Results From 20 Years of Research on Interior Gas Distribution Technologies

Transcription

1 ABSTRACT Results From 20 Years of Research on Interior Gas Distribution Technologies Robert Torbin Manager of Business Development Foster-Miller, Inc. Waltham, Massachusetts U.S.A. Over the last 20 years, the gas industry has experienced many changes in the way natural gas is distributed within residential and commercial buildings. One of the most radical departures from traditional practice is the elevated pressure, corrugated stainless steel tubing (CSST) system. Research results have shown that elevated pressure CSST systems are less expensive to install; provide the consumer with enhanced features not available with conventional low pressure steel piping systems; and provide future expansion options. In the single-family market, these features have successfully increased the gas load per installation. The retrofit of CSST with installed low-pressure, steel pipe systems also encourages more gas usage. GTI sponsored research has supported many innovations in this technical area including: Gas Load Center: A prefabricated piping assembly and enclosure that focuses consumer attention on the addition of more appliances. Gas Convenience Outlet: A quick-connect coupling with an integrated manual valve and safety interlock used with movable appliances. Larger diameter (up to 50 mm): Expanded the use of CSST in the commercial and residential markets. The benefits of using CSST systems are clearly demonstrated based on numerous field studies performed in a wide range of new and existing buildings and applications. INTRODUCTION Over the last 20 years, the gas industry has experienced many changes in the way natural gas is distributed within residential buildings. One of the most radical departures from traditional methods is the elevated pressure, corrugated stainless steel tubing (CSST) system. Since 1983, the Gas Research Institute (now known as the Gas Technology Institute or GTI) has supported numerous research projects aimed at addressing the technical, economic and institutional issues affecting the introduction of innovative interior gas distribution products. GTI sponsored research results have shown that 2 psi (13.8 kpa) flexible gas piping systems can be less expensive to install; will provide the consumer with enhanced features that are not available with conventional low pressure steel piping systems; and will provide future expansion options typically not associated with gas piping systems. 1 M02-028

2 FLEXIBLE GAS PIPING SYSTEM CSST is commercially available in a variety of sizes ranging from in. to 2 in. (9.5 mm to 50.8 mm) internal diameter. The tubing is packaged in long coils on spools (that facilitate the dispensing of the tubing) and the coils are available in lengths varying from 100 ft to 500 ft (30m to 150m), depending on tubing diameter. Reusable mechanical fittings are provided to connect the tubing with other components within the overall gas distribution network. The tubing can be easily cut and field assembled with the mating fittings using standard hand tools. All fittings are required to incorporate standard NPT threads for connection to conventional plumbing components and appliances. Unlike conventional plumbing products, CSST is sold as a system and is certified in accordance with a nationally recognized standard known as ANSI LC-1. The system, as shown in Figure 1, includes the tubing, fitting and certain other necessary components used within the overall gas piping system such as: Figure 1. CSST System Components (Photo courtesy of Titeflex Corporation) 2 M02-028

