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Hydronic Baseboard Thermal Distribution System with Outdoor Reset Control to Enable the Use of a Condensing Boiler.

DE200515010018

Publication Date	2004
Personal Author	Butcher, T. A.
Page Count	36
Abstract	Use of condensing boilers in residential heating systems offers the potential for significant improvements in efficiency. For these to operate in a condensing mode the return water temperature needs to be about 10 degrees below the saturation temperature for the flue gas water vapor. This saturation temperature depends on fuel type and excess air and ranges from about 110 F to 135 F. Conventional baseboard hydronic distribution systems are most common and these are designed for water temperatures in the 180 F range, well above the saturation temperature. Operating strategies which may allow these systems to operate in a condensing mode have been considered in the past. In this study an approach to achieving this for a significant part of the heating season has been tested in an instrumented home. The approach involves use of an outdoor reset control which reduces the temperature of the water circulating in the hydronic loop when the outdoor temperature is higher than the design point for the region. Results showed that this strategy allows the boiler to operate in the condensing region for 80% of the winter heating season with oil, 90% with propane, and 95% with gas, based on cumulative degree days. The heating system as tested combines space heating and domestic hot water loads using an indirect, 40 gallon tank with an internal heat exchanger.
Keywords	Boilers Residential buildings Thermal efficiency Heat exchangers Space heating Energy efficiency Hot water Propane Vapor condensation Design Performance
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Brookhaven National Lab., Upton, NY. Dept. of Energy Sciences and Technology.; Department of Energy, Washington, DC. Office of Building Technology.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC. Office of Building Technology.
Document Type	Technical Report
NTIS Issue Number	200518

Hydronic Baseboard Thermal Distribution System with Outdoor Reset Control to Enable the Use of a Condensing Boiler.

Hydronic Baseboard Thermal Distribution System with Outdoor Reset Control to Enable the Use of a Condensing Boiler.
DE200515010018

Publication Date	2004
Personal Author	Butcher, T. A.
Page Count	36
Abstract	Use of condensing boilers in residential heating systems offers the potential for significant improvements in efficiency. For these to operate in a condensing mode the return water temperature needs to be about 10 degrees below the saturation temperature for the flue gas water vapor. This saturation temperature depends on fuel type and excess air and ranges from about 110 F to 135 F. Conventional baseboard hydronic distribution systems are most common and these are designed for water temperatures in the 180 F range, well above the saturation temperature. Operating strategies which may allow these systems to operate in a condensing mode have been considered in the past. In this study an approach to achieving this for a significant part of the heating season has been tested in an instrumented home. The approach involves use of an outdoor reset control which reduces the temperature of the water circulating in the hydronic loop when the outdoor temperature is higher than the design point for the region. Results showed that this strategy allows the boiler to operate in the condensing region for 80% of the winter heating season with oil, 90% with propane, and 95% with gas, based on cumulative degree days. The heating system as tested combines space heating and domestic hot water loads using an indirect, 40 gallon tank with an internal heat exchanger.
Keywords	Boilers Residential buildings Thermal efficiency Heat exchangers Space heating Energy efficiency Hot water Propane Vapor condensation Design Performance
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Brookhaven National Lab., Upton, NY. Dept. of Energy Sciences and Technology.; Department of Energy, Washington, DC. Office of Building Technology.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC. Office of Building Technology.
Document Type	Technical Report
NTIS Issue Number	200518