctly during inversion conditions.


Q.  What size electrical breaker should I use?

A.  15 amp fuse should be used.


Q.  What spares do you recommend?

A.  Coal & Heat in Fairbanks intends to stock a full line of parts.  If you are not local in Fairbanks (or wish to be more self-sufficient) we recommend:


Q.  Are there EPA regulations I need to follow?

A.  No, not in Alaska until you get up to a million BTU/hour.


Q.  Is the Flame King UL rated?

A.  It is built to ASTM standards, but is not UL rated.


Q.  Is there a web site with more information?

A.  The factory has a web site at: http://flameking.net/


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