Measure Guideline: Combination Forced-Air Space and Tankless Domestic Hot Water Heating Systems

This document describes design and application guidance for combination space and tankless domestic hot water heating systems (combination systems) used in residential buildings, based on field evaluation, testing, and industry meetings conducted by Building Science Corporation. As residential building enclosure improvements continue to drive heating loads down, using the same water heatingequipment for both space heating and domestic water heating becomes attractive from an initial cost and space-saving perspective. This topic is applicable to single- and multi-family residential buildings, both new and retrofitted.