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Low-Cost Solar Water Heating Research and Development Roadmap

Description: The market environment for solar water heating technology has changed substantially with the successful introduction of heat pump water heaters (HPWHs). The addition of this energy-efficient technology to the market increases direct competition with solar water heaters (SWHs) for available energy savings. It is therefore essential to understand which segment of the market is best suited for HPWHs and focus the development of innovative, low-cost SWHs in the market segment where the largest opportunities exist. To evaluate cost and performance tradeoffs between high performance hot water heating systems, annual energy simulations were run using the program, TRNSYS, and analysis was performed to compare the energy savings associated with HPWH and SWH technologies to conventional methods of water heating.
Date: August 1, 2012
Creator: Hudon, K.; Merrigan, T.; Burch, J. & Maguire, J.
Partner: UNT Libraries Government Documents Department

Solar Water Heaters - The Next Generation

Description: The U.S. Department of Energy is pursuing an aggressive goal to cut the cost of solar water-heating systems in half. Replacing metal and glass components with less expensive plastic ones is a key strategy for that goal. This is a short (2-page) fact sheet about new technologies for solar water heaters.
Date: March 30, 2001
Creator: Burch, J.
Partner: UNT Libraries Government Documents Department

Demand Response Performance of GE Hybrid Heat Pump Water Heater

Description: This report describes a project to evaluate and document the DR performance of HPWH as compared to ERWH for two primary types of DR events: peak curtailments and balancing reserves. The experiments were conducted with GE second-generation “Brillion”-enabled GeoSpring hybrid water heaters in the PNNL Lab Homes, with one GE GeoSpring water heater operating in “Standard” electric resistance mode to represent the baseline and one GE GeoSpring water heater operating in “Heat Pump” mode to provide the comparison to heat pump-only demand response. It is expected that “Hybrid” DR performance, which would engage both the heat pump and electric elements, could be interpolated from these two experimental extremes. Signals were sent simultaneously to the two water heaters in the side-by-side PNNL Lab Homes under highly controlled, simulated occupancy conditions. This report presents the results of the evaluation, which documents the demand-response capability of the GE GeoSpring HPWH for peak load reduction and regulation services. The sections describe the experimental protocol and test apparatus used to collect data, present the baselining procedure, discuss the results of the simulated DR events for the HPWH and ERWH, and synthesize key conclusions based on the collected data.
Date: July 1, 2013
Creator: Widder, Sarah H.; Parker, Graham B.; Petersen, Joseph M. & Baechler, Michael C.
Partner: UNT Libraries Government Documents Department

Impacts of Water Quality on Residential Water Heating Equipment

Description: Water heating is a ubiquitous energy use in all residential housing, accounting for 17.7% of residential energy use (EIA 2012). Today, there are many efficient water heating options available for every fuel type, from electric and gas to more unconventional fuel types like propane, solar, and fuel oil. Which water heating option is the best choice for a given household will depend on a number of factors, including average daily hot water use (total gallons per day), hot water draw patterns (close together or spread out), the hot water distribution system (compact or distributed), installation constraints (such as space, electrical service, or venting accommodations) and fuel-type availability and cost. While in general more efficient water heaters are more expensive than conventional water heating technologies, the savings in energy use and, thus, utility bills can recoup the additional upfront investment and make an efficient water heater a good investment over time in most situations, although the specific payback period for a given installation will vary widely. However, the expected lifetime of a water heater in a given installation can dramatically influence the cost effectiveness and savings potential of a water heater and should be considered, along with water use characteristics, fuel availability and cost, and specific home characteristics when selecting the optimum water heating equipment for a particular installation. This report provides recommendations for selecting and maintaining water heating equipment based on local water quality characteristics.
Date: November 1, 2013
Creator: Widder, Sarah H. & Baechler, Michael C.
Partner: UNT Libraries Government Documents Department

