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.
After having the issues described in the last post the decision was made to reconfigure the feed for the third time. Hopefully the third time is the charm. The feed is now horizontal again with a reconfigured air box and single fan blowing along with the exhaust fan. The auger was extended into the burn area to allow the pipe to be mounted flush to the inner surface of the mounting plate and so that the auger will push the burning pile down the burner trough. After some minor glitches the burner is up and running. I made some minor changes to the software to allow the burner to run more at a lower temperature and changed the setpoint to 140°F from 135°F. Minor changes but all part of the tweaking and learning process.
The goal for this coming week will be to monitor the fuel usage and see if the system can keep up with the predicted below zero temperatures forecast for tonight.
The New Year practically demands resolutions and change for the better. So with that constant improvement theme in mind I am publicly stating my goal to lose 15#’s and so I am starting from 195.7. My second resolution is the constant improvement of the boiler. So here we go……
Auger feeding failure due to the motor stalling demanded the sprocket change on the auger motor feed assembly. The sprocket I chose doubles the torque available for feeding pellets. Since the shaded pole motor is constant speed the program had to change to double the auger run time. So taking the data I had gathered I changed the program in two ways.
I changed the times to accommodate the speed change demanded by the sprocket change and I changed the paradigm to have constant run time and vary the dwell or off time. The increased torque is a vast improvement and since the change it has had no problem feeding even adding an entire bag of pellets at one time.
A second advantage of the change is the improvement of the LCD display. I think that this problem is now fixed since the LCD has been running without garbling the characters for several hours, long past the time when the LCD would normally have failed. By increasing the torque the auger feed motor is running at less amp draw and so it feeds back less to the relays. I also grounded the relay in a more positive way.
I’m a big proponent of having some skin in the game. If you don’t you are fooling yourself. I learned that in the financial markets. If you can trade on paper you have a better chance of succeeding in the real world trading but when you have real money involved sometimes you can’t make the decisions needed.
That seems to be the case with the LCD display. After having worked out some basic electrical issues the display worked fine for 3-4 days with the relays tripping but no motors hooked up. Now that the motors are hooked up again it seems to be garbling the LCD. So, the only assumption I can make is there is some kind of electro-magnetic field or a bad ground that is interfering with the LCD. The motor is a shaded pole motor which has a large electromagnetic core which no doubt radiates interference for the controller. Below is a picture of a similar motor.As a fix I think I will twist the LCD wires so they are less of an antenna and see if using some tin foil to shield inside the project box as well as above the feed motor and see if I can improve the ground.
Limited success, the temperature in the tank did rise quickly and peaked at approx. 90°F before I shut the boiler feed off. The water in the boiler started at 56°F. The boiler smoked excessively and I think the top exhaust fan needs to be more robust. At present the bottom draft feed fans are approx. 1/3 more cfm than the top fan. To induce some negative pressure and reduce the smoking issues the top fan needs to increase. The other issue is the auger feed. The motor had a few issues with binding, The motor may have to be more powerful as well. I will take apart the feed tomorrow and hopefully determine where it was binding up. With luck there was a misaligned bearing or some other explanation. Otherwise I am a little at a loss. Over the weekend the piping got run with help. I mounted the 3/4″ copper on Unistrut this connected to the oil fired hot water boiler. A nice neat job if I say so myself. The 4″ .125 wall tube I used for an exhaust pipe seemed to work fine and stay cool in the 1/2 hour I ran the boiler. I still had some issues with the LCD screen however I am now convinced that this problem will fix it self with a separate power supply for the relays.
I wrote a very simple program this morning for the boiler control. No frills at all, and there were minor LCD issues. I think the LCD is very susceptible to voltage fluctuations. I will test this theory tomorrow as well.
The chain arrived from McMaster-Carr last night so today a friend and I hooked up the drive motor for the auger and we did a timing test. The assumption is the pellets will yeild approx. 5000 BTU’s per pound. So after running the auger for a minute we weighed the sample and with the weight we calculated the feed rate at approx. 30 secs every 2.5 minutes. We will have to adjust the rate as needed for the test. I got a great email from a friend with some useful suggestions for the code which is still having issues. I incorporated all the suggestions and look forward to more useful suggestions.