Being a slow learner, or to jump on the political boob of the moment, a fire retardant, it took 'til this 3rd burning season to "tune" my burn with storage and I'm now learning to "tune" stack temp with burn and storage. Although I have not yet collected data to verify the stack temp experience, I believe that 1) storage can make the burns more efficient, although for the same plus a little different reason than mentioned, and 2) adding a few temperature meters and data logging with charting has the potential to really improve on (1).
I think 3 temperature meters/gauges (preferably digital) will do the trick: one at a point about at the bottom 1/3 of the storage tank, a second at the bottom of the storage tank, and a third to measure stack temp. If you have less than 1000 gal of storage, might put one meter at the 1/2 point rather than bottom 1/3 point. These can be done with mechanical thermometers, but a bright digital display is barely more expensive and you can see everything in the same place and at a glance. More gauges might help and certainly make everything more interesting if they randomly blink in different colors, especially for the disinterested significant other who would rather do something mundane like read a book to increase one's intellectual prowess.
I use pressurized storage, and you may have to adjust the numbers a bit if you use an hx and experience somewhat lower temps. The two tank meters at a glance will tell you the status of tank charging and let you know whether you should add more wood or let the current load burn to finish in order to fully charge storage. When the meter at the bottom 1/3 starts to move up, say above 160F, the bottom meter likely will still read quite low, but you know it won't take too many more btu's to charge to near capacity. Probably should not add any more wood, or if you have a full load burning with little demand, you may have more btu's than your storage can accept. The bottom meter instantly reports total tank charge status, but as the bottom may cool quickly, the meter at the bottom 1/3 may give a more accurate tank charge status.
The digital stack temp meter really gives you a good picture of your burn. The benefit here is that you can easily tune down or accelerate your burn to meet demand or to instead focus on burn btu transfer to water efficiency. For example, I have learned that at about 465-480F stack temp the Tarm is putting out about 80-90% of rated capacity. At stack temp of about 515F I'm getting about 100% of rated capacity. At stack temp of about 400F, I'm still getting good gasification but output is much less, burn is longer. I use the chain turbulators, so these numbers likely will change if no or other turbulators. All of this on the Tarm is controlled mostly by draft fan speed. Oops! - need to also consider a speed control on the draft fan; I'm working on an automatic one but a manual one works pretty good also.
Based on demand/need, by slowing the burn down and still maintaining good gasification, I believe you will increase total burn efficiency and maximize btu transfer to water as a result of fewer btu's going up the chimney. At some point I may focus on trying to measure this, but there really are a lot of variables at work here.
Data logging and charting adds the ability to see performance over a time period without staring at the meters for hours on end, which really is quite entertaining because the brain is moved into numbed oblivion, an altered state that some use other means to achieve. The chart verifies observations and puts them into perspective.
There any many ways to accomplish this. Look at the
Data Logger thread to get some ideas. For me, since I had a laptop PC with a program to format collected data, total cost, including a box in which to mount everything, was about $155.