Tuesday, January 29, 2013

Maintaining an Even Oven Temperature in a Wood Cookstove, Part 2

Variables to Consider

The contractor whom we chose to refurbish the walls in our living room and dining room a few years ago used to run a country inn where she had cooked on a vintage wood cookstove.  Both of us preferred cooking on our woodburning ranges over a modern stove, and we had great conversations where we compared notes.  I said to her that one of the reasons that I liked to bake in the woodburning range better than the electric stove was because I felt like I was in control of the woodburning range.  

"I know exactly what you mean," she agreed, "but not just anyone would understand what you just said."  

I've thought of that conversation several times over the years, and though it might seem strange to the layperson, I think that it makes all kinds of sense to experienced wood cookstove users.  When you use a modern oven, the only control that you have over that oven is the thermostat.  When you bake in a woodburning cookstove, you actually have a broad array of things that you can do to control the heat of your oven.  Thus, maintaining an even oven temperature is entirely dependent on the knack and skill of the baker.  That said, it seems appropriate to discuss several variables that are present when one is baking in a woodburning cookstove.  

The information below might seem intimidating in its scope, but my aim is to equip the reader of this blog with an arsenal of information and techniques in order to make the wood cookstove baking experience as easy and rewarding as possible.  As I said in Part I of this series, baking in a wood cookstove is not difficult.  It just looks that way in print.  Fear not!

Variables You Can't Control

These aspects can affect your baking experience.  You can't control them, but you may need
to take them into consideration as you evaluate what is happening while you bake.

1. Weather  This usually isn't a significant concern, but I would be remiss if I didn't mention it.  Cooler weather creates a better draft in your chimney and will make your stove respond better to what you do to control the fire.  Warmer weather reduces draft and can make controlling your fire a bit more challenging--though certainly not impossible.

2. Food You Are Baking  Sometimes you haven't got a choice about what it is that you are baking, and what you are baking will determine the temperature that you need your oven to be and for how long.

Variables You Can Control

This is a list of what is up to you to govern to make your baking experience successful.

1. Food You Are Baking  Sometimes you have got a choice about what you are going to bake.  If you are having trouble achieving a hot oven, but a moderate oven is attainable, make Danish pastry instead of cream puffs, or a cake instead of baked Alaska.
This seems to be the most appropriate place to also point out that some baked goods will demand that you open the oven door more frequently during the baking process than you would for others.  Cookies, for example, involve frequently accessing the oven at shorter intervals of time than you would for a cake or pie.  Each time you open the oven door, experts estimate that the oven loses twenty-five degrees of heat.  In a modern range, the thermostat cycles to bring the oven back up to temperature; with a wood cookstove, you've got to manage your fire in such a way as to compensate for the additional heat loss.
2. Fuel  When you are baking, I think that it is best to have a variety of woods available for use.  Different types of trees yield firewood of different densities, heat values, and burn times.  If all of the firewood available to you is the same variety of tree, do not despair.  Having different sized pieces of the same wood usually offers quite a bit of control over the fire too. 
In the future, I would like to write a few posts about firewoods, but for now I'll just touch on a couple of points:

a) Small diameter, lighter weight pieces of wood burn very hot, but don't last long.

b) Pieces with larger diameter and greater weight burn hot, but less so, and they last longer.

In the picture below, you can see the variety of firewood pieces that were in our woodbox last night.  We had a combination of cottonwood and elm and something else that my folks brought us that a storm brought down at their house.  You can see that we had pieces of various diameter which were whole as well as split.

Different varieties and sizes of firewood available for baking.

3. Distribution of Fire in Firebox  I know that this sounds funny, but it is important.  If your fire is not spread evenly in the firebox front to back, the oven will not heat evenly either.  Thus, if the hottest part of your fire is in the back of the firebox, the back of your oven will be hotter than the front--and so on and so forth with wherever the hottest part of your fire is located.

A picture from the post about grilling on a cookstove.  This
shows a time when I purposely did not distribute the fire
evenly in the firebox.  At the time this photo was snapped,
the front of the oven would have been hotter than the back.

4. Oxygen Supply to the Fire  For combustion to occur, oxygen must be present.  In general, the more oxygen supplied to a fire, the hotter the fire burns.  This is why the old blacksmith forge was fitted with a hand-cranked fan or bellows to rush oxygen through the coals and create the intense heat needed to make metal malleable.

To cool a fire in a cookstove, you decrease the oxygen flow by closing the drafts.  To cause the fire to burn hotter, you increase the oxygen flow by opening the drafts.  HOWEVER, there is a caveat: opening the drafts too widely will make the fire burn hotter, but will also allow extra, unused fresh air to circulate around the oven and will result in a lower oven temperature.  This "point of diminishing returns" can only be learned with experience, and because weather conditions affect draft, it is also mobile.

5. Amount of Unheated Air Circulating Around the Oven  If the fire is too hot for the baking temperature that is necessary, permitting cool air to circulate around the oven will keep the oven temperature from getting too high.  Some stoves are equipped with a "check draft."  This is a draft which is located above the fire so that, when opened, cool air is permitted to enter the stove above the fire and around the oven.  Fellow cookstove user katlupe has a great picture of her Jewel cookstove at this link.  The check draft is the three little openings on the pouch feed on the left side of the cooktop.

I've never had the privilege of cooking on a stove that was equipped with a check draft.  However, I've read that a similar effect can be accomplished by simply tipping open a few of the cooktop lids above the oven, thus permitting the cool air to circulate around the oven in the same fashion as a check draft is designed to do.

6. Amount of Fly Ash Above the Oven  Since most wood cookstove ovens heat from the top down (see the Part 1 of this series), some ovens tend to cook foods thoroughly on the top, but not on the bottom.  One way to help make sure that the oven is of more uniform temperature from top to bottom is to leave a layer of fly ash resting on the roof of the oven beneath the cooktop.  Fly ash is ash that floats up from the fire and either gets stuck somewhere in the flue path of the stove or travels up the chimney.  Except for when I had to move the Qualified range, I never scraped away all of the fly ash from above its oven in the entire time that I used that stove.

7. Use of Baffles in the Oven  When I was in college at Iowa State University in Ames, I once visited the kitchen store in downtown Ames which sells AGA cookers.  The sales lady there explained to me how one can use the "cold plain shelf" in the AGA ovens to create two different baking temperatures in one oven.  Covering an oven rack with a piece of aluminum foil produces the same effect in a wood cookstove oven.

8. Location of the Food in the Oven  Foods placed closer to the top of the oven will cook differently than foods placed nearer to the bottom of the oven.  This is true in modern ovens too, so this is nothing that would surprise the experienced cook.  It is also a variable that the wood cookstove baker has at his disposal.

I'm always stressing to my students that writing is a process of revisions upon revisions, and I'd just like to take this opportunity to say that readers of this post might want to occasionally revisit this location in the future.  I have a sneaking feeling that I have inadvertently left something out, but I can't think of anything that is missing at the moment.  If I find that something has been omitted here, I will add it in the future.  Also, if you are a wood cookstove user, please take advantage of the comments section to tell me about other variables which I have neglected to include here.

Now, I realize that I still haven't actually told you what processes one might use to maintain an even oven temperature.  The next two posts on this topic will provide you with that information, I promise.

Jump to the next post about "what other people do" to maintain an oven temperature here.


  1. thank you soooo much for this information

  2. What a wonderful blog & resource! Don't know when I've ever seen such good information all in one place.
    Best wishes.
    Granny Miller

    1. Thanks, Granny Miller. After looking at your site for the last several months, I'm honored to have you stop by my blog! Feel free to chime in with a Waterford Stanley point of view anytime.