Comparison of natural convection heat exchangers for solar water heating systems

Description: Thermosyphon heat exchangers are used in indirect solar water heating systems to avoid using a pump to circulate water from the storage tank to the heat exchanger. In this study, the authors consider the effect of heat exchanger design on system performance. They also compare performance of a system with thermosyphon flow to the same system with a 40W pump in the water loop. In the first part of the study, the authors consider the impact of heat exchanger design on the thermal performance of both one- and two-collector solar water heaters. The comparison is based on Solar Rating and Certification Corporation (SRCC) OG300 simulations. The thermosyphon heat exchangers considered are (1) a one-pass, double wall, 0.22 m{sup 2}, four tube-in-shell heat exchanger manufactured by AAA Service and Supply, Inc., (the Quad-Rod); (2) a two-pass, double wall, 0.2 m{sup 2}, tube-in-shell made by Heliodyne, Inc., but not intended for commercial development; (3) a one-pass, single wall, 0.28 m{sup 2}, 31 tube-in-shell heat exchanger from Young Radiator Company, and (4) a one-pass single-wall, 0.61 m{sup 2}, four coil-in-shell heat exchanger made by ThermoDynamics Ltd. The authors compare performance of the systems with thermosyphon heat exchangers to a system with a 40 W pump used with the Quad-Rod heat exchanger. In the second part of the study, the effects of reducing frictional losses through the heat exchanger and/or the pipes connecting the heat exchanger to the storage tank, and increasing heat transfer area are evaluated in terms of OG300 ratings.
Date: September 15, 1998
Creator: Davidson, J. & Liu, W.
Partner: UNT Libraries Government Documents Department

Expert Meeting Report: Recommendations for Applying Water Heaters in Combination Space and Domestic Water Heating Systems

Description: The topic of this meeting was 'Recommendations For Applying Water Heaters In Combination Space And Domestic Water Heating Systems.' Presentations and discussions centered on the design, performance, and maintenance of these combination systems, with the goal of developing foundational information toward the development of a Building America Measure Guideline on this topic. The meeting was held at the Westford Regency Hotel, in Westford, Massachusetts on 7/31/2011.
Date: July 1, 2012
Creator: Rudd, A.; Ueno, K.; Bergey, D. & Osser, R.
Partner: UNT Libraries Government Documents Department

Comparison of Advanced Residential Water Heating Technologies in the United States

Description: Gas storage, gas tankless, condensing, electric storage, heat pump, and solar water heaters were simulated in several different climates across the US installed in both conditioned and unconditioned space and subjected to several different draw profiles. While many preexisting models were used, new models of condensing and heat pump water heaters were created specifically for this work.
Date: May 1, 2013
Creator: Maguire, J.; Fang, X. & Wilson, E.
Partner: UNT Libraries Government Documents Department

The LBNL Water Heater Retail Price Database

Description: Lawrence Berkeley National Laboratory developed the LBNL Water Heater Price Database to compile and organize information used in the revision of U.S. energy efficiency standards for water heaters. The Database contains all major components that contribute to the consumer cost of water heaters, including basic retail prices, sales taxes, installation costs, and any associated fees. In addition, the Database provides manufacturing data on the features and design characteristics of more than 1100 different water heater models. Data contained in the Database was collected over a two-year period from 1997 to 1999.
Date: October 1, 2000
Creator: Lekov, Alex; Glover, Julie & Lutz, Jim
Partner: UNT Libraries Government Documents Department

Upper Sand Mountain Parish Solar Construction Workshops. Final performance report

Description: The Upper Sand Mountain Parish continues to employ its initial strategy for involving high school vocational students with the pre cutting and instructional assembly aid to area families. The parish project works with high school vocational classes in pre fabbing solar devices into kit form. Then, students are employed to serve as instructors for Saturday construction workshops at the local electric cooperative. Trained teams of older and unemployed adults work with youth in building solar greenhouses for those able to pay labor. Over three years, the project has assisted and built 50 to 60 attached solar greenhouses with construction teams realizing in excess of $26,000 in labor for newly developed skills. The project continues to assist owners in monitoring and developing horticulturally as well as energy producing greenhouses. During the spring of 1982, the parish assisted greenhouse owners in marketing over 60,000 bedding plants worth over $3000. Monthly Greenhouse Owner Fellowship meetings have been a helpful setting for sharing of ideas and exchange of insights. A low interest solar loan fund, offering 5% loans for three years, has assisted over 30 families in going solar. The principle for this revolving fund has almost reached the $15,000 mark. The track record for loan repayments has been exceptional. Through workshops and tours we have aquainted hundreds of people across the southeast with low cost/low technology solar projects and a workable strategy for involving community groups and students in them. With church involvement, we have provided over $25,000 in grants to over 200 area families. Workshop information and plans are available to those interested for bread box solar water heaters, food dryers, window box collectors, insulation panels, and greenhouses.
Date: February 1, 1983
Partner: UNT Libraries Government Documents Department

