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hydronic temperatures and pressures

leonz
leonz Member Posts: 682
I need to settle a debate;

I have a single circulator paired with the 15 gallon steel compression tank and a total of 54 gallons of water in a single loop system on one floor for heating this old shotgun school house.
I am running my coal stoker boiler at summer temperatures of 140 low 160 high with 180 for the dump zone temperature.

SO as of now I have been running water pressures of 1-4 P.S.I.G. on average and I have reduced the coal feed as it has been overshooting on temperature and dumping heat in to the 225 foot single loop which is the dump zone.

I am very happy and the house is warm and I am barely burning 60 pounds of coal per day.

I have been told I cannot do this and it is not possible and the boiler will boil off and become damaged due to the low pressure.

I spent a lot of time explaining that my steel compression tank acts like a municipal potable water storage tank on a hill side elevation that provides a pressure balancing method as I have 84 pounds of water(rounded) sitting in the ceiling 3 feet above the boiler. The five gallons of air space above the boiler also provides the low pressure cushion and as the boiler had overshoot temperatures the pressure sometimes would climb to 8 PSIG and fall back to near zero PSI when their was no heat call or the hold fire timer started the stoker. Since I backed the stoker feed off I have not had any overshoots in temperature today. The B+G NRF 25 circulator is running on speed one with 12 G.P.M. pushing the hot water to the zones split at the Tee and I have no air bubbles in the system.
The cooler water from both zones enters into the return header which is plumber into the boiler sump.

Is there a reference sheet or formula I can download or point to to show how my system is working? I have not looked at the engineering tool box site.

It works and the house is warm.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 20,416
    Pressure is too low -- should be around 5 to 10 psi. Does the air tank have a gauge? It should show about half full. System may have lost air somehow if the tank is full of water -- or have a leak, if the tank is full of air.

    The total weight of water sitting above something is irrelevant -- only the depth. In this case, about 3 feet above the boiler -- which is equivalent to about 1.5 psi.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Gordy
  • leonz
    leonz Member Posts: 682
    Hello Mr. Hall,

    The steel compression tank has a gauge glass and after I lit my first fire the steel compression tank was waterlogged and I drained it down to the proper height on the airtrol valve in the tank-1/3 air 2/3 water and after that the hot water began heating the house and for the last 10 days it has been heating well.

    I will see if the steel compression tank needs to be drained down again in the morning.

    I planned on replacing the 2 3/4" ball valves with 3/4" Milwakee gate valves to assure tight seal.

    It would be extremely difficult to check to see if the domestic hot water coil for leaks but and this is a big but: the steel compression tank was water logged before I opened the 30 year old nibco ball valves to feed the cold water to the domestic coil and to return the hot water coming off the domestic coil to the hot water heater.

    SO I may have to order the 2 Milwakee gate threaded valves sooner than I planned I guess.


  • Jamie Hall
    Jamie Hall Member Posts: 20,416
    Do you have any kind of air removal device on your system? That type of expansion tank must not, repeat not have any kind of air removal device on it. It is not uncommon for them to get waterlogged anyway.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • leonz
    leonz Member Posts: 682
    edited November 2018
    Hello Mr. Hall,

    No the system has no automatic air vents of any type it is closed.
    I had to deal with that type of system when we lost our well and the system pressure had to be recharged several times during that winter(1983) and I was bound and determined to go back to the simpler typeof steel compression tank hung in the ceiling-except the original tank was an open to air saddle tank with a gauge glass.
    The old system worked and worked well heating the two loops.

    I have an Internal Air Separator per Mr. Holohans wonderful drawings assembled in the way he drew them with the back flow preventer as the first control and the pressure regulator as the last control before the water enters the bottom of the B+G Internal Air Separator casting with the top tapping then rising upward to the near horizontal line that then goes to the B+G airtrol valve.

    Its either the two ball valves or the domestic coil that are leaking I guess. I will shut the coil off and see if the tank becomes flooded again in the afternoon when I am home.

