All components of the solar energy system having valves capable of isolating heat generating or heat transfer components shall be provided with an approved, adequately sized pressure relief valve. The installation of the relief valve discharge shall be in accordance with s. SPS 382.40 (5)
The pressure relief valve shall be set at a pressure not to exceed the design pressure of the solar energy system or component or 150 psig, whichever is lesser. The relief valve settings may not exceed the recommendations of the valve manufacturer.
Temperature relief valves shall be of adequate relief rating expressed in Btu/hr for the components served.
Temperature relief valves shall be installed in thermal storage so that the temperature sensing element is immersed within the top 6 inches of a storage tank that contains liquid. The temperature relief valve shall be set to open at 210° F or less.
(d) Combination pressure-temperature relief valves.
Combination pressure-temperature relief valves shall comply with all the requirements of the separate pressure and temperature relief valves.
(e) Entrapped air.
Except for drainback systems, the solar energy system shall provide means for removing air at the highest point of the system when liquid heat transfer fluids are used.
Except as provided in par. (b)
, wherever potable water is interfaced with toxic heat transfer fluids, a double wall heat exchanger, with positive leak detection vented to the atmosphere, shall be provided. The vent shall be located at the lowest part of the heat exchanger or as approved by the department.
Where air is the heat transfer fluid, a single wall heat exchanger may be used. Where potable water is the heat transfer fluid, direct connection to the potable water system is allowed or a single wall heat exchanger may be used.
Solar energy systems using liquid heat transfer fluids shall have a label attached to the thermal storage indicating the heat transfer fluid's name, freezing point and pH, and the system designer's recommendations for checking and maintaining the heat transfer fluid.
The heat transfer fluid contained in a non-draindown or non-drainback system shall be able to withstand temperatures of at least -35ºF before freezing.
Only heat transfer fluids recommended by the system designer for use in the solar energy system shall be used. Ethylene glycol may not be used for solar energy systems in one- and 2-family dwellings, but may be used in buildings.
The heat transfer fluid shall be capable of withstanding design temperatures without rapid thermal degradation.
The flash point of the heat transfer fluid shall exceed, by 50ºF, the maximum operating temperature of the solar energy system.
Drains and other designated heat transfer fluid discharge or fill points in solar energy systems at which toxic, combustible or high temperature heat transfer fluids may be discharged shall be labeled with a warning describing the identification and hazardous properties of the fluid, instructions concerning the safe handling of the fluid, and emergency first aid procedures.
Controls, dampers and valves shall be marked to identify their function. Any control that serves as an emergency shutdown device shall be so identified by a conspicuous and permanent label.
Automatic control of the heat transfer fluid circulation between the collector and thermal storage or load shall be used to limit operations to conditions when useful energy can be collected.
Fail-safe controls shall be designed so that in the event of a power failure, or a failure of any component in the solar energy system, the temperature or pressure or both developed in the solar energy system, will not damage the component or the building or present a danger to the occupants.
Controls shall be selected and installed so that the solar energy system and auxiliary energy system will operate together and independently.
Space heating and control thermostats shall be installed in accordance with the manufacturer's or system designer's instructions. Space heating thermostats shall be located away from drafts, heat sources and exterior walls. Mercury bulb thermostats shall be leveled to assure satisfactory operation. Thermostats mounted outdoors shall be suitable for outdoor environmental exposure.
Controls shall be installed to prevent component damage from thermal shock.
Controls shall include provisions for manual bypass, adjustment or override of automatic controls as is required to facilitate installation, startup, shutdown and maintenance.
All materials used in the solar energy system shall be compatible. All components in contact with the heat transfer fluid used in the solar energy system shall be compatible with the heat transfer fluid.
All metal parts, including screws, bolts, and washers, which are not inherently corrosion resistant and are exposed to atmospheric conditions, shall be protected from corrosion by painting, plating, or similar means.
Metallic parts which provide protection to either electrical components or internal building structures shall be galvanically compatible and protected from corrosion.
SPS 371.22 History
Cr. Register, June, 1986, No. 366
, eff. 7-1-86; corrections in (3) (a) and (b) made under s. 13.93 (2m) (b) 7., Stats., Register June 2002 No. 558
; correction in (3) (a) 1., (b) made under s. 13.92 (4) (b) 7., Stats., Register December 2011 No. 672
Collector certification requirements.
After January 1, 1987, all collectors shall be certified by the Solar Rating and Certification Corporation (SRCC), the Air Conditioning and Refrigeration Institute (ARI) or equivalent. This provision does not apply to home-built systems, custom-built systems and small manufacturers. As used in this subsection:
"Home-built system" means an owner-installed solar energy system incorporating a collector assembled by the system owner from components, but does not include manufactured collectors supplied as an integral unit and installed by the owner.
"Custom-built system" means a one-of-a-kind solar energy system incorporating a collector fabricated at the installation site from components, but does not include modular systems in which the modular components are assembled at the installation site.
"Small manufacturer" means a business that builds or assembles less than 2500 square feet of collector per year and elects not to list with SRCC or ARI.
SPS 371.23 Note
Certification of collectors by the SRCC and the ARI is based on the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards 93-77 and 95-1981
. Further information can be obtained from the Solar Rating and Certification Corporation, 1001 Connecticut Avenue, N.W., Suite 800, Washington, D.C. 20036, or the Air-Conditioning and Refrigeration Institute, 1501 Wilson Boulevard, 6th Floor, Arlington, VA 22209.
(2) Collector tilt and orientation.
