Maintaining an Even Oven Temperature in a Wood Cookstove, Part 4

What I Do

This post is intended to be an accurate and detailed account of what I do to keep the temperature of my wood cookstove ovens steady.  Remember, however, that every stove and every chimney is different, and it is entirely possible that for another wood cookstove user, none of this information will prove useful.

The first steps in baking in either of the cookstoves that we currently use is the same: start the fire.  The process of establishing a steady fire should result in a bed of coals being present in the bottom of the firebox.  A bed of coals serves to prevent the oven temperature from fluctuating drastically, but I find that coals alone provide insufficient heat for baking.  Furthermore, it doesn't take long--especially in the Margin Gem--for the coals to "ash over."  "Ashing over" is my own term to describe the process of the outer layer of a glowing coal becoming ash as combustion of the burnable material is totally completed.  If you've ever burned charcoal, you are familiar with this situation and know that the bed of charcoal needs to be stirred a bit when you can no longer see the glowing coals for the layer of ash that has accumulated on their outsides.  Once coals have ashed over, the heat which radiates from them is significantly diminished.

Before I go on with the next steps, it is important to understand another characteristic of the wood-fueled fire: the amount of heat radiating from the fire is determined by the amount of surface area of the burning firewood.  The greater the surface area which is burning, the greater the heat radiated.  Suppose you have a log which is four inches in diameter and eighteen inches in length.  If that log is put into the firebox and ignites, the maximum surface area which will be radiating heat is approximately 251.2 square inches.  Now suppose that the same size log is split into four smaller pieces and all four pieces are put into the fire at once.  The same volume of fuel has been added to the fire, but the surface area of those four pieces is now 539.2 square inches.  Thus, the four smaller split pieces will burn hotter than the one whole log, but they will not burn as long.

This whole geometry lesson is important because once you have established your bed of coals, you control the temperature of the oven by adding appropriately sized pieces of firewood to keep the oven at the temperature that you desire, using larger pieces for cooler temperatures and smaller pieces for hotter temperatures. 

Managing the baking fire in the vintage Riverside cookstove and managing the fire in the new, airtight Margin Gem cookstove are two distinctly different processes, so I'd like to talk about the two stoves separately now.  We'll start with the Riverside.  Maintaining the oven temperature in the Qualified was basically the same process, by the way.

A small log burning in the Riverside Bakewell.

The firebox on the the Riverside (and the Qualified) is quite small compared to wood stoves which are built for heating.  Once the fire has a well established bed of coals and the oven is near to the needed temperature, I would add one fair-sized split piece or whole log--there isn't room for much more--for a moderate oven.  This needs to be quite dry and ready for burning.  This should be sufficient for keeping the oven at a moderate temperature.  Once this log has perhaps burned to about half its useful life, I would add another piece of similar size.  While the second log is igniting, the first log is finishing its combustion.  This keeps the second log from suffocating or significantly cooling a fire which has completely gone to coals. 

If a hot oven is needed, then I would continually fire with smaller pieces of wood which would be added at more regular intervals.  Since the firebox is small, large pieces are not really an option, anyway. 

Riverside Bakewell firebox full of small pieces of wood.  A fire
like this would be needed for a hot oven.

Managing the oven temperature on the Margin Gem has proved to be quite a bit more challenging for me than I had expected.  We have used the Margin Gem exclusively for our baking since August of 2012.  I haven't ruined anything, but the Margin Gem's firebox operates on an entirely different principle of combustion than that of older style stoves like the Qualified and the Riverside.  Basically, in the Margin Gem, air enters the firebox above the fire rather than from beneath the fire.  Also, since the firebox itself is so much larger than the Qualified or the Riverside, I've discovered that adding only one piece of wood at a time is not sufficient for keeping the oven hot.  Instead, I always have to add at least two pieces of wood at a time.

Two pieces of wood burning in the Margin Gem cookstove.

In the Margin Gem, it has been my experience that more logs or split pieces make a hotter fire, and fewer makes a cooler fire.  However, I have encountered some challenges.  If the bed of coals in the firebox is quite deep, it can sometimes take quite a while for wood which has just been added to the fire to begin burning, and the oven cools because the new wood is preventing the heat from the coals from moving through the stove. 

I mentioned this to Mrs. Detweiler, an Amish acquaintance who has a Gem Pac cookstove.  She understood exactly what I meant and advised keeping the bed of coals to a minimum and making sure that they were frequently stirred down.  This causes the firebox to operate more like older style cookstoves where the oxygen enters the fire from beneath.  This certainly works, but it is not always easy to get the coals stirred down sufficiently.

What seems to work best is to make sure that I have plenty of small pieces of wood available when I am baking because they offer a more controllable heat.  The small pieces not only burn hot, but they burn quickly which provides an added measure of control.

I also have to remember that I cannot let each load of wood burn quite so far into its total combustion time as I would have in the Qualified or the Riverside before adding more wood.  Because the ignition time on new wood is longer in the Margin Gem, it is important to add the new wood to the fire sooner than what I was accustomed to.

I have also tried filling the firebox to the top and then controlling the amount of heat which the fire emits through the use of the drafts.  This method has not been as successful as I would like because the fire tends to eventually burn quite hot.  I'll continue to experiment and update the blog as I learn more.

Hmmmm.  I feel that I must again say that baking in a woodburning cookstove looks a lot more complicated in print than it is in real life.  Don't let any of these posts intimidate you.  They are merely well-intentioned help for those wondering how to manage the heat of a cookstove.  Each wood cookstove cook will develop his or her own techniques which will work best for each stove.  The biggest key is to pay attention to what gets results and to be observant.  Besides, the rewards of learning to bake in a woodburning cookstove are great.  For some reason, when I cook on a modern range anymore, it just doesn't feel like cooking.  That sounds funny, I know, but I can't describe it any other way.