Reduce Size of Fire Box

Hi All,

I purchased a DS Stoves Kozy King 300 furnace that ties into my central air ducts last March. Last year I only burned coal for approximately 3 weeks before switching to wood that I already had split in the yard. This year I plan to burn coal most of the winter, but am concerned at how quickly I went through it last year. For the short time I was using coal last year, I was burning approximately 100lbs a day. If I put in a 50lb bag, it would burn in approximately 12 hours. When I put in 100lbs, I just seemed to have a larger fire, but would not get a significantly longer burn time. I have a 2100 sf house that was being heated to as high as 88 degrees while it was 20 degrees outside. My goal is to reduce the amount of coal I burn and keep the house temperature closer to 75-80 degrees. Is it possible to reduce the size of the firebox by lining the perimeter of the grate with fire bricks so that I still have a deep bed? Is this the best way to go about it? I imagine the bricks would fall when shaking the furnace. I am looking for a way to dial down this massive furnace that may be overkill for my house to conserve my coal and keep my house at a reasonable temperature.

Thanks for your help.

p.s. I had the draft blower off and the spinners on the ash door and loading door barely open.

Did you buy it new or used? Sounds like you have an air leak or to much draft. Are the door gaskets in good order? How tall is the chimney? Are you running a barometric damper? Do you have a thermometer to read flue gas temps? You should be able to dial that thing down so something isn't right. Reducing the firebox is problematic and you are not really oversized that much. I run a coal boiler about 3 times my need and have no problems due to it.

Bought it brand new and gaskets are in great shape. I have a barometric damper and it would whistle when the fire was going strong. It's a tall chimney in the center of my house that goes through the basement, two floors, and the attic. I got a magnetic thermometer later on after I had started burning the wood.

I went back to the stove shop I bought it from last winter and the guy sold me a damper for the stove pipe, but I read on here that you don't want to block the stove pipe because of the risk of CO poisoning and took it out pretty quickly.

I'm going to keep reading through the posts on here. Hopefully I'll get it after a little more trial and error.

That damper you put in and took out after reading here, it works okay as long as you install it below the baro...if it were above you could back up exiting fumes and they would spill out of the baro. and into your living space.

Welcome to the forum partner! You've come to the right place. Coaledsweat is right. You should be able to cut back heat output on your furnace by closing your primary combustion air more. A coal fire is easily controlled by how much combustion air you let it have. For example, my furnace always has 80-100 pounds of coal in it. I don't keep less coal in it when its 50 degrees outside or more coal in it when its only 10 degrees outside. When its 50 degrees outside it burns less coal per day of course but I'll only need to add 20 pounds to it at shake and load time instead of 40 pounds when its colder outside to maintain 80-100 pounds of coal total in the coal bed.

Also keep in mind that there is a little learning curve involved with burning coal. It is a different animal compared to wood. You gotta pretty much throw out what you know about wood and learn to burn all over again with coal. Some growing pains come along with it lol. But you'll get it with some experience

Sounds like you have a very strong drafting chimney which is helping your fire burn hot. The barometric damper will help that (its not recommended to use the baro for wood).. A manometer is needed to help you get the chimney draft under control. It measures the negative pressure in the flue pipe and you can then adjust the baro to keep it at a particular pressure.

Welcome DEKozyKing, your stove is a multi-fuel furnace and advertises a re-burn system for burning wood, this tells me it introduces secondary and or outside air to the burn chamber to burn off the gases that WOOD produces. This system is not needed for Anthracite coal. This will also cause the symptoms you experienced last year and as others have said you need to find out where the additional air is entering from and you need a Manometer to measure you draft.
Mike.

A very tall interior chimney is going to suck real hard on your appliance. Get a manometer and read the draft. If your baro is whistling, it is telling you something. You may need more baro to tame the beast. Also, don't run the baro when burning wood. Creosote will build up on it and it won't work properly and you risk feeding a chimney fire with fresh air from the room.
What is the temp of the flue gas? Above 125-140* at idle and your coal is just going up the chimney.

You have received good advice so far so I will only add that once my temps start creeping up I know I need to redo the seal on my ash door. I can run my stove body temps down to about 170 F with good seals and have everything be stable. It can run down to 150 F but things get twitchy that low.

As noted above I keep mine full of coal and only adjust the air to change temps. For really low stove temps I will move from nut to pea coal because that also slows down the air moving through the stove, but I don't think that is an option for you.

SD

as a DSM stove owner / operator connected to a chimney exactly like yours I can support the advise that you get a good manometer and find out just how much draft you have.

i can assure you it's HIGH to VERY HIGH and you will need to find the dampening devise or devises that will allow you to bring it down to no more than the DSM rec. level.

it's just as certain that the high draft you have is exploiting even a very small unintended air entry point. the DSM stoves are well known for very precise burn and heat control when everything is as it should be.

good luck,
steve

DEKozyKing wrote:Hi All,

I purchased a DS Stoves Kozy King 300 furnace that ties into my central air ducts last March. Last year I only burned coal for approximately 3 weeks before switching to wood that I already had split in the yard. This year I plan to burn coal most of the winter, but am concerned at how quickly I went through it last year. For the short time I was using coal last year, I was burning approximately 100lbs a day. If I put in a 50lb bag, it would burn in approximately 12 hours. When I put in 100lbs, I just seemed to have a larger fire, but would not get a significantly longer burn time. I have a 2100 sf house that was being heated to as high as 88 degrees while it was 20 degrees outside. My goal is to reduce the amount of coal I burn and keep the house temperature closer to 75-80 degrees. Is it possible to reduce the size of the firebox by lining the perimeter of the grate with fire bricks so that I still have a deep bed? Is this the best way to go about it? I imagine the bricks would fall when shaking the furnace. I am looking for a way to dial down this massive furnace that may be overkill for my house to conserve my coal and keep my house at a reasonable temperature.

Thanks for your help.

p.s. I had the draft blower off and the spinners on the ash door and loading door barely open.

you got a bit of an eye opener. huge stoves with big fireboxes, you will be amazed at how economical they are not. at 100 lb./day that would be 1.5 tons a month, or around 6 tons a year if burned Nov-Feb 4 months. add another 1/2 ton for shoulder months heat. at the current price of 200/ton at the source, that would be 300/month for coal heat. there are many heating their homes with city nat gas and hot water too, for less or equal that. see what happens ? you can easily put in alternative heat that costs you more than standard heat and it becomes a lose-lose deal, because the stove also has to be lit, fed, raked, ashes taken out.

reduce average indoor temp to 70-72 degrees. the best way to heat is, put a stove in the actual living quarters such as LR or kitchen, the floor the stove is on is always the hottest. if you reduce the size of the firepot, you will also reduce the heat and temp level in the house as well.

perhaps the fire just needs some judicious tending and dampening ?