    I am beginning to wonder if all the internals on the two ball valves, the back flow preventer and the pressure regulator were
    damaged when the boiler boiled down when I was away taking care of my father. Perhaps they should all be replaced anyway since the hydrolevel 3250 plus triple aquastat did not shut off the stoker boiler when it was supposed to as the low water cut off function was enabled and it failed.

    I may just replace all four components and be done with it as that section of pipe was boiled dry as well and obviously became hot. I wish I had had a B+G McDonnel and Miller RB-122-E Low Water Cut Off on it then as it would have worked shutting off the boiler with out a computer controlling it.


  • hot_rod
    hot_rod Member Posts: 18,190
    As much as you are a proponent of steel compression tanks :) A simple Extrol tank would make some of those tank problems disappear and let you sleep at night, just saying.

    It the tanks keeps water logging that often, somewhere, somehow fill water must be getting into the system?

    .433 psi for every 1 foot of water level, doesn't matter if the open or a glass of water is above you, the pressure is related to the volume not the volume.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • leonz
    leonz Member Posts: 682
    edited November 2018
    A simple extrol tank and air scoop caused a lot of heating problems for us in 1983 due to loss of pressure from lack of water the year my well collapsed and failed and that is why I went back to the steel compression tank system as the old system was physically separated from my water supply and the expansion saddle tank was open to the air and had a level gauge glass in it.

    I can use the 1 inch side tapping's for the gauge glass by just installing the longer gauge glass in two 1" tees with 1" to 3/4"reducer bushings and fill the tank from the bottom 1" tapping with a reducing bushing,pipe nipple and ball or gate valve on the opposite side of the tee on the lower tapping.

    I will not go back to having someone come up and recharge my system with a pail and a jet pump again as they charge $200.00 for a service call plus parts and labor at $85.00 an hour around here now.

    I should have had an open to air system expansion tank system laid out and the shelf built and ready for it as it would have caused no issues for my heating system just as the open to air saddle tank system the house came with which worked faithfully and I should have left it in place If I had known better back then. The stem packing's in the gauge glass would not have leaked either as they would be operating at 1 atmosphere of pressure anyway.

    As for installing a simpler amtrol tank and air scoop I would have to tear everything out and spend another wad of money I do not have to do what you suggest and as I spent over $600.00 dollars on truck repairs today things are not looking good either as I am going to have to spend more money on the truck next week.

    Besides that issue the $10 automatic air vents leak and that is another expense 3 or four time a heating season some years AND they will and do draw air into a hydronic heating system.

    If I was going to do anything this coming year I would just turn the saddle tank into an open to air expansion tank mount it on a strong shelf with a vent line through the roof and and and over flow line to my laundry sink.

    The gauge glass was a little more than 2/3 full of water before I opened the fill valve(the stem packing's leak).
    I found I had a vacuum(pressure gradient is the proper term) of -5 inches of water column on the suction side of the circulator this morning and I added water back to the system and the vacuum (pressure gradient) came back up to zero HG.

    So here we sit at 1,140 feet above mean sea level and I will light the boiler off tomorrow.

    It is a minor inconvenience anyway as it is too warm to run the coal stoker.

  • Jamie Hall
    Jamie Hall Member Posts: 20,416
    Is this steel open expansion tank well above -- at least a few feet -- the highest point in your system? If so... you're fine. That type of system has worked fine for years, and there's no reason it shouldn't just keep right on working.

    It is an open system, so it's nice to have some sort of water treatment in the system water...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 13,095
    Generally 4-5psi at the highest point in the system is what works. In reality as long as it is positive pressure (above 0) at the highest point you are ok. Negative pressure at the highest point make bleeding air difficult.

