Hearthstone Wood Stove Ash/Coals Problem

CTcountrylife Posted By CTcountrylife, Jan 26, 2013 at 1:55 PM

  1. CTcountrylife


    Jan 26, 2013
    Northwest, CT
    Hello Folks,

    I live in a rural area in CT. We bought an old colonial home (1754) over a year ago. We have 5 fireplaces within our home's center chimney, and our largest one, we have a very sizable Hearthstone wood stove in. It's a Hearthstone I, probably made sometime in the 1980's. We have oil heat, but only use it when the temperature dips into the single digits. (Attached is a photo of the wood stove.)

    Our problem is that, after a day of burning, our stove is producing almost no ash. Instead, coals pile up. After a night of sleep, I come downstairs to find the stove about 300 degrees and full of coals (mostly black) with a very thin layer of whitened ash flakes. It burns about 400-450 degrees typically. I end-up walking an ash bucket full of coals out to the back of the property each morning just to make room because the coals won't burn off. I must note, that I swear the wood burns off better during the day than at night... or maybe that's when I finally start having the pile of coals build-up.

    So far, I have checked: We are burning dry seasoned wood. We have a roofed shed dedicated to our wood supply. The newest wood that we have been burning is white and green ash that was cut down early fall (but it's ash, and it's dry and 4 months old). All of our seals are good. Both the side and front door gaskets are good. The damper plate was off when we moved in, I reattached it. I installed a bottom door handle to the front door to ensure a great seal. I check that the secondary air source was free of clogging. We have no problems with smoke coming back down or out of the stove.

    We did not have this problem during our first winter. We recently had a chimney sweep install an insulated liner ( 8" diameter) from the wood stove to the top of the chimney in an effort to protect the life and integrity of the 258 year old brick chimney. Could the now limited flue space affect the burning? I assumed that an 8 inch liner was pretty standard for wood stoves.

    After all of my research and trying different combinations of damper plate open/closed, secondary air ports open/closed, etc, I somehow believe that the wood stove just isn't getting enough air. Our home has terribly old windows with very modest storm windows and plenty of drafty doors also. We are the farthest thing from the newer "airtight" homes. So, I believe that that rules out any potential issues with pressure differences.

    The stove has two secondary air ports. One is on the back, with a lever seen in the back left corner. The second is on the right side of the stove (pictured without the animals). Should either or both of those be open or closed during the wood stove's burning?

    I appreciate any help. We have a baby coming in another month and we just want to find some peace of mind knowing that we are burning efficiently and our heating system is working correctly.


    Attached Files:

  2. begreen

    Staff Member

    Nov 18, 2005
    South Puget Sound, WA
    Welcome Kevin. The back port with the thermostatic control is the primary air. The thermostat is probably not registering correctly because the stove is set in the fireplace and the retained heat of the fireplace is keeping the thermostat too warm. I think you are going to have to operate it manually and give the fire more air. The side port is the secondary air and should be kept open. How is the secondary burn tube looking inside the stove?

    PS: 4 month ash is probably contributing to the coaling issue. It may feel dry on the surface, but I would bet there is retained moisture still in the cells of the wood.
  3. Backwoods Savage

    Backwoods Savage
    Minister of Fire

    Feb 14, 2007
    Welcome to the forum Kevin.

    You have nailed your problem without knowing it. Right up front I will tell you that you have a problem with your wood. You also evidently have listened to some old wives tales. "...but it's ash, and it's dry and 4 months old."

    Sorry, 4 month old ash is not good fuel. Ash indeed is an excellent firewood and we've burned mostly ash for the past 10 years because all our trees are dead from the emerald ash borer. Even though our trees are dead, we dare not cut a tree and try to burn it right away. It don't work. No matter what you say, that is not "seasoned" wood. That is green wood with lots of moisture in it. Until we learn how to burn water you should make the effort to get your wood at least a year before you need to burn it. That is a year from the time it has been split and stacked.

    On the stacking, it works best to stack it off the ground but out in the wind; not in a shed. The sheds are nice but are poor places for wood to be drying. What we do is every October we move enough wood for the winter into our barn so that we don't have to pick through the snow and ice to get it. But our wood has usually been split and stacked for 3 or more years! Why? Because it burns much better and we get more heat from less wood. In addition, we don't worry about our chimney. Sure, we check it occasionally but we haven't cleaned it for 4 years now and there is no creosote in it. That is because we burn dry wood.

    But let's go back to the coaling problem. It is the wood that is causing it but you can work around it to some extent. I hate to think about taking coals from the stove because there is a lot of heat in them. What we do is to watch the fire. Just before we are down to all coals, that is, we can still see the shape of at least one log, we then open the draft full. This will hold the temperature up in the stove while burning down the coals. Also, I hope you are not taking out all the ashes with the coals as you should have 2-3" of ash in the bottom of the stove.

    Good luck.
    CTcountrylife likes this.
  4. CTcountrylife


    Jan 26, 2013
    Northwest, CT
    Thanks for the quick and informative input. Both of your comments on the ash not being seasoned enough make a ton of sense. I am at the point where I have already cut and stacked wood for winter '13-'14. So, I don't believe that this will be a problem again next year or in the future.

    So, the less than adequately seasoned ash is adding to my problem. Regardless, I am pretty certain that stove and user operational issues are to blame for a good part of our issues. When I have burn piles outside and dispose of all types of wood (green, rotten, etc), I still produce mostly ash at the end of the day. So, when given green wood to burn, some level of ash can eventually be produced, even if the fuel is poor.

    So the lever attached to the primary air is the thermostatic control. It should open and close the primary air by itself as the temperature of the stove changes. Your suggestion is that with the stove tucked away in the fireplace, the trapping of heat would change its effectiveness. I should note that the cable from it has been broken since we moved in. I attached a coat hanger so the primary air can be controlled manually at least. During our first winter, I kept the primary air propped open all the time. (I don't really have a reason to stop our fires since the stove is our primary source of heat. They just burnout.)

    So far, I've learned that the secondary air should stay on during the wood stove's operation. I have read that that is to bring warmed air to the combustion chamber. How should the primary air act in regards to the states of burning? If one wants to shut down the fire, it seems that one should close it. If one wants to burn furiously, then one opens the primary air. Is this correct? Also, if our primary air opening is tucked away in the back of the fireplace, a very warm and confined air, does the air pressure/accessibility or air temperature affect how the primary air functions?

    Onto the damper plate... We have a non-catalytic wood stove. The wood stove is about 32 inches long and our damper plate is only 18 inches long. I installed the plate and realized that the damper plate cannot stop all air from flowing out. It shuts down the flow of air to the middle/front section of the stove and forces the air either back down into the chamber in a rolling effect or towards the sides of the damper plate into a much narrow area for air to retreat from the stove. Should the damper plate be closed during peak operation to increase the combustion chamber's efficiency?

    Is it agreed that installing an 8 inch diameter insulated liner is helpful to the stove's future efficiency?

    So, please correct me if I am wrong. Given our stove as it is:

    We should keep the secondary air open all of the time. We should keep the primary air propped open while we burn since its thermostatic control does not work currently. And we should keep the damper plate down to increase combustion efficiency.

    Attached Files:

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