Choosing Heating and Cooling Systems 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 1 of 23
Ducted Systems vs. Radiant Systems Radiant hot water systems use boilers - Ducted systems can use boilers or furnaces for heat Radiant systems can distribute heat through baseboard fin-tubes, radiant panels or radiators, or floors - Ducted systems can move conditioned air through ductwork located within the conditioned enclosure Ducted systems allow for conditioned air to be continually mixed for more homogeneous interior temperatures and accommodate outside air change, filtration, and dehumidification of air -this can be good Ducted systems provide the opportunity for unbalanced airflows - this can be bad 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 2 of 23
Ducted Systems Things to Avoid Air handlers or ducts in vented (to the outside) spaces - why? Building cavities used as ducts - why? Air handlers or return ducts in garage - why? 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 3 of 23
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Mechanical System Interactions that Lead to Moisture Problems 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 5 of 23
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Building Enclosure - Mechanical System Buildings are hollow and more interconnected with complex air distribution systems that leak. Building mechanical systems inadvertently connect the building enclosure to the breathing zone of the occupant. The building enclosure is the pollutant. The HVAC system is the pollutant interstate. Interaction 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 9 of 23
Efficient Distribution of Pollutants The enclosure is now the pollutant And ducts in the enclosure efficiently distribute the pollutant 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 10 of 23
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Panned Floor Joist or Stud Cavity Returns 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 14 of 23
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Mechanical Systems Top Ten Improvements 1. Fan powered exhaust and general ventilation 2. Sealed-combustion/fan powered combustion device exhaust 3. Use MERV 11 or better filters 4. Seal ducts with mastic (<5%) 5. Size heating and cooling equipment using Manual J 6. External duct insulation 7. Pressure balance distribution 8. Provide access for inspecting and cleaning coils and ductwork down stream of coils 9. Locate air handlers in conditioned space 10. Dehumidification during part-load and in damp spaces 2005 Building Science Corporation PR-0510d: BuildBoston 2005 Choosing Heathing and Cooling Systems Page 23 of 23