Performance Update

[jebatty]

Just got the degree days for December and updated my performance record.

2010 – 2011 Heat Performance

Shop: 1536 sq ft; 21,500 cu ft; R19 walls, R39 ceiling, R10 floor, R20 perimeter, R10 to 2.5 ft below grade
Calculated Heat Load (base 60): 40,000 BTUH at -30F outdoor, 60F indoor

Degree Days Normal (base 60) / Degree Days Actual (base 60) / Wood 6050 btu/lb

2010 /    Degree Days Normal    Degree Days     Lbs Wood     Lbs/DDA    BTUH 
2011        1970-2010 .............. Actual (DDA) ... Burned ................ Load


November        1076 ................ 873 ............... 1288 ..... 0.68 ..... 10,823
December        1559 ................ 1470 .............. 1855 ..... 1.26 ..... 15,084
January         1747
February        1375
March           1143

Floor sensor: constant 61F (1F differential)
Outdoor/Indoor air temperature:
+ 20F / + 58F
– 10F / + 55F
– 24F / + 50F

 

[Nofossil]

Nice data. I tried putting it inside a pair of

 tags to get it to line up better - helps a bit. For tables, if you can do it with monospaced font, then paste it into a post and put it in a [code] block it will work better.

 

[huffdawg]

Just got the degree days for December and updated my performance record.

2010 – 2011 Heat Performance

Shop: 1536 sq ft; 21,500 cu ft; R19 walls, R39 ceiling, R10 floor, R20 perimeter, R10 to 2.5 ft below grade
Calculated Heat Load (base 60): 40,000 BTUH at -30F outdoor, 60F indoor

Degree Days Normal (base 60) / Degree Days Actual (base 60) / Wood 6050 btu/lb

2010 /    Degree Days Normal    Degree Days     Lbs Wood     Lbs/DDA    BTUH 
2011        1970-2010 .............. Actual (DDA) ... Burned ................ Load


November        1076 ................ 873 ............... 1288 ..... 0.68 ..... 10,823
December        1559 ................ 1470 .............. 1855 ..... 1.26 ..... 15,084
January         1747
February        1375






March           1143

Floor sensor: constant 61F (1F differential)
Outdoor/Indoor air temperature:
+ 20F / + 58F
– 10F / + 55F
– 24F / + 50F

Hi Jebatty , Im a little slow . Can you explain Degree Days Normal and how you get the#'s for Nov. and Dec. and the Degree Days Actual

Thanx Huff

 

[jebatty]

I got Degree Days Actual from Weather Depot. This is monthly data and available a few days after the end of the month. I see there is a box for Canada, so you may be able to get the data for your location. There is a nearby reporting station in a similar environment to mine close to where I live, so I consider that pretty accurate for my actual location. Be sure to plug in your desired base temperature.

Degree Days Normal I got from (broken link removed). This is base 65 data, so I needed to do a little math to adjust to base 60. I suspect you have a similar data set available from a govt agency for your area in Canada.

Base 60 DD = Base65DD x 60 / 65.

You can calculate your exact location degree days if you have available temperature data or log the data yourself. The simplest way, but not extremely accurate, is to subtract the lo from the hi for the day, and then subtract that from you base temp. That will be your degree days for that day. Do the same for each day of the month and add up the numbers. Or if you have hourly or other more frequent temp readings available, average all of those, and subtract that average from the base temp. That would be more accurate. I doubt over a long period of time that the less accurate method would produce a result much different than the more accurate method.

 

[jebatty]

Apologize for the repeat. Nofo gave me some guidance as to how to better format a table, and here is my effort:

Calculated Heat Load (base 60): 40,000 BTUH at -30F outdoor, 60F indoor

Degree Days Normal (base 60) / Degree Days Actual (base 60) / Wood 6050 btu/lb

2010 /  Degree Days Normal   Degree Days   Lbs Wood   Lbs/DDA    BTUH
2011     1970-2010           Actual (DDA)  Burned                Load

November     1076                  873         1288    0.68     10,823
December     1559                 1470         1855    1.26     15,084
January      1747
February     1375
March        1143

Floor sensor: constant 61F (1F differential)
Outdoor/Indoor air temperature:
  + 20F / + 58F
  – 10F / + 55F
  – 24F / + 50F

 

[Sawyer]

Thanks for the information Jim.