Energy Efficiency Design Options for Residential Water Heaters: Economic Impacts on Consumers

Description: The U.S. Department of Energy (DOE) recently completed a rulemaking process in which it amended the existing energy efficiency standards for residential water heaters. A key factor in DOE?s consideration of new standards is the economic impacts on consumers. Determining such impacts requires a comparison of the additional first cost of energy efficiency design options with the savings in operating costs. This paper describes the method used to conduct the life-cycle cost (LCC) and payback period analysis for gas and electric storage water heaters. It presents the estimated change in LCC associated with more energy-efficient equipment, including heat pump electric water heaters and condensing gas water heaters, for a representative sample of U.S. homes. The study included a detailed accounting of installation costs for the considered design options, with a focus on approaches for accommodating the larger dimensions of more efficient water heaters. For heat pump water heaters, the study also considered airflow requirements, venting issues, and the impact of these products on the indoor environment. The results indicate that efficiency improvement relative to the baseline design reduces the LCC in the majority of homes for both gas and electric storage water heaters, and heat pump electric water heaters and condensing gas water heaters provide a lower LCC for homes with large rated volume water heaters.
Date: November 24, 2010
Creator: Lekov, Alex; Franco, Victor; Meyers, Steve; Thompson, Lisa & Letschert, Virginie
Partner: UNT Libraries Government Documents Department

Realistic Hot Water Draw Specification for Rating Solar Water Heaters: Preprint

Description: In the United States, annual performance ratings for solar water heaters are simulated, using TMY weather and specified water draw. A more-realistic ratings draw is proposed that eliminates most bias by improving mains inlet temperature and by specifying realistic hot water use. This paper outlines the current and the proposed draws and estimates typical ratings changes from draw specification changes for typical systems in four cities.
Date: June 1, 2012
Creator: Burch, J.
Partner: UNT Libraries Government Documents Department

Revisions to the SRCC Rating Process for Solar Water Heaters: Preprint

Description: In the United States, annual performance ratings for solar water heaters are computed with component-based simulation models driven by typical meteorological year weather and specified water draw. Changes in the process are being implemented to enhance credibility through increased transparency and accuracy. Changes to the process include using a graphical rather than text-based model-building tool, performing analytical tests on all components and systems, checking energy balances on every component, loop, and system at every time step, comparing the results to detect outliers and potential errors, and documenting the modeling process in detail. Examples of changes in ratings are shown, along with analytical and comparative testing results.
Date: June 1, 2012
Creator: Burch, J.; Huggins, J.; Long, S. & Thornton, J.
Partner: UNT Libraries Government Documents Department

Residential hot water distribution systems: Roundtablesession

Description: Residential building practice currently ignores the lossesof energy and water caused by the poor design of hot water systems. Theselosses include: combustion and standby losses from water heaters, thewaste of water (and energy) while waiting for hot water to get to thepoint of use; the wasted heat as water cools down in the distributionsystem after a draw; heat losses from recirculation systems and thediscarded warmth of waste water as it runs down the drain. Severaltechnologies are available that save energy (and water) by reducing theselosses or by passively recovering heat from wastewater streams and othersources. Energy savings from some individual technologies are reported tobe as much as 30 percent. Savings calculations of prototype systemsincluding bundles of technologies have been reported above 50 percent.This roundtable session will describe the current practices, summarizethe results of past and ongoing studies, discuss ways to think about hotwater system efficiency, and point to areas of future study. We will alsorecommend further steps to reduce unnecessary losses from hot waterdistribution systems.
Date: August 1, 2002
Creator: Lutz, James D.; Klein, Gary; Springer, David & Howard, Bion D.
Partner: UNT Libraries Government Documents Department

Solar hot water systems for the southeastern United States: principles and construction of breadbox water heaters