3 Multiport manifolds. Appliance termination outlets. Special metallic striker plates. Pressure regulator (for elevated pressure systems). The CSST manufacturer is also responsible for preparing and distributing a system design and installation manual, as well as providing training for all installers. The installation instructions must be revised and reprinted as needed, and the trained installers kept abreast of all pertinent changes to the hardware, installation practices and sizing methods. CSST can be used in either conventional low pressure or elevated pressure [up to 5 psi (34.5 kpa)] systems. The choice of design pressure and allowable pressure drop will depend on several factors, including the application, availability of elevated pressure in the street, local plumbing code restrictions, required gas load, delivery distance, and the locations of the appliances within the building. Regardless of the system pressure, the gas distribution network can be installed in one of three arrangements: either in series, in parallel, or a combination of the two. A series layout, like the design of a conventional steel pipe system, is best described as one main feed line with branch lines (or drops located along the main) supplying individual appliances. Thus, the gas load will vary along the main as each appliance line branches off. In the parallel arrangement, a main line is installed from the meter to a multiport distribution manifold. The manifold can be located near the meter or inside the house near the major gas appliances. From this manifold, independent, parallel lines are run to each appliance. Compared to rigid steel pipe, the installation of CSST has several distinct differences. In most installations, there will be no intermediate joints because the tubing is capable of being installed in one continuous run. This significantly reduces not only the total number of joints, but it also minimizes the number of potential leak sites. Because most gas piping is field run, the flexibility of the corrugated tubing allows the installer to seek the path of least resistance around existing structural and mechanical obstacles such as floor beams or air ducts. This flexibility eliminates the repetitive measuring, cutting, threading, and joint assembly that are required with steel pipe systems. The dual pressure system has become the preferred (although not mandatory) approach to the design of the gas distribution network when using CSST. Typically, it is used when the gas load exceeds 100 CFH (2.8 m 3 /hr), or there is a significant distance between the gas meter and the gas appliances and the pathways include complex turns and twists. Using Figure 2 as a reference, the system can be described as follows: Natural gas is delivered to the building at street pressure where a service regulator drops the pressure to 2 psi (13.8 kpa) just upstream of the meter. The entire household gas load is then delivered through a single, small diameter line to a centrally located distribution point where a shutoff valve, pressure regulator, and distribution manifold are located. The maximum pressure drop in this portion of the piping network is typically 1 psi (6.9 kpa). 3 M02-028

4 Range/oven R Building wall Manifold Water heater R Furnace Meter 2 psi (14 kpa) available downstream <1/2 psi (3.4 kpa) pressure downstream of regulator R = Shutoff = Service pressure regulator 590-ICDV Figure 2. Typical Dual Pressure System Arrangement The line pressure is reduced from 1 psi to 0.25 psi (6.9 kpa to 1.7 kpa) through the regulator. The outlet pressure can be varied and is typically set by the supplier between 7 to 10 in. WC (1.7 to 2.5 kpa). The gas is then redistributed, at low pressure, through relatively short, independent, parallel lines to each appliance. Finally, the tubing is connected to the appliance, according to local practice. Typically, the pressure drop in this portion of the piping system varies between 0.5 and 3 in. WC. (0.12 and 0.73 kpa) depending on the pressure at the outlet of the line regulator. Experience installing CSST systems identified the need to streamline the assembly and field installation of the distribution manifold and associated components required in an elevated pressure system. Research showed that a prefabricated manifold assembly could significantly reduce the installation time and simplify the design and layout of the piping network. In response to this need, the Gas Load Center was conceived, designed and developed. Because an elevated pressure system can easily accommodate additional appliances after the home is occupied, it also became clear that a convenient, low cost device for connecting those appliances was required. To make the connection to the piping network easier for the homeowner, a quick connect device was developed, and is now sold as the Gas Convenience Outlet. GAS LOAD CENTER The Gas Load Center (GLC) is a prefabricated piping assembly and enclosure box shown in Figure 3. The metallic enclosure is designed to be installed either between two standard wall studs 4 M02-028