How are you weighing your wood? I will have to weigh my wood and chart the gain. At present I have a clipboard with data sheets. Lots of pencil work but I am curious where my wood is going.

Are you considering moisture content? I do not see any mention of it on this post.

 

[huffdawg]

I got Degree Days Actual from Weather Depot. This is monthly data and available a few days after the end of the month. I see there is a box for Canada, so you may be able to get the data for your location. There is a nearby reporting station in a similar environment to mine close to where I live, so I consider that pretty accurate for my actual location. Be sure to plug in your desired base temperature.

Degree Days Normal I got from (broken link removed). This is base 65 data, so I needed to do a little math to adjust to base 60. I suspect you have a similar data set available from a govt agency for your area in Canada.

Base 60 DD = Base65DD x 60 / 65.

You can calculate your exact location degree days if you have available temperature data or log the data yourself. The simplest way, but not extremely accurate, is to subtract the lo from the hi for the day, and then subtract that from you base temp. That will be your degree days for that day. Do the same for each day of the month and add up the numbers. Or if you have hourly or other more frequent temp readings available, average all of those, and subtract that average from the base temp. That would be more accurate. I doubt over a long period of time that the less accurate method would produce a result much different than the more accurate method.

Thanx for educating me Jim . There is a lot of good stuff to get learned on , on this site.

 

[jebatty]

How are you weighing your wood?
Are you considering moisture content?

If you search "digital postal scale" on *bay, you will find quite a variety of scales at very reasonable prices. I got a 50 lb scale, larger ones are available, but these scales have small platforms and it is difficult to load too much on them. I made a simple U rack (flat bottom) out of scrap lumber to sit on the scale and in which I stack the splits. Most of my burns are 150 lbs or less, so three loads of wood into the rack. Simple, cheap, and while I won't do this forever, for a test period it works very well to get data for future planning. Besides, I'm still burning not more often than every other day, so it is a minor inconvenience.

As to moisture content, I'm assuming 20%, and wood btu content at 6050/lb also is based on 20% and 400F stack temp. My stack temp runs 380-450F, so I'm right in the ball park for that. All of my wood is pine slab wood and/or aspen, two years seasoned, stored outside but covered. It likely has MC in the 10-15% range and therefore somewhat higher btu availability. My finish lumber quality surface moisture meter reads just about 10%. Close is good enough for purposes of planning and evaluating performance.

 

[Sawyer]

Thanks Jim,

I have to get a scale. I would not want to do it forever but I would like to know the true efficiency I am getting. Your guesstimate is similar to my findings on lumber dried in our area. I hate to think of all the slab wood I torched just to get rid of it, not anymore!

 

[sdrobertson]

For a scale, it might be easier to use a common bath room scale and adjust it for your weight. You could weigh a full arm load instead of each piece.

 

[Sawyer]

For a scale, it might be easier to use a common bath room scale and adjust it for your weight. You could weigh a full arm load instead of each piece.

Good idea, I can start the program on tomorrows burn.

 

[jebatty]

I started with a bath scale. But couldn't read it with an armful of wood, and just about the same when I piled wood on the scale. The scale I bought has a "hold" button, so you load it with wood, push the hold button, unload the wood, and then read the scale. Was much easier than the bath scale route. But then again my bath scale probably is 40 years old, and maybe the new digital ones have some better features. Either way you weigh it, you're way ahead.

 

[Sawyer]

Jim, I have started weighing my wood. I am glad you posted your suggestions.

Tonight, if I figured right which I think I did, I found results similar to you. 2 ½ hour burn on 148# hard maple, 150-203 degrees with a 63,000BTU/hr load. Based on Garn 2000 @ 14,600btu/degree gain, 931,300btu total gain or 6293btu/# of wood.