    That being said a steam boiler with a condensate hot water loop will have no pressure or will have a negative pressure at the highest point if sealed 100% tight and will work ok
  • Gordy
    Gordy Member Posts: 9,537
    edited November 2018
    In a closed hydronic system you need as been said the pressure to be positive at the highest point in the system + 5 psi. Your elevation above sea level is irrelevant. The elevation of the tank above the boiler is not enough to rely on the weight of the water in the tank which is only 15 gallons. Is that total tank capacity? If so then the airtrol only gives you 10 gallons with 5 gallons of air cushion.

    The line to the airtrol should have upward pitch from the internal air separator so the air flows up to the tank. Also need right pipe size.

  • leonz
    leonz Member Posts: 682

    Is this steel open expansion tank well above -- at least a few feet -- the highest point in your system? If so... you're fine. That type of system has worked fine for years, and there's no reason it shouldn't just keep right on working.

    It is an open system, so it's nice to have some sort of water treatment in the system water...

    ====================================================

    Hello Mr. Hall,

    Yes, the 15 gallon steel compression tank(5 air / 10 water) is at the highest point in the system.

    I guess should invest in some steam tabs?? I can always back the boiler drain off the top of the elbow above the boiler and drop them in.

    I guess I should look to see how much chesterton rope packing costs nowadays and invest in a can of it for my place as I have more than 3 boiler drains that may need it along with the 2 gauge glass valves.

    Thanks much Mr. Hall.


  • leonz
    leonz Member Posts: 682
    Gordy said:

    In a closed hydronic system you need as been said the pressure to be positive at the highest point in the system + 5 psi. Your elevation above sea level is irrelevant. The elevation of the tank above the boiler is not enough to rely on the weight of the water in the tank which is only 15 gallons. Is that total tank capacity? If so then the airtrol only gives you 10 gallons with 5 gallons of air cushion.

    The line to the airtrol should have upward pitch from the internal air separator so the air flows up to the tank. Also need right pipe size.

    =====================================================

    Hello Gordy,

    The -5" vacuum(pressure gradient) threw me a curve this morning and I wanted to mention it to the members.

    Yes I have a fifteen gallon B+G(Wessels tank) with 10 gallons of water and a five gallon air blanket above it. The 3/4" copper line that exits the B+G 1 1/4" Internal Air Separator is sloped upward to the 3/4" B+G airtrol valve Per Mr. Holohan and Bell and Gossett installation instructions.

    Thank you all for your help.
  • leonz
    leonz Member Posts: 682

    Generally 4-5psi at the highest point in the system is what works. In reality as long as it is positive pressure (above 0) at the highest point you are ok. Negative pressure at the highest point make bleeding air difficult.

    That being said a steam boiler with a condensate hot water loop will have no pressure or will have a negative pressure at the highest point if sealed 100% tight and will work ok

    =====================================================


    Thank you EEBRATT-Ed,

    Adding water this morning forced a slug of air into the steel compression tank and brought the vacuum back to zero HG.
    I knew I was on the right track for good heating when I came here and registered to be a member.
  • hot_rod
    hot_rod Member Posts: 18,190
    I guess i don't understand how the well had and effect on the heating system. Did the boiler drain back to the well? Isn't is a sealed closed loop system, hopefully with a back flow device or at least a check valve on the water feed. Unless the system has leaks that allows the pressure to drop or the system to drain out?
    So it needs constant, or occasional fill water?

    sounds like you are replacing valves and packings to stop small leaks?

    The pressure on the system determines the boiling point, if it drops to 0 and the boiler runs away on temperature you will boil, flash to steam.

    So in addition to "lifting" the water to the highest point, which sounds like the tank 3 feet above the boiler? The pressure also increases the boiling point.

    Same as a radiator pressure cap on your truck, the few psi or the cap allows the engine coolant to exceed 212F.


    A typical boiler operating pressure of 12 psi, gives you a 240F boiling point. 240 is about where the temperature range on boiler pressure and temperature gauges peg out :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • leonz
    leonz Member Posts: 682
    Hello Mr. Rohr,

    My only thoughts about replacing the ball valves with 2 Milwakee knife gate valves is to simply stop any chance of the steel compression tank becoming flooded again.