Description: The use of solar energy to provide hot water is among the easier solar technologies for homeowners to utilize. In the Southeastern United States, because of the mild climate and abundant sunshine, solar energy can be harnessed to provide a household's hot water needs during the non-freezing weather period mid-April and mid-October. This workbook contains detailed plans for building breadbox solar water heaters that can provide up to 65% of your hot water needs during warm weather. If fuel costs continue to rise, the annual savings obtained from a solar water heater will grow dramatically. The designs in this workbook use readily available materials and the construction costs are low. Although these designs may not be as efficient as some commercially available systems, most of a household's hot water needs can be met with them. The description of the breadbox water heater and other types of solar systems will help you make an informed decision between constructing a solar water heater or purchasing one. This workbook is intended for use in the southeastern United States and the designs may not be suitable for use in colder climates.
Date: February 1, 1983
Partner: UNT Libraries Government Documents Department

Prototype solar heated hot water systems and double-walled heat exchangers. Progress report

Description: A collection of quarterly and monthly reports from Elcam, Inc., covering progress made from January 1, 1978, through September 30, 1978, is presented. Elcam, is developing two solar-heated hot water prototype systems and two heat exchangers. This effort consists of development, manufacture, installation, maintenance, problem resolution, and system evaluation.
Date: October 1, 1978
Partner: UNT Libraries Government Documents Department

Freeze-protection loop for direct solar-water-heating systems. Final report

Description: Even a one-time freeze condition can do destructive damage to a direct solar water heating system. The project funded under grant DE-FG4480R4, 1-1-80 to 8-1-81, proposed to demonstrate a simple installation procedure whereby thermosiphoning warm water from storage would prevent solar collectors from freezing. Installing the freeze protection loop in owner maintained solar systems was inconclusive. Owners were not attentive to freeze warnings or did not understand the simple instructions. A controlled situation was established using a refrigerator to produce below freezing temperatures. Experiments conducted with this equipment showed that the thermosiphoning principle could not be relied on to prevent freezing. Thermosiphoning cannot be relied on to prevent freezing in a direct solar water heating system. The direct system is an effective means of heating water in north Florida, but the system must be drained, either manually or automatically, to provide reliable system protection.
Date: November 4, 1981
Partner: UNT Libraries Government Documents Department

Windjammer solar-water-heating system. Final technical report

Description: The results of the Windjammer Solar-Water-Heating System tests showed that it was not as an efficient system as a comparable conventional system for converting solar energy into heat energy. However, it was determined that the innovative mode used less electric back-up energy for water heating. Reduced fossil fuel energy consumption being the ultimate objective of a solar water heating, the principle employed has been shown to be a workable energy saving concept. The differential mode of temperature control emerged as the more efficient mode of operation for the innovative system and under comparable conditions is projected to be nearly equivalent to the conventional solar system. Although the concept has proven workable, the costs feasible, and the potential for considereable improvements exists, additional research and development is needed to advance the design into its most practical application.
Date: April 1, 1982
Creator: Windham, J.R.
Partner: UNT Libraries Government Documents Department

An investigation of photovoltaic powered pumps in direct solar domestic hot water systems

Description: The performance of photovoltaic powered pumps in direct solar domestic hot water (PV-SDHW) systems has been studied. The direct PV- SDHW system employs a photovoltaic array, a separately excited DC- motor, a centrifugal pump, a thermal collector, and a storage tank. A search methodology for an optimum PV-SDHW system configuration has been proposed. A comparison is made between the long-term performance of a PV-SDHW system and a conventional SDHW system operating under three control schemes. The three schemes are: an ON-OFF flow controlled SDHW system operating at the manufacturer-recommended constant flow rate, and a linear proportional flow controlled SDHW system with the flow proportional to the solar radiation operating under an optimum proportionality. 13 refs., 6 figs.
Date: September 1, 1996
Creator: Al-Ibrahim, A.M.; Klein, S.A.; Mitchell, J.W. & Beckman, W.A.
Partner: UNT Libraries Government Documents Department

Colorado State University program for developing, testing, evaluating and optimizing solar heating systems. Project status report, October 1995--November 1995

Description: This document is the October/November 1995 project status report of the Colorado State University Program for developing, testing, evaluating and optimizing solar heating systems. Integrated tank/heat exchanger modeling is discussed, as well as advanced residential solar hot water systems. A paper to be presented at the 1996 International Solar Energy Conference is included. The subject of this paper is rating and certification of domestic water heating systems.
Date: December 1, 1995
Partner: UNT Libraries Government Documents Department