5 Figure 3. Gas Load Center 5 M02-028

6 or on a wall surface. When fully installed, the box includes a service shutoff valve, drip leg, line pressure regulator, piping union (to facilitate regulator replacement) and multiport welded steel or cast manifold with mounting bracket and clamps. The entire manifold assembly can be removed from the enclosure to facilitate the mounting of the box between the studs. The enclosure is provided with knockouts for six tubing runs, and can be oriented for tubing runs entering/existing the GLC from above or below. Although the typical manifold configuration is a four port arrangement, it can be customized in terms of the number and size of the ports. For large upscale, single family homes (where many gas appliances are typical) two GLCs can be installed side by side to accommodate the extra load or a second load center can be installed at another location within the house. All manifold components can be assembled at the plumbing contractor s shop prior to field installation. Once assembled, the entire Gas Load Center can be shop inspected and tested for leakage. After the enclosure is installed in a house, the field operation is reduced to installing the meter and appliance tubing runs, and completing the assembly of the fittings. As an option, shutoff valves can be installed at each manifold port to facilitate the servicing of the appliances and any future piping system modifications. The GLC also provides the consumer with other safety features. Each port can be numbered and recorded on a log sheet attached to the unit, so that each appliance connection can be easily identified. Safety information, system sizing data and important telephone numbers can also be listed on a notice located inside the GLC. Although the primary benefit of the Gas Load Center is to reduce the installation cost of the piping system, it can also be a major factor for increasing the natural gas load. The GLC is a visible and attractive feature (heretofore totally lacking in conventional steel piping systems) that focuses consumer attention on the enhanced use options available with this new distribution product. These use options include: The ability to add more gas appliances (spare ports on the manifold) without any major replumbing of the existing piping system. The use of individual appliance shutoff valves conveniently located inside the Gas Load Center. The ability to incorporate home monitoring technology (i.e., smoke and CO detectors) into the gas distribution network through the use of electrically operated shutoff valves. GAS CONVENIENCE OUTLETS The use of 2 psi (13.8 kpa) delivery pressure and flexible tubing to distribute natural gas within homes has increased dramatically during this past decade. On average, over 30 million feet (approximately 10 million meters) of CSST have been sold each year. These systems provide the homeowner with a more extensive and decentralized network of gas piping, and are conducive to the use of gas convenience outlets. The outlets are intended to be used with both movable and portable appliances. Typical applications include clothes dryers, barbecue grills, space heaters, free-standing 6 M02-028

7 range/oven units, outdoor lights, and a variety of new lightweight, countertop cooking appliances. These countertop appliances are used extensively in Japan where gas outlets have been available for several years. Ultimately, the gas outlets may become as common as electrical outlets, including the requirement to preplumb all kitchens and laundry rooms for both gas and electricity. The GTI developed gas outlet has been commercialized by M.B. Sturgis, Inc. The Model 3/375 outlet, shown in Figure 4, has a manual valve with safety interlock integrated with a standard quick connect device. The appliance plug cannot be inserted unless the manual valve is in the closed position. The user can then push the locking collar back, insert the connector plug, and capture the plug by releasing the locking collar. The manual valve can then be opened to start the flow of gas. With the valve in the open position, the interlocking safety cam prevents the removal of the connector plug. The plug can only be removed after the manual valve has been closed, and the locking collar manually retracted by the user. As an additional safety feature, the Model 3/375 has a built-in thermal fuse that prevents the flow of gas if the outlet is exposed to temperatures in excess of 200 F (93 C). The outlet can be mounted either on a wall surface or within the wall cavity (behind the wallboard) with the use of a special mounting enclosure. For outdoor installations, a plastic cover is provided to protect the unit from the weather and other hazards. Figure 4. Gas Convenience Outlet 7 M02-028

8 INSTALLATION CASE STUDIES Although the natural gas industry has seen an impressive national growth in the residential market over the past few years, there are local areas in the United States where new construction is slow and/or the opportunity to add new customers is limited. Such is the case in the inner cities and older suburban communities. However, load growth even in these mature markets is possible. Selling more gas to the existing customer base can significantly increase load. In addition, the ability to easily and quickly convert (a home or business) from propane or electricity to natural gas can also make a large contribute to load growth. Unfortunately, traditional rigid steel pipe has proven to be incompatible in this potentially large, market growth area. Steel piping systems are difficult and expensive to modify in retrofit situations. However, based on twenty years of experience, CSST systems can make the retrofitting of new gas service or the expansion of existing systems as easy as extending the electrical wiring. Especially important to the retrofit market is the use of the existing low pressure system and pressure drop. To accommodate the low pressure/pressure drop, the CSST industry has developed and certified CSST sizes greater than 1 in. (25.4 mm) I.D. (which had been the previous maximum tubing size for many years). Based on changes to the ANSI LC-1 Standard, sizes up to 2 in. (50.8 mm) are now commercially available. In addition, the larger sizes can better deal with the flow capacities associated with commercial and industrial applications. As shown in Table 1, there are a number of suppliers of CSST product in a wide range of sizes. To document the benefits of using CSST to the gas and plumbing industries, Foster-Miller has performed numerous installation time studies. These studies measured the actual cost for the materials and installation labor for the gas piping system in a wide variety of building types and retrofit applications. Installation studies in new construction were completed earlier in the research effort. Retrofit installation studies have been completed as well and have also been wide ranging with many variations. Installations projects have included the simple addition of one more appliance, the expansion of an existing steel pipe system to accommodate a large remodeling job and several appliances, major rehabilitation projects in large multifamily buildings, as well as conversions of electric or propane service to natural gas. Although the results from only a few of these studies are described in this paper, CSST systems, in general, are always more cost-effective than steel pipe systems for retrofit applications. In many cases, gas service would not have been provided if steel pipe were the only solution. Retrofitting steel pipe is prohibitively expensive, in general, and furthermore, it can cause extensive collateral damage to the building interior during the installation process. Single Family Home: Major Expansion of an Existing Gas System (2 Appliances to 8 Appliances) The existing contemporary home was built in 1991 with gas water and space heating systems. The owner, who was undertaking a major remodeling of the home, wished to add six new gas appliances. These included: fireplace log, range/oven unit, clothes dryer, barbecue outlet, and two garage space heaters. The gas load would be more than double, from 208 to 518 cfh (5.8 to 14.5 m 3 /hr). The existing gas equipment was operated at 7 in. WC (1.7 kpa) and connected with 8 M02-028