 

[jebatty]

Good to hear this is helpful. It will be interesting to see if other trying the weighing approach and what their results are.

 

[jebatty]

Now added January to the performance data. Also updated is the outdoor / indoor temperature data. I now believe the outdoor temperature sensor, due to its close location to the exterior of the building, may be reading 3 to 6 degrees higher than actual outdoor temperature. This summer I'm going to move that sensor away from the building and in free exposure to the air so it will not be affected by the building or other heat/cold retention structures.

It's good to see that the winter should be well over the cold hump.

Calculated Heat Load (base 60): 40,000 BTUH at -30F outdoor, 60F indoor

Degree Days Normal (base 60) / Degree Days Actual (base 60) / Wood 6050 btu/lb

2010 /  Degree Days Normal   Degree Days   Lbs Wood   Lbs/DDA    BTUH
2011     1970-2010           Actual (DDA)  Burned                Load

November     1076                  873         1288    0.68     10,823
December     1559                 1470         1855    1.26     15,084
January      1747                 1676         2187    1.30     17,784
February     1375
March        1143

Floor sensor: constant 61F (1F differential)
Outdoor/Indoor air temperature:
  + 20F / + 58F
  + 10F / + 57F
     0F / + 57F
  – 10F / + 55F
  - 20F / + 50F
  - 25F / + 50F
  – 30F / + 47F

 

[jebatty]

Now added February to the performance data. The only reason I can think of for the BTUH load to be up relative to December is that colder ground, possibly frost, is penetrating below the slab. I have the perimeter insulated with 2" foam down 30", and 2" foam under the entire slab. Still, my load is much less than I calculated, which is good news. Total wood burned from November - February is 3 cords of pine/aspen mix.

Finally, day highs are now into the 20'sF, nights bouncing around, 0-20F.

Calculated Heat Load (base 60): 40,000 BTUH at -30F outdoor, 60F indoor

Degree Days Normal (base 60) / Degree Days Actual (base 60) / Wood 6050 btu/lb

2010 /  Degree Days Normal   Degree Days   Lbs Wood   Lbs/DDA    BTUH
2011     1970-2010           Actual (DDA)  Burned                Load

November     1076                  873         1288    0.68     10,823
December     1559                 1470         1855    1.26     15,084
January      1747                 1676         2187    1.30     17,784
February     1375                 1282         1762    1.37     15,863
March        1143

Floor sensor: constant 61F (1F differential)
Outdoor/Indoor air temperature:
  + 20F / + 58F
  + 10F / + 57F
     0F / + 57F
  – 10F / + 55F
  - 20F / + 50F
  - 25F / + 50F
  – 30F / + 47F

 

[jebatty]

Here is the March update, and the heating season is nearing an end. Again, the only reason I can think of for the BTUH load and Lbs/DDA to be up relative to prior months is that colder ground, possibly frost, penetrated below the slab. Total wood burned from November - March is 3.75 cords of pine/aspen mix. Looks like 4.5 cords will be a good estimate of need for future years, to allow for some October and April heating.

Calculated Heat Load (base 60): 40,000 BTUH at -30F outdoor, 60F indoor

Degree Days Normal (base 60) / Degree Days Actual (base 60) / Wood 6050 btu/lb

2010 /  Degree Days Normal   Degree Days   Lbs Wood   Lbs/DDA    BTUH
2011     1970-2010           Actual (DDA)  Burned                Load

November     1076                  873         1288    0.68     10,823
December     1559                 1470         1855    1.26     15,084
January      1747                 1676         2187    1.30     17,784
February     1375                 1282         1762    1.37     15,863
March        1143                 1091         1469    1.35     11,945

Floor sensor: constant 61F (1F differential)
Outdoor/Indoor air temperature:
  + 20F / + 58F
  + 10F / + 57F
     0F / + 57F
  – 10F / + 55F
  - 20F / + 50F
  - 25F / + 50F
  – 30F / + 47F