Welcome to the SunEarth Newsletter–bringing you the best in solar thermal, industry news, and the latest SunEarth updates each month.
TAKE THESE STEPS TO DETERMINE SIZING
Whether your system is designed for hydronic heating, cooling, geothermal, or solar thermal, an expansion tank plays an important part in maintaining system operation.
Expansion tanks used for direct water heating systems are not the same as those used for indirect glycol based non-potable fluids. Direct water expansion tanks are designed to resist corrosion that may occur due to oxygen in the water. Indirect expansion tanks have bladders designed to resist chemicals typically found in glycol based non-potable fluid applications.
For indirect solar systems, the expansion tank must be acceptable for use with propylene glycol or other heat transfer fluid used in the collector loop. In addition, the temperatures and pressures in indirect solar systems can be significantly higher than found in typical hydronic systems. Care must be taken that the expansion tank selected will meet the requirements of the solar application.
One important difference is thatf for a steam back indirect/glycol system a design must account for phase change within the collectors when sizing. For a direct system, there is no phase change within the collectors to take into account when sizing for fluid expansion.
It is imperative that the expansion tank be sized and charged properly for the specific system being installed. Incorrect sizing and charging of the expansion tank can lead to problems that could cause the system to function improperly or even fail. The method for sizing the expansion tank is detailed below.
Size expansion tank for system with 3 x EP-40 collectors; 16 ft. of 3/4” Type L copper pipe above collectors on the roof; total pipe run for the system is 80 ft. of 3/4” Type L copper pipe; and the heat exchanger volume is 2.2 gallons. The expansion tank is pre-charge is 28 psi and the PRV is set at 100 psi.
Collector capacity = 3 * 1.2 = 3.6 gallons
Pipe on roof capacity = 2.5 * 16/100 = 0.4 gallons
Steam volume in stagnation = 3.6 + 0.4 = 4.0 gallons
Total volume of system piping = 2.5 * 80/100 = 2.0 gallons
Collector capacity = 3 * 1.2 = 3.6 gallons
Heat exchanger capacity = 2.2 gallons
Total fluid volume = 2.0 + 3.6 + 2.2 = 7.8 gallons
Allowance for fluid expansion = 7.8 * 0.05 = 0.39 gallons
Minimum required acceptance volume of tank = 4.0 + 0.39 = 4.4 gallons
System minimum absolute pressure Pmin = 28 +14.7 = 42.7 pisa
System minimum absolute pressure Pmax = 100 + 14.7 = 114.7 pisa
Minimum required tank capacity = 4.4 / (1 – (42.7 / 114.7) ) = 7.0 gallons
PROJECT SPOTLIGHT: PLACENTIA VETERANS VILLAGE
Project Name: Placentia Veterans Village
Location: Placentia, California
Installed: January 2020
Installed by: California Solar Integrators, Inc. dba Cal Solar
A SAFE HAVEN FOR LOW-INCOME ORANGE COUNTY VETERANS.
The City of Placentia partnered with the County of Orange, Mercy Housing California, and New Directions to plan, design, construct and administer the Placentia Veterans Village, a permanent supportive housing development that serves military veterans who are homeless or disabled.
California is home to nearly 2 million veterans. Approximately 137,000 veterans live in Orange County. There is an estimated 3,500 homeless veterans in Orange County and over 6,000 Orange County veterans are unemployed at any given time.
The development site is a 3.65-acre unimproved site comprised of two parcels, one is owned by the Orange County Flood Control District and the adjacent parcel is owned by a private party. The Development is located adjacent to a newly constructed street located near the intersection of Orangethorpe Avenue and Lakeview Avenue; north of the Atwood Flood Control Channel. The current property is vacant and has frequently been used for illegal dumping. The new Development will improve the property significantly while addressing a need in Orange County and throughout the nation.
The Development includes 50 furnished apartment homes (49 for veterans and 1 for one-site management unit), a courtyard, community garden, recreation room, energy efficient design and appliances, computer room, and resident services offices. The state-of-the-art development is LEED Gold, utilizing energy efficient design principles and building materials.
Funding for the project came from a variety of sources, including a federal Low Income Housing Tax Credit, California Proposition 41, a conventional mortgage (relying on a HUD VASH subsidy), Project Based HUD VASH and/or Project Based Section 8 – Orange County Housing Authority, and a pending City of Placentia Development Impact Fee Deferral.
Location: 1925 Veterans Way, Placentia, California 92870
Application: Domestic Hot Water
Rated Power Output: 327.2ft^2 / 10.76 * 0.7 = 21.29 kW
Yearly Energy Output (kWh): 21.29*5.13*.44*365 = 17,540.36 kwh
Solar Collectors: (8) 4' x 10' SunEarth Thermoray (TRB-40) Flat Plate Collectors
System Format: Closed Loop Drainback
Pump Station: Solar Station XL
WEBINAR: Solar Thermal Applications (Commercial) PART 2
September 17, 2020: 11:00 AM (PST)
In part two of this two part webinar, we continue the discussion to find out how commercial and industrial applications benefit from this tried and true technology. A deep dive into how medium and large scale solar thermal water heating systems are sized, designed, and deployed.
SEIA SHC Symposium
September 24, 2020: 9:30 AM - 12:30 PM (PST)
Save the Date for the 2020 virtual SHC Symposium!