9 Table 1. Available CSST Sizes by Manufacturer EHD Value # Nominal Diameter (in.) 3/8 3/8 1/2 1/2 3/4 3/ /4 1-1/4 1-1/2 1-1/2 2 2 CSST Manufacturer Ward X X X X X X X Gastite X X X X X X X Omegaflex X X X X X X X Parker X X X X X Tru-Flex X X X X Metal-Fab X X X X X # No EHD value assigned as of 6/01/02 9 M02-028

10 steel pipe. To minimize the disruption to the existing equipment and to be in compliance with the Massachusetts Plumbing Code, a low pressure CSST system was designed. However, to minimize the cost, the gas pressure was actually raised to 13 in. WC (3.2 kpa) with an allowable pressure drop of 6 in. WC (1.4 kpa) and some portions of the new piping system were plumbed using steel pipe. A multiport manifold was installed into the steel pipe system in the mechanical equipment room as shown in Figure 5. Separate parallel CSST lines were installed for the range/oven, the two garage heaters and the clothes dryer/bbq outlets. The installation of the gas piping system required not only gas fitters, but also needed carpenters (for restoration of interior spaces) and electricians (wiring of new appliances). The cost of this project as installed was $3800. The cost estimate for doing the same installation, but only using low pressure steel piping, was $5100. It should be noted that the installation contractor would not have installed some of the same runs with steel pipe due to the cost and difficulty of the restoration. High Rise Multifamily Building: Conversion from all Electric Service to Natural Gas The 14-story Hampden Hall apartment building underwent an eight million dollar renovation that included conversion of the major appliances from electric to gas. This historic 1920 two tower Figure 5. Manifold for New CSST Appliance Runs 10 M02-028