    As Mr. Holohan has stated so well in his writing the gauge glass systems on steel compression tanks leak and the best thing to do is shut the valves off then break the gauge glass.

    The gauge glass in my system is filled with water and the valves are shut tight SO.......................................................... I will just do more work on the system when the heating season is over.

    My old hand fired wood and coal system was installed in 1982 with no back flow preventer which was not required then as I understand it nor did it have a check valve. There was only a pressure regulator in the system that fed water to both boilers that were connected in parallel with two circulators one of which was used as the temperature balancing circulator for both boilers which fired the oil boiler when the hand feds fire went out.

    The flat grate stoker I have has a gravity fed hopper and a pusher plate which pushes the unburned coal dropping from the hopper forward across the fire grate which has a perforated floor that allows combustion air to be blown into the burning coal to burn it and the fresh coal feeding into the fire grate pushed the burning coal down the grate and to the end where it falls off into the ash basket.

    The flat grate and angled fire grate stokers operate on a heat call or when the hold fire timer starts the stoker to keep the fire going in the event that there is no heat call.

    The pusher plate stokers used in hydronic heating do not operate very well in warmer weather and the fire will go out if there is no heat call or a continouos heat call load from hot water use.

    In my case the first hydrolevel hydrostat 3250plus triple aquastat that was sent with my coal stoker boiler failed and almost boiled the boiler dry. If it had not been for my wife being home to shut the power off to the boiler...................................................................
    Keystoker had 54 bad hydrostats returned before this and the two bad units I had made at least 56 of them.

    The second hydrostat 3250 plus I was given to replace the first one failed when I was running it on oil and the computer turned the low water cut off function off while I was standing there running the boiler on the oil side!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! After all this I had enough of this foolishness.

    I had a licensed electrician wire my Honeywell L8124L1011 triple aquastat and the McDonnel & Miller RB-122-E Low Water Cut Off
    and run the boiler on oil to make sure it was operating correctly using summer temperatures.

    The Honeywell L8124L1011triple aquastat and the McDonnel and Miller RB-122-E Low water cut off have worked flawlessly since they were installed and tested.

    There are several pictures of a keystoker KAA-8 boiler with its gravity hot water heating system on the forum in a thread about gravity hot water system.

    The traveling grate coal stokers being Axeman Anderson and Alternate Heating Systems which is a copy of the Axeman units operate using an induced draft system to burn the Anthracite rice and buckwheat coal They operate with a heat call and the ash temperature to keep the fire burning.

    These two brands of coal stoker use the temperature of the ash to control the fire as it has a deep rectangular fire bed that is pushed and pulled to bring fresh coal down into the traveling sled through the feed tube and at the same time it pushes the ash forward to the ash cutting knife of the Axeman units, I do not remember if the AHS units have an ash cutting knife or if their design just lets the ash and clinkers it produces fall off.

    The Axeman Anderson traveling sled coal stokers use a traveling sled using a cam arm to move the sled forward and in reverse.
    This design is still used to today.

    The three step sled plate on the Axeman Anderson coal stoker is moved back and forth using a V belt drive reduction gear system.
    The systems cam arm is gear driven using a V belt drive that also rotates the sprockets and roller chain that rotates the coal delivery tube which has an open auger welded in the tube which lifts the coal up through the tube to the top elevation and then it drops into the coal feed tube which has been called the popes hat which is a conical at its base.

    The gap between the coal auger and the coal feeding tube is a nice safety feature that creates a physical break between the coal feed to and the coal in the open auger.

    The gap between the base of the coal feeding tube(popes hat)
    and the highest step of the three steps of the traveling sled allows the fresh coal to drop on the sled as the sled travels back and forth delivering fresh coal to the fire.

