ashrae 2010 - ra design for ufad
DESCRIPTION
POresented variables associated with the design and construction of return air plenums for UFAD systemsTRANSCRIPT
ASHRAE InsideBuilding Sustainability from the Inside Out
Return Air Design for Under Floor AirASHRAE Winter Meeting
January 2010
James E. Megerson, PE- Vice President
ASHRAE InsideBuilding Sustainability from the Inside Out
Supply Air Plenum
MaterialsPoints of InjectionSealingOperating Pressure
50’
50’
ASHRAE InsideBuilding Sustainability from the Inside Out
Objectives
Return Air Basics for UFADPressure drop / sizingLocationBalancing
Effect on space comfortCase Studies
Effect on Thermal Decay (theorized)
ASHRAE InsideBuilding Sustainability from the Inside Out
Supply operating pressure
ASHRAE InsideBuilding Sustainability from the Inside Out
Energy in = Energy out
<0.05” SP
0.05” SP
ASHRAE InsideBuilding Sustainability from the Inside Out
Return Pressure Drop
Egg Crate ReturnTypical static pressure
ASHRAE InsideBuilding Sustainability from the Inside Out
OVH Return Grille Location
T
T
T
ASHRAE InsideBuilding Sustainability from the Inside Out
UFAD Return Grille Location
T
T
T
Conventional Wisdom
ASHRAE InsideBuilding Sustainability from the Inside Out
UFAD Return Grille Location
T
Conventional Wisdom
ASHRAE InsideBuilding Sustainability from the Inside Out
Shorten Perimeter
TS
ASHRAE InsideBuilding Sustainability from the Inside Out
Optimum Location
TS
ASHRAE InsideBuilding Sustainability from the Inside Out
Common Example
LayoutPerimeter heating/ cooling plenum w/FPBInterior manual supply diffusersInterior return grilles
SymptomsCooler interiorsReturn air temp lower than space tempWarmer than desired perimeter zones
ASHRAE InsideBuilding Sustainability from the Inside Out
Common Example
SolutionRemove extra interior manual diffusersRelocate interior returns to exterior zonesRelocate T-stats
ASHRAE InsideBuilding Sustainability from the Inside Out
Return Air Video – Test 1
ASHRAE InsideBuilding Sustainability from the Inside Out
Return Air Video – Test 2
ASHRAE InsideBuilding Sustainability from the Inside Out
Return Air With No Ceiling
0.12” OD
0.06” SP0.01” OD
0.03” SP
0.01” SP
ASHRAE InsideBuilding Sustainability from the Inside Out
Thermal Decay
Exterior wall / slab interface
ASHRAE InsideBuilding Sustainability from the Inside Out
Thermal Decay
Exterior wall / slab interface
ASHRAE InsideBuilding Sustainability from the Inside Out
Return Air & Thermal Decay
T
How to catch Thermal Decay
78-80°F
78-80°F
ASHRAE InsideBuilding Sustainability from the Inside Out
Thank youQuestions?