11 building contains 76 housing units. To make the conversion work, Laclede Gas installed a 7 psi (48.3 kpa) welded steel main vertically up the side of the building. The pressure is reduced to 2 psi (13.8 kpa) at each service regulator located on the service balcony on each floor. One service regulator was provided for two or three meters, also located on the service balcony. Downstream of the meter, corrugated stainless steel tubing was used for all of the interior gas distribution. The portion of the gas system from the meter to each apartment was operated at 2 psi (13.8 kpa). Once inside the apartment, the pressure was lowered to 8 in. WC at the gas load center. Most apartments had a furnace, water heater, range/oven and a clothes dryer. Each appliance was served with an independent, parallel CSST gas line connected to a multiport manifold. The biggest driver for the selection of this approach was time. The developer had crucial deadlines for occupancy that affected his financing. The CSST system was the only way to meet the two month time table. In fact, over 7,600 ft (2300m) of CSST was installed within the stipulated schedule. Laclede Gas estimated that the CSST installation required less than 50 percent of the labor needed to install a comparable low pressure steel piping system. This resulted in savings of 35 percent in the total installed cost. Low Rise Multifamily Building: Rehabilitation of Abandoned Building with Entirely New Gas Piping System The abandoned, three story structure was formerly an apartment building with retail shops on the ground level. Although the existing masonry walls were left unchanged, the entire interior space was gutted and repartitioned into 20 small living units. The original building had the traditional low pressure steel piping gas service with all the meters located in a small room in the basement level. The old gas piping network had been removed during the interior rebuilding, and was replaced with a new 2 psi (13.8 kpa) CSST system, starting from the same meter room. Each apartment was provided with a combination space and water heating unit and a range/oven unit. The typical gas load center for these apartments was quite simple. Given the small size of each apartment and the use of only two appliances, there was close similarity between the CSST system and the comparable steel pipe system. However, the complex routing of the piping within the existing and new walls and floors of the building proved the value of the flexible tubing approach. The results from the time and materials study were quite dramatic. As shown in Figure 6, the average time to install the CSST system was 1.90 hr per apartment. Compared to the average time for the steel pipe system (8.5 hr), the CSST was installed in 78 percent less time. The total installed cost savings of the CSST system over the steel pipe approach was 25 percent. Low Rise Multifamily Building: Conversion from Centrally Heated Oil to Decentralized Gas Many of the multifamily buildings in Brooklyn, NY are centrally heated with fuel oil. Many previous research studies have proven that individual renter responsibility and control of the energy usage will result in lower energy use compared to centralized services without cost constraints. However, the cost of these conversions is made more difficult to justify when faced with the high cost of installing individual apartment piping for natural gas service. Each floor has four apartments built around a central corridor and staircase. The central system was removed as part of a general 11 M02-028

12 9 8 Average Installation Time for One Unit Standard Man Hours (SMH) SMH 1.89 SMH 2.17 SMH 0 Steel Pipe System Corrugated Tubing System Copper Tubing System Figure 6. Average Installation Time per Apartment 450-OH reconstruction of the interior space. In it place, individual gas fired hydronic boiler units were installed in the basement. Each boiler is served by its own gas meter. A tee fitting was installed at the meter to permit separate CSST lines to be installed to each boiler and to each apartment for the range/oven unit. The entire installation of the gas piping system was accomplished by two plumbers and a part time helper. Because of the extreme low pressure conditions in the streets of Brooklyn, only a low pressure piping system was possible. According to New York City Plumbing Code, the total head loss allowed from the meter to the range/oven is 0.5 in. WC (0.12 kpa). This necessitated the use of larger sized CSST than would have been needed for a 2 psi (13.8 kpa) system. The time required to install the CSST system was measured at 66 hr. The total time needed to install a comparable steel pipe system was calculated to be 128 hr. The total installed cost savings were much smaller due to the higher cost of materials for the CSST system. Although the savings were calculated to be only 3 percent, the actual savings are understated. The time study does not include any time for locating and repairing leaks in the piping system. For steel pipe systems, 10 percent additional cost is typically added to the price to accommodate this highly probable occurrence. Commercial Building: Installation of New Gas Piping Network for a Laboratory Testing Facility The decision by CSA to move its operations to an existing 15,000 ft 2 commercial building in southern California brought with it the need to completely re-pipe the facility. CSA provides appliance testing services to the gas industry, and has the need for eleven test stations. Each station is supplied 12 M02-028

