Optimizing Hydronic System Performance in Residential Applications

Research output: NRELSubcontract Report

Abstract

Even though new homes constructed with hydronic heat comprise only 3% of the market (US Census Bureau 2009), of the 115 million existing homes in the United States, almost 14 million of those homes (11%) are heated with steam or hot water systems according to 2009 US Census data. Therefore, improvements in hydronic system performance could result in significant energy savings in the US. Whenoperating properly, the combination of a gas-fired condensing boiler with baseboard convectors and an indirect water heater is a viable option for high-efficiency residential space heating in cold climates. Based on previous research efforts, however, it is apparent that these types of systems are typically not designed and installed to achieve maximum efficiency. Furthermore, guidance on properdesign and commissioning for heating contractors and energy consultants is hard to find and is not comprehensive. Through modeling and monitoring, CARB sought to determine the optimal combination(s) of components - pumps, high efficiency heat sources, plumbing configurations and controls - that result in the highest overall efficiency for a hydronic system when baseboard convectors are used asthe heat emitter. The impact of variable-speed pumps on energy use and system performance was also investigated along with the effects of various control strategies and the introduction of thermal mass.
Original languageAmerican English
Number of pages83
StatePublished - 2013

Bibliographical note

Work performed by Consortium for Advanced Residential Buildings, Norwalk, Connecticut

NREL Publication Number

  • NREL/SR-5500-60200

Other Report Number

  • DOE/GO-102013-4108

Keywords

  • AFUE
  • baseboard
  • buffer tank
  • Building America
  • CARB II
  • condensing boilers
  • cycling
  • efficiency
  • gas-fired
  • hot water
  • HVAC
  • hydronic systems
  • indirect tank
  • modulating
  • optimization
  • recovery
  • residential
  • residential buildings
  • return temperature
  • standby losses
  • thermostat setback
  • variable speed pumps

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