    The older Axeman Anderson Traveling sled stokers used a roller chain drive connected sled that was connected to the arm that pushed it and pulled it back with the gear driven cam am which moves the traveling sled back and forth to burn the coal to make hot water or wet steam. The axeman anderson coal stokers have a domestic hot water coil to make domestic hot water.

    The three step plate coal sled in the Axeman Anderson coal stokers allows the fresh coal dropped by the coal auger into the popes hat(coal feed tube) to drop down into the fire box in three steps as it burns and is pulled back pushing the ashes and clinkers forward to eventually reach the stationary ash knife connected to the dry base of the boiler.
    As the dead ash is pushed off the traveling sled by the burning coal and fresh coal following behind it it contacts the ash knife and is cut off and falls into the ash basket.

    The underfed burn pot stokers made by EFM also operate with a hold fire timer with the combustion air pushed through the coal auger tube and it forces the combustion air into the deep coal bed above it. The EFM coal stokers use one electric motor to power the reduction gear system that rotates the coal feed auger and the combustion air fan.

    As the coal is pushed upward into the burn pot the coal volume becomes larger and spreads outward as it rises and the combustion air is forced through the sides of the burn pot and into the coal bed and as the fire gropws upward and outward the coal ashes are pushed away and fall off the edge of the burn pot into the ash basket.
    The several coal stokers had unique features in their design.
    One brand of under fed stoker has a rotating burn pot to allwo the coal ashes to fall off the burn pot and the older larger EFM units had a circular ash knife that surrounded the burn pot and the gear drive system for the round ash knife was operated by a sprocket and cam driven by the systems gearbox.

    The circular ash knife was connected to the burn pot on two pins that were attached to the burn pot directly opposite each other.
    As the gears rotated by the cam arm lifted and lowered the circular ash knife it raised it one side to the top of its arc length and then the cam and gear rotated downward bringing the ash knife downward on the opposite side cutting ash off the opposite side of the burn pot to the bottom of its arc length.

    I keep my coal stoker at summer operating temperatures of 140 low 160 high with a honeywell L8124L011 triple aquastat.
    The dump zone for my home is my single 225 foot heating loop.

    When there is a long period of warmer weather flat and slope grate fire bed stokers fires will go out and it is more difficult to maintain a fire with fewer heat calls.

    Wednesday was first day that this system created a -5 HG Pressure gradient condition since it was installed.








  • JUGHNE
    JUGHNE Member Posts: 10,278
    I service a system with compression tank with sight glass.
    Was losing air thru the top sight glass packing nut.
    Repacked and now is good.
  • hot_rod
    hot_rod Member Posts: 18,190
    Sounds like a fun "project/ heating" system.

    You should be able to get a good, long lasting seal on those gauge glass tubes. I've used them on solar drainback tanks for many years.

    Same with valve packings, seems they are leak prone only when you use the valve often?

    The compression tank should really not need a lot of handholding. It should not need to be drained from a waterlogged condition as often as you say yours has?

    I think two conditions cause them to water log, a tiny air leak, and a constant fill system connected.

    The other concern with plain steel compression tanks is the water and air are in contact with one another. When the boiler heats, air drives out of solution and hopefully is diverted from the boiler to the top space in the tank.

    Over the summer or whenever the boiler cools, the air is re-absorbed into the water, so that air removal process is ongoing with every heat and cool cycle. Air is constantly going in and out of solution driven by both pressure and temperature conditions.

    All the correct parts need to be in place and operating properly in compression tank systems to prevent all the issues you have had.

    Find and seal all leaks, sometimes you need to pressurize to 20 psi or more to find tiny leaks. Be sure you have the proper fitting in the boiler and tank, they work together. Try and get the system to a point where the fill valve can remain off.

    A low water cutoff would be a wise component to have in place.