13 with four different gases: natural gas, LP gas, butane and a butane/air mixture. The natural gas and butane/air are supplied at 14 in. WC (3.4 kpa) and the propane and butane are supplied at 21 in. WC (5.1 kpa). Using steel pipe for this experimental setup would be extremely expensive for two reasons. The close quarters around each test station would create a rats nest of pipe and pipe supports. Given the need for seismic restraints on these pipes, the cost and complexity would be further exacerbated. The choice of CSST eliminated all these concerns. The lightweight and flexible nature of the tubing allowed the use of simple unistruts for support and organizing the numerous tubing runs. The unistrut, while providing effective support, is also relatively inexpensive. Figures 7 and 8 give some appreciation for the complexity of the piping network and some of the installation issues associated with the design of the piping within the open space configuration of the building. Results from the installation study were dramatic. The CSST system was installed in 40 percent less time and with more than $8,000 in total savings compared to the steel pipe approach. HOME AUTOMATION SYSTEMS Office and home automation are evolving with similar goals to serve different building markets. They both offer facilities for the interoperation of systems that were formerly independent, including life safety, heating and cooling, lighting, and the distribution and utilization of energy, including natural gas. The technology that implements these automation features is typically electronic and microprocessorbased, with a strong bias towards all-electric homes and offices. Therefore, the gas industry faces three immediate challenges in attempting to remain competitive with electricity in these emerging markets: An adaptable interior gas energy distribution network is needed that can be integrated with the electrical network, and make gas service available throughout any given building in a costeffective manner. It is essential to provide the consumer with enhanced use and safety options for gas applications. Natural gas appliances must be designed for compatibility with an automation environment. This requires capabilities for transmitting, receiving and processing data and control signals using one of the emerging standards specifying the formal rules for communications. The integration of gas with home and office automation must be available both to new and existing structures. There are more than 50 million homes in the United States currently using natural gas, while the number of new gas-fueled houses constructed each year is only about 600,000. The impending widespread use of automation technology clearly indicates that the blind acceptance of business as usual including the use of low pressure steel pipe technology for the distribution of natural gas must be rethought. The gas piping must be viewed as an energy distribution network, and not just a plumbing subsystem. With flexible tubing arranged in a parallel fashion from a distribution center, operated at elevated pressures, and connected to appliances through quick connect outlets, many analogies can be made between this approach and the way electrical energy is distributed. 13 M02-028

14 Figure 7. Manifold and Regulator Station for Four Test Fuels Figure 8. Overview of Gas Piping Installation 14 M02-028

15 There are many communications protocols appropriate for home and office automation. At this time, CEBus is one of the strongest candidate protocols. CEBus and other communication systems provides a digital data communications network that links appliances and monitoring system components, such as switches, sensors and control panels, allowing the exchange of commands, operating data and equipment status. These communication protocols have been designed to accommodate a variety of communication media, including: the power line; twisted pair wires; coaxial cable; infrared signaling; radio frequency signaling; and fiber optics. Foster-Miller has proposed a framework for the integrated of the interior gas piping system with the home and/or office automation system called Gas-Wise. Key components of the Gas-Wise system include the service entry, the intelligent load center, and smart gas appliance outlets. The integration of the gas piping system with home and office automation enhances the basic functions of a conventional gas piping system, including energy metering, interior gas distribution, system control and monitoring, and consumer safety. Energy Metering: The Gas-Wise system is designed to accommodate either a single or multiple metering devices. Multiple flow sensors/metering devices will allow individual analysis of appliance gas consumption, as well as the measurement of the total gas load for billing purposes. The use of a remote read meter with electronic interfaces would be standard in the Gas-Wise system. The main meter is part of the Service Entry that serves as the utility gateway between the Gas-Wise communications network and the utility s distribution automation system. Gas Distribution: All gas piping system components of the Gas-Wise system are interconnected with semi-rigid tubing, and appliances connected through smart convenience gas outlets. These outlets permit quick plug-in appliance connectors, and also contain interfaces for the electronic controls and sensors within each appliance. The smart outlets determine gas load requirements, and allow gas to flow only when a valid request (by the appliance) for service is made. The decentralized distribution network allows gas usage anywhere inside the structure. Control and Monitoring: The principal function of the control and monitoring subsystems is safety. The overall system is broken down into zones, and each zone is monitored separately, but the control can be applied either by zone or for the entire network. The brains of the control and monitoring system is the Gas Load Center which contains the microprocessors, sensors and hardware necessary to supervise the gas flow throughout the system. The GLC checks the status of components within the Gas-Wise network, such as regulators, valves, piping, and appliances, and also receives signals from sensors outside the system, such as a smoke detector, thermostat or security system. The system determines if an unsafe condition exists, and engages the necessary safety devices (such as a shutoff valve) isolating a particular zone or shutting down the gas flow to the entire house. Consumer Safety: In addition to the safety aspects of the control and monitoring system, the Gas- Wise system addresses other safety issues. Each connected appliance is integrated into the network and allows for constant monitoring of the gas consumption, combustion by-products and the operation of mechanical components. Deviations from established operational norms could be charted and corrective action taken automatically if the condition persists beyond a predetermined time. Other safety features of the network include: 15 M02-028

