It's hard to control the fire. The house is usually 75. If I don't put on 3 shovels, I have enough heat loss up the flue so that the water doesn't get warm enough. I do not have unburned coal. The black pieces in my bed aren't coal; they're shale. Other than letting it go out and restarting, I don't know how to manage the fire on less than 3 shovels. It only takes me 2 minutes to restart, so lately, I've been only burning at night and restarting in the afternoon. The house only loses a few degrees.
As for wood, I have another door into which I drilled about 50 1/4" holes. This lets air over the wood bed and significantly reduces the amount of smoke. This works great when the damper closes and the fire starts to smoke. Last year I never switched doors and used it for coal too.
I don't bother trying to use the grates. I use the pipe as stated in the previous post, to break up the bed.