The existing boiler piping arrangement limits the temperature reset of the hot water heating to above 140°F, in order to protect the boiler from damaging flue gas condensation.
It is recommended that the boiler piping arrangement be changed to a true primary / secondary loop. This will allow the secondary (building distribution) loop to be reset below 140ºF while keeping the boiler water temperature above 140ºF. With this strategy, the building will not be overheated in low heating load conditions.
Issues and Concerns
This recommendation is in accordance with Section 6.3 Heating, Ventilation and Air-Conditioning Systems of the ASHRAE Standard on Energy Conservation in Existing Buildings. ASHRAE Standard ANSI/ASHRAE/IESNA 100-1995 – Energy Conservation in Existing Buildings is an approved standard of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., the Illuminating Engineering Society of North America and the American National Standards Institute.
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