    Then you can sleep and travel in peace. Relatively speaking :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • leonz
    leonz Member Posts: 682
    Good Morning JUGHNE,

    Have you or any of the members seen a -5 inch vacuum in a closed hydronic system?

    I will be double checking the packing nuts and then go from there as I thought they were tight to begin with.

    I need to find out how much a packing puller costs and how much new stem packing costs today.

    Thanks much,

    leonz

  • leonz
    leonz Member Posts: 682
    edited November 2018
    leonz said:




    Good Morning JUGHNE, good morning Mr. Rohr.

    Well I checked the gauge glass and the globe valves.

    After I closed the gauge glass valves I tightened the packing nuts 1/4 of a turn and no more.
    I opened them again and had a rush of air bubbles pass from the bottom of the gauge glass to the upper valve and back into the steel compression tank.

    I found the upper globe valve handle nut loose and I tightened it down.

    I have left the gauge glass valves open and I have no water leaks or air leaking into the stems of either valve that I can see or hear.

    SO when it gets cold again I will fire up the stoker.

    Thanks for the help.















  • hot_rod
    hot_rod Member Posts: 18,190
    edited November 2018
    You can cause a sub atmospheric condition to exist just by improper component placement. Here is a classic example.

    A system with low fill pressure, 5 psi. A circulator, a fairly benign one :) pumping at the expansion, or compression tank.

    So the pressure differential the circulator MUST create when it spins gets subtracted from the static fill of 5 psi. As you circulate around and scrub away the energy at some point you have a negative pressure condition.

    To know exactly where that happens you need to define the piping circuit and pressure drop.

    IF a high head circ is used, these numbers can get worse.

    It's the reason behind why OWB circulators cavitate themselves to death in a year or two. Low pressure, high operating temperature, and often grossly oversized, high head circulators.

    Pump manufacturers cringe at the words OWF.

    People should not be allowed to touch hydronic systems until they read and understand the book shown below :) IMO
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • leonz
    leonz Member Posts: 682
    Good Morning Mr. Rohr,

    I have a McDonnelland miller RB-122-E low water cut off as the first control on the boiler to shut it off in the event of a boil off.
    The RB-122-E low water cut off is a water contact(conductive?) low water cut off type of low water cut off if I have the terms correct.
    I am glad I have it after my last experience with the hydrolevel controls.

    I will keep every one in the loop when I start up the coal stoker again.

    leonz
  • leonz
    leonz Member Posts: 682
    edited November 2018
    Hello and good evening Mr. Rohr,

    The only forest eater builder that knew what he was doing was Richard the gentleman that owned and built the evergreen outdoor wood and coal boilers.
    These model were the Mighty Sequoya, Whispering Pine, Little Spruce.
    The Big Boss Man and The Little boss man outdoor wood boilers that were insulated and fully lined with firebrick on the top, sides and rear of the firebox and the boss man models had three separate water tanks behind the fire bricks to heat water.
    The design for the firebrick system in all 5 of these models was
    made with the end user in mind. every firebrick could be removed if it was cracked and it could be replaced with simple hand tools.

    All five of these forest eaters could burn wood, corn cobs and coal all in the same firebox as it shaker grates and they used a bypass slide gate to divert the smoke through the metal chimney to allow the boiler to be refilled as needed.

    1
    ====================================================
    if the builders of these forest eaters paid attention to how coal boilers are made and built them that way they would not have such a bad reputation.

    I was horrified one day many years ago when I had one of these people describe his version of the fire triangle which came nowhere near the truth of how the chemical process of combustion occurs.

    You could tell he never stepped foot in a volunteer fire company to learn about firefighting.
    2
    =====================================================

    I used three of Mr. Holohans books; PUMPING AWAY, CLASSIC HYDRONICS and HOW COME.

    I settled on having the circulator mounted above the boiler steam chest to pull water through the boiler to help eliminate air bubbles and to make the job of replacing it easier when the time comes using my spare circulator.
    I am using the B+G 1 1/4" Internal Air Separator and I had 2 boiler drains installed on the 2 cool water returns that are connected to the sump return header pipe.

