ASHRAE Journal - September 2009 - 50

collection periods. This caused erroneous Btu collection data and short cycled the pump as the controls program was trying to prevent a supposed reradiation problem. We commanded the pump to run continuously during the daily collection period until we could get back to the project to determine the source of the problem. The solar radiation sensor data energy potential showed that we were not collecting the daily energy we had obtained previously. The glycol pressure sensor, which had also been wired just weeks previously, showed that we had lost glycol from over the winter. Returning to the project, we tightened unions where we noticed glycol drips, cleaned the strainer, which improved the pump flow, and replaced a faulty temperature sensor on the collector inlet, which explained the diminished Btu collection. We also recharged the glycol to make up the loss from over the winter. In early May 2009 the glycol boiled due to a pump vapor lock because the solar radiation was higher than it had been in the winter. We suspected a problem with the glycol expansion tank, which was installed without access to the pressure port. We had to remove the tank from the line for testing where we measured 50 psi (345 kPa), much higher than the 12 psi (83 kPa) listed on the label. We bled the pressure back to 12 psi (83 kPa), reinstalled the tank, and charged the glycol and it has been operating normally since. Because the automation system monitors all of the sensors, our live system data Web site (www.utahashraesolar.tzo.com) has become popular for those in the solar industry wanting to monitor solar performance. It is also used as an instructional tool for schools and solar energy classes. We have learned a lot about how solar hot-water systems operate, especially in the cold Utah climate, and are anticipating the performance this summer. Lessons Learned This past winter, Salt Lake City experienced inversions and cloudy days that diminished our solar collection. • The winter city water temperatures have dropped to the low 40s and the summer city water has been almost 60°F (16°C). • The collector angles are at our latitude of 40°, which means peak collection should be in March and September. • We are anticipating the comparison of the owner’s summer gas bills from summer 2008 to summer 2009 to compare with the estimated savings from our logging of the solar-collected Btus. • The live data reported by the automation has allowed us to remotely diagnose many of the operational problems that we encountered. The energy calculations allowed us to enhance the solar system performance. From following the live data Web site, we suspect that the discrepancy between the accumulative solar-collected Btus and the cumulative DHW usage Btus is the result of the heat gain from the boiler room to the domestic water/tank piping system. System Recommendations • We found that with the daily average usage remaining similar, we can collect and store solar heated water that is about 70°F (39°C) over ambient. In the summer our daytime temperatures average 80°F to 90°F (27°C to 32°C), and we were achieving 150°F (66°C) regularly. In the winter with 30°F to 40°F (–1°C to 4°C) in the daytime, we were storing 100°F to 120°F (38°C to 49°C) regularly. • Reduce the load with low usage fixtures and determine the daily load profile. • Size the system for a reasonable payback, not the entire load. • Design the system for the climatic conditions and evaluate the structure for collector location and angle, wind loading, and pipe routing. Ensure adequate room to prevent snow buildup and allow natural snow removal. • If the system is being added to an existing building, carefully survey the piping, connection points, and valving to ensure a simple interface. Just because the hot-water heating system has been operational for several years, don’t assume all of the components are working. • Verify proper operation of existing water heaters, mixing valves, circulation pumps, check valves and other key components, as the solar heated water can be much hotter than a conventional DHW system. You can’t just turn off the sun when it’s convenient. • Since the solar collection capacity will likely exceed usage at times during the year, the design must include a means of rejecting the excess heat along with ensuring pump operation during power outages to prevent system boil-overs (PV pumping or emergency power). Installation Recommendations • The plumbing contractor should be the prime contractor and be responsible to coordinate the roofing, electrical, insulation, and controls. • The piping schematic should be detailed, showing correct locations for www.info.hotims.com/25208-59 50 ASHRAE Journal September 2009

