Readings from the top of our Hot Water Tank

The data presented below is in three main sections:
  1. By period, showing the analysis of the temperature at the top of the tank (T3) during the three measurement periods of Morning, Noon and Afternoon. Specifically, the measurements are taken between 8am and 9am for "Morning", 12pm and 2pm for "Noon" and between 6pm and 8pm for afternoon
  2. By month/year, showing the transition of the solar hot water heating at our home since installation
  3. By the weather conditions in Durham NC, USA, as reported by http://www.weather.com at noon on each day. This section is included to see the impact inclement weather has on the solar hot water heating measurements
Notes: View the full data or graphical plots of the data.

Solar Hot Water Heating days
Month Number of
daily
readings		Number of
readings
<= 125F		% of days
requiring
supplemental
heating		 % of days
where ALL
water heated
just by
Solar Heat		Mean morning
T3 Temp (F)		Standard
Deviation
Overall 437 72 16.48 83.52 145.086 16.036
MAR200729 4 13.79 86.21 140.000 15.639
APR200730 3 10.00 90.00 146.800 13.979
MAY2007 31 5 16.13 83.87 145.839 14.942
JUN200726 1 3.85 96.15 154.458 11.398
JUL200729 0 0.00 100.00 156.714 7.138
AUG200730 0 0.00 100.00 160.621 5.827
SEP200729 1 3.45 96.55 157.481 9.629
OCT2007 28 5 17.86 82.14 148.148 16.379
NOV200730 7 23.33 76.67 135.067 14.244
DEC200720 10 50.00 50.00 125.600 10.684
JAN2008 31 16 51.61 48.39 125.138 10.024
FEB200826 4 15.38 84.62 139.000 11.927
MAR200831 3 9.68 90.32 145.806 12.833
APR200830 12 40.00 60.00 137.733 15.292
MAY200831 1 3.23 96.77 151.923 10.896
JUN2008 6 0 0.00 100.00 159.167 3.251

In the table above the figures in RED are for days where supplemental heating was required to heat our water to the 120 F temperature recommended as by Energy Star Home Saving Tips for heating hot water to. The figures in GREEN are for days where no supplemental heating was required, or stated another way.... when all the hot water in that day was heated ONLY by the radiant heat of the Sun.

The data in green is the GOOD data. When we installed the system we budgeted and assumed that we would typically get 80% of our hot water heated by the sun. The figures above are the ACTUALS, showing both the "overall" figures but also the data on a monthly basis.

The mean T3 temperature is the MORNING temperature, this is the temperature of the hot water in the tank some 16 or so hours after the end of the previous solar day.

Summary of data values
This data is also available graphically.

PeriodPercentile
10th25thMedian75th 90thMin valueMax valueMeanNumber of readings Standard Deviation
Morning (8am to 9am) 122.50 131.00 151.00 159.00 162.00 99.00 166.00 145.09 420 16.0364
Noon (12pm to 2pm) 128.00 142.50 161.00 175.00 177.00 107.00 183.00 156.74 92 19.4184
Afternoon (6pm to 8pm) 130.00 143.00 165.00 172.00 175.00 110.00 180.00 157.26 413 18.1799
MonthPercentile
10th25thMedian75th 90thMin valueMax valueMeanNumber of readings Standard Deviation
MAR2007 120.00 137.00 151.00 165.50 170.00 99.00 179.00 149.55 64 18.9091
APR2007 131.00 149.50 156.50 170.50 174.00 109.00 183.00 155.62 68 16.1190
MAY2007 119.00 140.50 155.00 167.50 175.00 102.00 177.00 152.00 68 18.3417
JUN2007 144.00 156.50 163.00 174.50 176.00 120.00 178.00 161.92 52 12.8274
JUL2007 154.00 159.00 164.00 171.00 175.00 132.00 177.00 163.67 63 8.9081
AUG2007 160.00 161.00 165.00 173.00 176.00 140.00 178.00 166.39 62 7.7594
SEP2007 149.00 159.00 165.00 175.00 177.00 123.00 180.00 164.86 63 12.2222
OCT2007 122.00 139.00 160.00 169.00 174.00 115.00 181.00 154.59 59 18.3689
NOV2007 117.00 130.00 140.00 155.00 167.00 111.00 176.00 141.14 69 16.5051
DEC2007 115.00 118.00 129.00 138.00 143.00 109.00 159.00 129.41 41 12.1243
JAN2008 115.00 118.00 129.00 137.00 149.00 110.00 167.00 129.86 65 13.8991
FEB2008 126.00 133.00 144.00 156.00 166.00 114.00 179.00 145.13 55 15.6608
MAR2008 126.00 139.00 153.00 166.00 172.00 123.00 177.00 151.55 65 15.9844
APR2008 123.00 123.50 146.00 160.00 167.00 123.00 175.00 144.45 60 17.6188
MAY2008 140.00 153.00 159.00 167.00 173.00 123.00 180.00 158.15 61 12.6212
JUN2008 156.50 158.00 163.00 167.00 169.50 155.00 170.00 162.80 10 5.3500
JUL2008 0
AUG2008 0
SEP2008 0
OCT2008 0
NOV2008 0
DEC2008 0
JAN2009 0
FEB2009 0
MAR2009 0
APR2009 0
MAY2009 0
JUN2009 0
Classified by the Mid day
Weather conditions
(per weather.com)
NOTE: Morning readings excluded		Percentile
10th 25thMedian75th90thMin valueMax value MeanNumber of readingsStandard deviation
.. 174.00 174.00 174.00 174.00 174.00 174.00 174.00 174.00 2 0.0000
Cloudy 115.00 123.00 131.00 147.00 172.00 107.00 175.00 137.58 65 18.5783
Fair 140.00 161.00 170.00 174.00 177.00 120.00 183.00 164.99 232 13.5693
Fog 111.00 112.50 115.00 122.50 129.00 111.00 129.00 117.50 4 7.9373
Haze 133.00 133.00 135.00 168.00 168.00 133.00 168.00 145.33 3 19.6554
Light Rain 119.00 123.00 136.00 140.00 154.00 116.00 155.00 134.31 13 12.7304
Light Snow 134.00 134.00 134.00 134.00 134.00 134.00 134.00 134.00 1
Mostly cloudy 125.00 131.00 146.00 163.00 166.00 114.00 175.00 145.93 43 16.9093
Partly cloudy 140.00 149.50 164.00 171.00 175.00 115.00 178.00 159.47 96 13.8905
Rain 110.00 115.50 121.50 124.00 126.00 110.00 126.00 119.75 4 6.8496
Sunny 166.00 169.00 174.00 176.00 177.00 166.00 177.00 172.43 7 3.9521

View the full data.
Email: darrell AT nearto.us
Web: http://www.nearto.us/
Copyright (c) 2007-2009 Darrell Edgley