    Now that the stem packing's in the gauge glass have been tightened up a bit and the gauge glass is fully open showing the proper amount of water in the steel compression tank things will go better once I start burning again when it gets colder.

    3
    ======================================================
  • hot_rod
    hot_rod Member Posts: 18,190
    Well built and clean burning are not always in the same sentence. Until you stick a combustion analyzer down the throat you are merely guessing on how a boiler is burning. The manufacturers, EPA, and independent labs all seem to be on different pages with testing and acceptable emissions.

    The problem with any solid fueled boiler is they don't like to idle. When the load drops off many reduce combustion air and they burn a dirty, O2 starved condition.

    Pellet and coal boilers with feeders may be better if you can decrease the fuel supply quickly as you do the air supply.

    Glad to hear you are making process and getting a better handle on the beast :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Gordy
    Gordy Member Posts: 9,537
    Part of the problem is the solid fuel. Unlike gas, oil, or electricity the btu content Varies wildly with a range of factors. Even wood pellets vary from brand to brand.
  • leonz
    leonz Member Posts: 682
    hot rod said:

    Well built and clean burning are not always in the same sentence. Until you stick a combustion analyzer down the throat you are merely guessing on how a boiler is burning. The manufacturers, EPA, and independent labs all seem to be on different pages with testing and acceptable emissions.

    The problem with any solid fueled boiler is they don't like to idle. When the load drops off many reduce combustion air and they burn a dirty, O2 starved condition.

    Pellet and coal boilers with feeders may be better if you can decrease the fuel supply quickly as you do the air supply.

    Glad to hear you are making process and getting a better handle on the beast :)

    =====================================================

    Hello Mr. Rohr,

    I found when I had my hand fed wood and coal boiler the best way to keep it happy was to use a lot of split wood so that it would burn hard and clean in the process.

    I also filled it half full of standard firebrick all the way to the flue breech taking up half the firebox volume and it sucked the heat up like a sponge and let it back into the firebox gradually to keep the fire hot at all times and I had very little smoke when burning wood and no smoke burning anthracite coal I burned nut and stove size and I also banked the fire soem nights with rice sized coal to hold the fire if it was really cold out.

    A pellet stoker installed for us was going to be well north of $10,000. We would be burning a more expensive fuel than stoker coal and we would be burning twice what we burn in wood pellets versus using coal.

    Its not funny, but if they built these forest eaters to burn better they would not have such a bad reputation and if they used a smaller firebox with lots of firebrick and a firebrick afterburner and a larger water capacity they would be just like the Garn boilers with the induced draft.

    They could be burning Wyoming Sub Bituminous Coal and it would burn cleaner and cost less than anthracite but I do not see that happening either.





  • leonz
    leonz Member Posts: 682
    Gordy said:

    Part of the problem is the solid fuel. Unlike gas, oil, or electricity the btu content Varies wildly with a range of factors. Even wood pellets vary from brand to brand.

    It would have cost us double what we spend on coal to heat our old house too and that is why I wanted a coal stoker, I just made the rookie mistake of buying the least expensive coal stoker in the 130,000-140,000 BTU bracket as that is all I could afford.
  • hot_rod
    hot_rod Member Posts: 18,190
    leonz said:

    Gordy said:

    Part of the problem is the solid fuel. Unlike gas, oil, or electricity the btu content Varies wildly with a range of factors. Even wood pellets vary from brand to brand.

    It would have cost us double what we spend on coal to heat our old house too and that is why I wanted a coal stoker, I just made the rookie mistake of buying the least expensive coal stoker in the 130,000-140,000 BTU bracket as that is all I could afford.
    Bingo! Price is usually directly related to quality with solid fuel burners.

