After writing a similar post on 1/15/2012 I find myself saying basically the same thing, after a -10F night the boiler has kept up. Additionally except for a 12 hour period when I made some boiler modifications the boiler has run continuously for 14 days. There are several differences however. The software is 100% better and controlling the temperature to within a few degrees. The burner is now a waterfall type burner that is much safer and runs more consistently. The hopper and auger setup is much more consistent and dependable as a worm and worm gear than the chain and sprocket setup from last year. Most significantly the burner has proved it can run on chips as well as pellets. During these colder nights it is more difficult for the burner to keep up with chips because of the density differences. The chips are much less dense and because of this the auger must feed significantly more of them. The auger motor may need to be changed to accommodate this burning however during weather that does not require so much energy the chips will burn just fine. I could have easily burned chips for most of December with no issues if they had been dry enough. Which brings me to my second topic.
A test plan. I have taken the Holidays off but it is now the new year and time to make some constant progress. To facilitate the test plan I want to make some incremental improvements in the software. The first change in the software is to gather more data to make better decisions. To do this I am going to first add the date and outside temperature readings to both the LCD display and the data collected. By knowing these I can correlate the feed times to temperature and see how close a relationship between them exists. Next I would like to total the run time of the auger per minute and correlate that to both outside temperature and fuel usage. Armed with this additional data I can then make various burner modifications and see the differences if any graphically. The data is good now but could be better. As you can see from the data below the software is not working properly now. The derivative portion of the formula is not contributing at all. This needs to be fixed in the software.
Last night I went over the remaining issues with my girlfriend. So here is the list and the possible fixes and approaches to each item.
1) Smoke. There is still some remaining minor smoking issues. Possible fixes, better caulking, stronger fans, a wind baffle, burner redesign? Pipe cleaning? I think I will start with a wind baffle and some better caulking, next furnace will have a better gasket design. I also have ordered a Magnehelic to help determine the normal static pressure so that a baseline can be established and tested against. The boiler is working so ordering fans without more facts would be a expensive trial and error process.
2) Feed issues. There continues to be an occasional feed issue. So much so that today I am going to take the burner off the boiler and see if I can determine the binding issue. Possible solutions? Increase in torque, already ordered more sprockets.
3) LCD issues. The problem has been traced to the relay and I think needs some old fashioned power regulation, no doubt involving a capacitor to remove the spike when the relay is released. Possible fixes, ordered an LCD backpack to free up some IO and also allow only one power and ground to go to the LCD.
4) Hopper Extension. 3 bags per day means a bag every 8 hours, no all that conducive to being able to leave for a day long event.
5) Data logging. Tuning the machine is always the fun part and so dependable data logging needs to happen. I ordered a SD card writer. This should allow the internal Arduino software to work with the card independently of Windows XP which seems to have problems with continual or repeated Arduino upload. I also plan to test the upload and communication with a Linux operating system.
Back to work! Today I built the wind baffle and so after the auger is clear back to the experiment.