Minor changes in the software that force the boiler to maintain a tighter range from the set point has cut the fuel consumption from 3 (40 pound) bags of pellets to 2 daily. These software improvements and a extension to the pellet hopper mean the boiler will now run 24 hours without needing additional fuel. The hopper extension adds at least another 40 lb bag of pellets capacity bringing the total capacity to approx. 2 1/2-3 bags. I haven’t measured only estimated.
The boiler set point is currently set at 135°F which seems to work just fine for the temperatures we have been having and the software is consistently running within4 degrees of set point. This range may seem excessive but seems to run just fine. The program is becoming more modular in that there is only one number to change, the set point. The set point currently is a variable declared in the setup section of the program but eventually the set point will be self adjusted by the program based on the outside temperature. Economy and efficiency by software optimization is the goal for this next week.
We have had a very mild winter in my opinion. The Heating Degree Day total for the month of Dec 2011 was 1091 as measured by the local weather station. The normal is 1209 HDD a difference of 118 HDD, not as much as I would have thought. The total for the month of January 2012 so far is 1140 with four days to go, with a normal of 1419. We’ll see how the month ends but if it continues as the average day it will be short approx the same number of HDD as last month,December. My interest in HDD is to see if there is a correlation to HDD and fuel consumption. There should be and if there is than the fuel economy is starting to improve. As I told a friend of mine, at this point the boiler is like a truck I used to own, 10 mpg going uphill loaded, 10 mpg empty going downhill….so seeing fuel consumption changing to track the weather will be the first step to seeing some optimization.
Software work on fuel economy and the extrapolation of costs for the upcoming remainder of the season is of great interest. The next step in fuel economy may be better insulation of the boiler and piping and will not be as simple as software improvements. But if I can get a correlation between the outside temperature and fuel consumption that is measurable then the software will be nearly optimized and further improvements will have to come from physical changes. This week sees a 40 pound bag and $4.00 improvement per day, $28/week, $112 per month. Next week’s goal: another $60/month. I am hoping for a total seasonal heating cost of $500 or less using $200/ton pellets. I will consider that a huge victory for heating a 2300 sq ft house with 3 garage doors.