    Some of the stuff coming out of Europe is very engineered and well built. Lambda sensor watching the air/ fuel ratio and constantly tuning the burn efficiency, microprocessor controls, beautiful fit, finish, welds, insulation, jacketing. That quality plus the cost of getting them to the US really drives the price up.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • leonz
    leonz Member Posts: 682
    Good morning Mr. Rohr,

    If our house was better insulated I would have considered wood pellets for fuel more but the cost was not an option to even consider it.

    The coal stoker boiler is running very well making lots of heat now that the weather is colder.
  • Gordy
    Gordy Member Posts: 9,537
    hot rod said:

    leonz said:

    Gordy said:

    Part of the problem is the solid fuel. Unlike gas, oil, or electricity the btu content Varies wildly with a range of factors. Even wood pellets vary from brand to brand.

    It would have cost us double what we spend on coal to heat our old house too and that is why I wanted a coal stoker, I just made the rookie mistake of buying the least expensive coal stoker in the 130,000-140,000 BTU bracket as that is all I could afford.
    Bingo! Price is usually directly related to quality with solid fuel burners.

    Some of the stuff coming out of Europe is very engineered and well built. Lambda sensor watching the air/ fuel ratio and constantly tuning the burn efficiency, microprocessor controls, beautiful fit, finish, welds, insulation, jacketing. That quality plus the cost of getting them to the US really drives the price up.

    And just like all the other alternative fuels coal will find its market.

    Remember when corn was cheap, then wood pellets were cheap?

    At least with wood IF you have your own supply, time, and don’t mind the work it’s the best route you can control fuel price on.


    Speaking of wood pellets I found out that there is a huge difference between pellets for a vertical smoker, and for heating. Pellets for cooking burn far better, and are way more expensive too. Because it’s hardwood. Then I found out that pitboss hickory, Apple,mesquite, or which ever only contain about 30% of the wood advertised on the bag. Want pure 100% the price more than doubles.
  • leonz
    leonz Member Posts: 682
    edited November 2018

    That is what makes me think the least costly way to heat a home, business or greenhouse and make dry steam is with coal especially with an area with no natural gas or using a propain or natural gas boiler as a back up unit.

    I would love to try some Wyoming Sub Bituminous buckwheat sized coal in my flat grate stoker. You would be burning twice as much as it has a lower BTU value but for what it costs per ton you would be able to buy many more tons versus the cost of one ton of Anthracite Coal.

    They both burn cleanly but the Anthracite coal has a higher BTU heat value per ton.

    There is a gentleman in Montana using an AHS S130 traveling sled coal stoker and he replaced a forest eater with the S130 as he can obtain the Wyodak Seam Subituminous coal in his area at a much, much, much lower cost than firewood.
    The Wyodak Sub Bituminous Coal burns down to a very fine ash.

    Here is a link to the video about the AHS S130 coal stoker I mentioned. The link is correct according to what I copied.

    www.youtube.com/watch?v=pLvo3vJxgPs
  • Gilmorrie
    Gilmorrie Member Posts: 173
    The trouble with anthracite is its very low volatility - difficult to get started, except in a boiler designed for it. Sub-bituminous western coal, including lignite, is easier to burn. Lignite would have become coal if it had been left in the ground another million years or so.
  • leonz
    leonz Member Posts: 682
    Hello Gilmorrie,

    I started my fire today in the coal stoker using a store brand of matchlight charcoal. I crushed 6 briquettes with a 4 pound hammer and wrapped the broken briquettes in a half sheet of news print and then lit the bag of charcoal and the coal fire took right off.

    I had old briquettes and soaked them in lighter fluid for several hours and they still did not want to play nice so I opened up the bag of store brand matchlight briquettes and we are off to a new heating season.

    The fellow in Montana with the AHS S130 coal stoker is using it for the first winter season as he sold or disposed of his old forest eater and set the new boiler on the concrete pad that was there for the forest eater. He built the barn around it to keep it out of the weather and he will be insulating the barn as well this year.