Several of my design goals were verified during this first test.
Notice the 18 small holes pointed to by the red arrow in the photo below. Those are the exhaust holes for the burner gases, and collectively, the area of all the holes is approximately 3 times the area of the blower output. During operation, the air blown in expands greatly during combustion, then cools and contracts as it transfers its heat to the boiler tubes. Carefully placing my hand into the exhaust stream revealed the flow to be slow and gentle. This first test has verified the exhaust holes collective area is large enough such that the exhaust gas flow is not restricted.
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Second goal achieved (so far). Clearly, the more BTUs transferred from the combustion gases through the copper tubing and into the water yields greater efficiency; a good indication of this efficiency is to measure the exhaust gas temperature as it come out of all those little holes. Although I neglected to have a thermometer within easy reach, I did place my hand into the flowing exhaust gas stream and noted it was barely warm,....honestly, I think my cat is hotter than the exhaust gases. Exhaust temperature will no doubt change when steam flow is partially blocked allowing pressure to build, and when the burner is operated at higher levels, but this first test is very encouraging.
Finally, during the one minute the YouTube video was recording, I was slowly closing the water valve until I saw no more liquid water dripping from the steam output, as can be seen in the video; at which time I walked around and turned off the boiler. Once I put down my camera/cell-phone, I pulled off the quick-disconnect from the water faucet to observe the flow rate. I was quite surprised that such a large amount of steam had been generated by what I perceived to be a rather low rate of water flowing from the faucet, and in a senior moment of forgetfulness, I instinctively reached down and turned off the faucet. What I had planned to do, was place the near-by bucket to catch the water coming out of the faucet and time how much water was flowing out of the faucet,...oh well, no worries, that measurement will now wait for test #2
The final lesson learned from this test: as long as I'm using water as the working fluid, and not R123 or any other organic fluid, the required feed pump needs a much smaller flow rate than is required for R123.
I will talk about required flow rate in a separate post.