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Retrofitting Forced Air Combi Systems: A Cold Climate Field Assessment

Author(s)
McAlpine Jake,
Bohac Dave,
Schoenbauer Ben,
Hewett Martha,
Rothgeb Stacey
Organization(s)
NorthernSTAR Building America Partnership,
NorthernSTAR,
University of Minnesota,
UMIN
Publication Date
Description

This project analyzed combined condensing water heaters or boilers and hydronic air coils to provide high efficiency domestic hot water (DHW) and forced air space heating. Called "combi" systems, they provided similar space and water heating performance less expensively than installing two condensing appliances. The system's installed costs were cheaper than installing a condensing furnace and either a condensing tankless or condensing storage water heater. However, combi costs must mature and be reduced before they are competitive with a condensing furnace and power vented water heater (energy factor of 0.60).