16 Thermal fuses to prevent gas escape from individual gas lines during fires. Tunable excess flow devices to protect against major and minor line breaks. Tamper sensors to monitor unauthorized changes to the system. The introduction of home and building automation may significantly influence the expansion of the natural gas market. An integrated automation and gas piping system offers many advantages both to consumers and to local gas companies. Consumers will have more access options with enhanced safety, and thereby, more opportunities for using gas appliances. As a result, gas companies will increase sales while decreasing operating costs by linking distribution automation with home and office automation. These benefits should help convince local utilities to make the necessary investments in automation and encourage the housing and building industries to do the same to form an integrated network. CONCLUSIONS In highly competitive environments, innovative methods for gas delivery have proven to be a sales advantage to local gas companies. In the upscale single family market, the combined use of the CSST system, elevated operating pressure, gas load centers and outlets has been very successful in maximizing gas load per house for new installation. In many cases, 8 to 12 appliances are routinely installed in these types of homes. Future tie-ins with home automation/monitoring systems; the ability to easily retrofit the piping network for new load additions; and the significant cost advantage of CSST for major rehabilitation projects and fuel conversion opportunities have more than justified any increase in material costs for the CSST, GLC and outlets. The availability of corrugated stainless steel tubing systems has changed the rules for evaluating options in the residential and commercial markets for new construction, retrofit, remodeling and rehabilitation. In the retrofit markets, it is particularly difficult to cost-effectively install and/or extend steel piping systems. The complexity of the building geometry and the need to minimize the damage to the existing interior space are factors that make rigid steel pipe difficult to use and expensive to specify. Lost market growth can be recaptured through the use of flexible gas piping that makes gas as easy to install as electric wiring. CSST essentially allows the plumber to wire the building for gas. Results from numerous field installation studies in a wide variety of building types and retrofit applications confirm this claim. Typically, CSST can be installed in less than half the time needed for steel pipe. For many applications, the total installed cost for CSST will be 50 to 75 percent lower than for steel pipe. It has been noted on several occasions, that installers would not even attempt to use steel pipe for many of the installations that were included in this paper. In general, steel pipe becomes cost prohibitive when the complexity of the building geometry is too great, and the potential exists to damage the existing interior walls and floors. What has been lacking in the past, and what these new innovative products bring, is a marketing focus on infrastructure benefits rather than the conventional wisdom of selling gas based on comfort/ energy savings. Flexible gas piping operating at 2 psi (34.5 kpa) pressure, distributed throughout the home through a GLC, and supplying appliances through quick connect outlets is a system concept 16 M02-028

17 and represents enabling technology. Like natural gas itself, enabling technology is a fundamental backbone that allows other benefits to be realized. A homeowner who appreciates how electricity is distributed throughout the house will also realize that the gas can be similarly distributed. Once the consumer realizes that gas can be easily made available anywhere in the home, then a demand for more gas service is sure to follow. ACKNOWLEDGMENTS Mr. Paul Belkus of Foster-Miller, Inc. was the Principal Investigator for all of the field installation studies and was the Project Manger for much of the research that is reported in this paper. Unfortunately, Paul was killed in a tragic motorcycle accident in April This paper is dedicated to his long-standing dedication to gas industry research, in general, and to the gas piping program, in particular. The author also wishes to acknowledge the Gas Research Institute/Gas Technology Institute (the principal project sponsor for many years) for its support of this research and to Mr. Marlon McClinton for his staunch and long-standing commitment to and support of gas piping research. 17 M02-028