PsychHike,
That stove without a doubt will warm a 13x13 room - in fact it is going to have you in your underwear and a t-shirt when we figure out what is not working right. My 3CB is in a 20x14 room with cathedral ceiling and it keeps it in the upper 70's even burning lower btu woods. My reload times vary from 3 to 6 hours depending on the outside temps - I only need to run it hard and reload every 3 hours when it stays in the lower 20's or below. It would even keep the rest of my comfortable except much of the heat is trapped in my cathedral ceiling and my walls/floorplan is wonky. My point being this stove is perfectly adequate and a quality stove so we just need to figure out what is not working right in your specific case.
My jotul can get UP in temp to 550-600' but it stays there for about 30-45 minutes max, then the temperature plummets from there until it goes out -
This stove has to be operated a specific way that may not be obvious. I received a lot of advice here, took me a bit of time to actually absorb the advice. Here are 3 key things about this stove:
1) make sure the lid is on good. It is held on by 2 set screws. Use an allen wrench to loosen, remove it and inspect the gasket and look at the impressions made in the gasket by the contact with the body of the stove. Make sure it looks like the gasket is sealing properly and there is no excess cement interfering. Also look on the lid and inside the stove for any black, sooty areas around the lid as this would indicate an air leak. An air leak from the lid can disrupt the optimal air flow and several of us have found simply reseating the lid made an improvement.
2) I thought my wood was dry because it looked like a dry as a bone. I was convinced it was dry because I was standing there looking at this dry split and thinking these guys online were crazy for challenging me over my wood. My first year my wood was not dry. I finally learned it was not dry by splitting a split open and I could tell it still held moisture. I bought a cheap moisture meter which confirmed it. My burns really improved my 2nd and third year once I got head in stacking my wood and had wood that was split and drying for 2 seasons.
3) Dampening down. This took a lot of discipline on my part. This stove wants to be dampened down in three steps, not two. You said you moved the lever to half way - I suggest this is wrong. Let the initial load come up to 500-600 and then dampen it down 1/3. It has to 'stabilize' and continue to burn energetically another 10 minutes or so and likely go up another 50 to 100 degrees, then dampen it down another 1/3. Now it will burn less active but still be burning good, stove it putting out heat and some secondary burn occurring. Give it 5 to 10 minutes, then fully close the damper. Your secondary burn should kick in and you will see this as jets of flame appearing from those holes in the top of the firebox. This process of closing it down by thirds takes about the first 30 minutes of a 3 to 4 hour burn cycle. After a season or so of succesful burning you will get better at understanding where your stove is and be able to make slight adjustments depending on how a given load of wood is burning.
Tell us about your wood. What type? How do you know it is dry? How long since it was cut? How long since it was split. Was it stacked where the sun and wind could dry it all season?
And tell us how much you put in your stove? Are you packing the firebox full or is there a gap between the top of the wood and top of the stove? How about a pic or two of your loaded firebox?
Your description of it initially getting hot, but quickly cooling off after you start to damper it down sounds like what I experienced by dampening it down too quick. And it can also be caused by wood with too much moisture. You can get wet wood burning pretty hot with lots of air, but it won't stay hot as you lower the air supply.