Research Project Information

Research Project Summary Information

Hydronic Heating and Domestic Hot Water Efficiency Study(ST8916-1)

Brookhaven National Lab


It is estimated that about two million single family homes in New York State use hydronic boilers for heating. Residential boilers vary widely in seasonal efficiency based on heat exchanger effectiveness, burner type, and controls. Controls used on hydronic boilers range in quality from simple on-off, aquastat switches to complex, boiler temperature reset controls that adjust supply temperature based on outside temperature. The most common types of water heating equipment used in New York State homes that are heated with boilers include; built-in tankless coils, indirect water heaters, direct gas and oil-fired water heaters, and electric resistance water heaters. USDOE Annual Fuel Utilization Efficiency (AFUE) ratings for boilers are widely known to be poor indicators of actual seasonal performance. The AFUE test procedure does not give proper credit for thicker (European style) boiler jacket insulation, low-temperature condensing heat exchangers, advanced controls, and other efficiency features. Also, AFUE ratings for boilers, as well as USDOE Energy Factor (EF) ratings for water heaters, are not applicable to residential, combined, boiler/domestic hot water systems. There is a significant lack of accurate energy efficiency information available to heating contractors and consumers who wish to install or use combined heating and domestic water systems.

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Project Description

Brookhaven National Laboratory (BNL) is testing an array of boilers and water heating equipment to identify equipment designs and system configurations that can achieve energy savings for consumers. This project is focusing on hydronic technologies. Under Phase I of the project, BNL is using previously-proven, laboratory testing procedures along with simulated load profiles that are known to match real-world conditions, to evaluate the thermal efficiency and electricity consumption of typical equipment found in existing homes. Phase II of the project will include testing of high-efficiency, state-of-the-art technologies that have recently become commercially available. The state-of-the-art technologies will include a number of new products developed by NYS manufacturers under the NYSERDA Heating and Cooling program element. Efficiency results would then be disseminated through a public outreach program. The National Oil-heat Research Alliance (NORA) will take the lead in publishing results for oil-fired equipment. NORA has committed to the preparation and publication of consumer education materials that will contain the information developed under this project. Other organizations such as ACEEE have expressed interest in obtaining and distributing the described information for both fuel types.


Benefits include energy savings for heating and domestic hot water in single family homes. Based on the information gained from this research, program staff will be able to cite savings estimates with a high level of confidence and convey such information to NYSERDA contractor networks and the public. Additionally, such information will be shared with CEE and NEEP for distribution to their members.

Project Results


Brookhaven National Lab
32 Lewis Road Building 130
Upton, NY 11973

Principle Investigator

Tom Butcher

Universities Involved


Project Type:

Research Study

Technologies Types:

Building Systems
Heating, Ventilation, & Air Conditioning

NYSERDA Contact Information

Nathan Russell


R&D - Buildings Research

Contract Details

Start Date: 1/11/2010
Project Status: Active
Contract Number: ST8916-1

Last Updated: 9/15/2014