ASHRAE Journal - September 2009

Table of Contents for the Digital Edition of ASHRAE Journal - September 2009

ASHRAE Journal - September 2009
Contents
Commentary
Industry News
Letters
Meetings and Shows
Getting to Net Zero
Feature Articles
How High Can You Go? Building Height and Net Zero
Lab for Learning
Solar Hot-Water Heating System: Lessons Learned
50th Anniversary—Low Pressure Steam Heating Systems
Building Sciences
Products
Emerging Technologies
People
Classified Advertising
Advertisers Index
ASHRAE Journal - September 2009 - ASHRAE Journal - September 2009
ASHRAE Journal - September 2009 - Cover2
ASHRAE Journal - September 2009 - 1
ASHRAE Journal - September 2009 - 2
ASHRAE Journal - September 2009 - Contents
ASHRAE Journal - September 2009 - 4
ASHRAE Journal - September 2009 - Commentary
ASHRAE Journal - September 2009 - Industry News
ASHRAE Journal - September 2009 - 7
ASHRAE Journal - September 2009 - 8
ASHRAE Journal - September 2009 - 9
ASHRAE Journal - September 2009 - Letters
ASHRAE Journal - September 2009 - 11
ASHRAE Journal - September 2009 - 12
ASHRAE Journal - September 2009 - 13
ASHRAE Journal - September 2009 - 14
ASHRAE Journal - September 2009 - 15
ASHRAE Journal - September 2009 - Meetings and Shows
ASHRAE Journal - September 2009 - 17
ASHRAE Journal - September 2009 - Feature Articles
ASHRAE Journal - September 2009 - 19
ASHRAE Journal - September 2009 - 20
ASHRAE Journal - September 2009 - 21
ASHRAE Journal - September 2009 - 22
ASHRAE Journal - September 2009 - 23
ASHRAE Journal - September 2009 - 24
ASHRAE Journal - September 2009 - 25
ASHRAE Journal - September 2009 - How High Can You Go? Building Height and Net Zero
ASHRAE Journal - September 2009 - 27
ASHRAE Journal - September 2009 - 28
ASHRAE Journal - September 2009 - 29
ASHRAE Journal - September 2009 - 30
ASHRAE Journal - September 2009 - 31
ASHRAE Journal - September 2009 - 32
ASHRAE Journal - September 2009 - 32a
ASHRAE Journal - September 2009 - 32b
ASHRAE Journal - September 2009 - 33
ASHRAE Journal - September 2009 - 34
ASHRAE Journal - September 2009 - 35
ASHRAE Journal - September 2009 - 36
ASHRAE Journal - September 2009 - 37
ASHRAE Journal - September 2009 - Lab for Learning
ASHRAE Journal - September 2009 - 39
ASHRAE Journal - September 2009 - 40
ASHRAE Journal - September 2009 - 41
ASHRAE Journal - September 2009 - 42
ASHRAE Journal - September 2009 - 43
ASHRAE Journal - September 2009 - Solar Hot-Water Heating System: Lessons Learned
ASHRAE Journal - September 2009 - 45
ASHRAE Journal - September 2009 - 46
ASHRAE Journal - September 2009 - 47
ASHRAE Journal - September 2009 - 48
ASHRAE Journal - September 2009 - 49
ASHRAE Journal - September 2009 - 50
ASHRAE Journal - September 2009 - 51
ASHRAE Journal - September 2009 - 52
ASHRAE Journal - September 2009 - 53
ASHRAE Journal - September 2009 - 50th Anniversary—Low Pressure Steam Heating Systems
ASHRAE Journal - September 2009 - 55
ASHRAE Journal - September 2009 - 56
ASHRAE Journal - September 2009 - 57
ASHRAE Journal - September 2009 - 58
ASHRAE Journal - September 2009 - 59
ASHRAE Journal - September 2009 - 60
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ASHRAE Journal - September 2009 - 69
ASHRAE Journal - September 2009 - 70
ASHRAE Journal - September 2009 - 71
ASHRAE Journal - September 2009 - Building Sciences
ASHRAE Journal - September 2009 - 73
ASHRAE Journal - September 2009 - 74
ASHRAE Journal - September 2009 - 75
ASHRAE Journal - September 2009 - 76
ASHRAE Journal - September 2009 - 77
ASHRAE Journal - September 2009 - 78
ASHRAE Journal - September 2009 - 79
ASHRAE Journal - September 2009 - 80
ASHRAE Journal - September 2009 - 81
ASHRAE Journal - September 2009 - Products
ASHRAE Journal - September 2009 - 83
ASHRAE Journal - September 2009 - Emerging Technologies
ASHRAE Journal - September 2009 - 85
ASHRAE Journal - September 2009 - 86
ASHRAE Journal - September 2009 - 87
ASHRAE Journal - September 2009 - 88
ASHRAE Journal - September 2009 - 89
ASHRAE Journal - September 2009 - People
ASHRAE Journal - September 2009 - 91
ASHRAE Journal - September 2009 - 92
ASHRAE Journal - September 2009 - Classified Advertising
ASHRAE Journal - September 2009 - 94
ASHRAE Journal - September 2009 - 95
ASHRAE Journal - September 2009 - Advertisers Index
ASHRAE Journal - September 2009 - Cover3
ASHRAE Journal - September 2009 - Cover4
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