Collectors shall be installed as close to the optimum tilt angle as conditions allow and within 45º of due south.
SPS 371.23(3)(a)(a) Transmission losses due to outgassing.
Outgassing of volatiles from components may not reduce the collector performance below the declared collector performance when the collector is exposed to the temperatures and pressures that will occur in actual service.
(b) Dirt retention.
The cover plate under normal weather conditions may not, with normal maintenance, collect or retain excessive dirt.
Glass used in collector construction shall be tempered.
Glazings subject to human impact and within 7 feet of ground level shall be safety glazing material constructed, treated or combined with other materials so as to minimize the likelihood of cutting and piercing injuries resulting from human impact with the glazing material.
Plastic used in collector construction shall be capable of withstanding the maximum operating pressure and temperature, and shall be used in accordance with manufacturer's recommendations.
The collector shall be capable of withstanding no-flow conditions.
The construction of the collector shall provide protection against:
Internal leakage into the collector from environmental conditions; and
Internal leakage of the heat transfer fluid from the collector from cleaning operations as performed during routine maintenance as specified in the operation and maintenance manual.
All materials used in the absorber or heat transfer fluid conduits may not be pitted, corroded, or otherwise degraded by the heat transfer fluid to an extent that will result in failure during its design life.
In closed loop systems, aluminum may not be connected with copper or iron. Separation of different pipe materials by isolating bushings is not acceptable.
(i) Ultraviolet stability.
All materials used in the collector may not degrade when exposed to ultraviolet radiation to an extent that will reduce the collector performance below the declared collector performance.
Collector insulation shall be capable of withstanding moisture, ultraviolet radiation, and environmental exposure.
2. `Mounting on the ground.'
When collectors are located on concrete slabs, the slab shall be a minimum of 4 inches thick. Collectors shall be located a minimum of 6 inches above the ground surface. Collectors installed on the ground shall be adequately supported and anchored.
3. `Collector stresses.'
Structural supports may not impose undue stresses on the collector.
All wood components used in collector mounting which are exposed to the environment shall be resistant to decay in accordance with s. SPS 371.21 (4) (d)
. Wood used in collector frames or housings shall be protected against structural degradation due to high temperature exposure.
6. `Tilt and orientation.'
Structural supports shall be constructed to maintain collector tilt and orientation within design conditions throughout the life of the solar energy system.
SPS 371.23(4)(b)1.1. `Instructions.'
Collectors shall be installed in accordance with the instructions provided by the system designer.
2. `Fire protection.'
Collectors made of combustible materials may not be located on or adjacent to construction required to be of noncombustible materials. Collector installation shall also comply with s. SPS 371.21 (6)
Safe access to components subject to deterioration or failure, such as rubber hoses, joint sealants, and cover plates, shall be provided to allow for maintenance or repair. For roof-mounted collectors, the work space adjacent to collectors and provisions for safe placement of ladders shall be considered.
4. `Moisture protection.'
Collector installation may not contribute to moisture buildup, rotting, or other accelerated deterioration of roofing materials. Collectors and structural supports shall be installed in a manner such that water flowing off the collector surface and structural supports will not accelerate formation of ice dams or cause water damage to the building or dwelling. Provisions shall be taken to minimize buildup of snow upon collectors, which may reduce their effectiveness.
5. `Caulking and sealing.'
Joints between structural supports and buildings or dwellings shall be caulked and flashed to prevent water leakage. Bolts or other means of fastening the collector or structural supports to the roof shall be sealed from water penetration.
6. `Filling and draining.'
Interconnecting piping or ducting shall be installed to minimize flow restrictions and to provide balanced flow. Piping shall be installed to allow for filling and draining.
SPS 371.23 History
Cr. Register, June, 1986, No. 366
, eff. 7-1-86; correction in (4) (a) 1., 4., 5., (b) 2. made under s. 13.92 (4) (b) 7.
, Stats., Register December 2011 No. 672
This section shall apply to active solar energy systems and components that use air as a heat transfer fluid.
SPS 371.24(1)(a)(a) Size.
Air distribution components shall be adequately sized to insure a uniform distribution of air.
SPS 371.24(1)(b)1.1. `Flow efficiency and health hazard.'
Duct and fan systems shall be protected against accumulation of deposits of dust or dirt that could reduce flow and efficiency or create a potential health hazard when admitted into occupied spaces.
2. `Air filters'.
Air filters shall be installed on the outlet side of the thermal storage in solar energy systems. Air filters shall be removable to allow cleaning. Solar energy systems used for space heating shall incorporate the use of a high efficiency air filter installed in the cold air riser duct to the collectors unless the air does not pass over the absorber.
2. `Exterior ducts'.
Ducts located outside the dwelling or building shall be constructed of galvanized steel or corrosion-resistant metal.
(e) Temperature, pressure and exposure.
Ducts, insulation, gaskets, sealants and adhesives shall be capable of withstanding maximum operating temperatures, pressures and environmental exposure.
Solar energy systems providing both space heating and domestic water heating shall be equipped with a bypass of the thermal storage during the nonheating season.
SPS 371.24(2)(a)(a) Duct system.
The primary solar duct system shall be sealed in accordance with the following requirements:
All joints in metal ducts shall be made with good fit-up and closure.
Joints and seams shall be sealed with adhesives, mastics or compatible combinations of tape binders and adhesives in ducts conveying air to and from storage units and solar collectors and in ducts conveying air from such circuits to points of connections with ducts circulating air to and from the occupied space.