HDD’s vs. Pellets Part 3

The HDD’s reported from Weather Underground was 324 for the week of December 8-14 and I used 24 bags of fuel, more than would have been calculated by a simple ratio based on last weeks fuel usage, however very close to the trend line of the original scatter plot which I will post again here.  So as time goes on the prediction gets a bit better.  HDD vs. Pellets 2nd week December

It’s shaping up to be about 13.5 HDD’s per bag of pellets, I have made minor changes to the software so, I think these numbers are getting more stable as time goes on. Note that December 2012 for the first two weeks added up to 431 HDD compared to December 2013’s first two weeks 548 HDD.

HDD Update for the first week of December

In the first week of December I have used 15 bags of pellets to heat the house and shop including hot water. This weeks heating and hot water costs were $64.50.  In the last post I calculated a monthly usage of 68 bags if this month followed the trend for December 2012 Heating Degree Days (HDD).  So with 22.6% of the month gone I have used 22.0% of the fuel predicted.  Probably not a good sign considering it will get colder as the month goes on (probably).  In the first week the HDD were 224 in Springfield, VT.  Last year the first week of December there were 211 HDD and not until the 3rd week was the weekly total as high as 224 barely topping this years first week at a whopping 226.  So this may indicate a colder month than last year’s December.

No further progress on the boiler rebuild, I got distracted by obtaining a “free” hot tub.  It had a fried control board, as well as a fried pump motor.  I am sure the two are related and this should give me a clue as to how to fix the control board but, I have decided to replace the control board with a home built board consisting of relays.  Several of these relays will be controlled by switches by the operator, and several will be controlled by an Arduino  for example controlling the circulator pump and heater as well as reading the temperature sensors and reading the operators desire to raise or lower the temperature.  That will probably keep me occupied in my spare time for a week or so.  The second project in the shop is a sander which is giving me problems.  I ended up buying a second sander to make sure I would be able to meet my contractual obligations but in the meantime, there is a sander taking up a lot of space while I wait for parts.  It is a treat to work on it inside however, so I am not complaining just rationalizing why I am not working on the new boiler feed for chips.

HDD vs. Fuel Used

HDD vs. Pellets

Above is a scatter plot of Heating Degree Days (HDD) taken from Weather Underground data from the weather station in Springfield VT. Not exactly Newport, NH but close enough for this graph. It’s important to note that the beginning of October was quite nice which resulted in a fair number of days of timed burns, starting the boiler at 4 pm and running it until 9 pm for example. It quickly became obvious with Novembers below average weather that this would not result in satisfactory comfort and the boiler has been running continuously for most of the month. The trend-line looks like you would expect to see it, but the scatter data is quite varied. It will be interesting to see if this data correlates better as the winter continues.

The total pounds of fuel burned Heating season to date: 92 bags @40 pounds/bag= 3680 pounds vs. a total HDD to Date of 1444.    Last year’s data for December indicates a HDD total for the month of 1069.  This should result in 68 bags burned for the month for a total of 2720 pounds.  Using $215 per ton this should be a monthly cost of $292.40 This is both heat and hot water.  Be interesting to see at the end of the month how close the prediction comes.

You may remember I added a function to collect HDD data at one point, however it never seemed to work as well as it should have so I stopped using it,  I am now considering reviving a variation of that function using an array for the max and min hourly numbers to get a more accurate HDD local number.  I’ll post the code when I finish.