PROJECT
hvac
Selecting The Correct Damper There’s more to choosing a thermally efficient damper than R-value. Rachel Larimore, Ruskin
D
epending on the application, thermally efficient dampers can reduce energy costs significantly, compared to standard dampers. Extrap-
olate that over a hundred dampers in a single building, and building owners can realize substantial savings per year versus the use of less-efficient dampers. Thermally efficient dampers are used in air openings of buildings to control and direct airflow. This function ensures proper operation of heating, ventilation, and air-conditioning (HVAC) systems and minimizes potential heat loss to improve overall building efficiency. In application, thermally efficient dampers can allow airflow between interior spaces but are primarily used in exterior outdoor openings. Given the wide range of applications, dampers can be designed to fit in openings as small as 6 x 6 in. or as large as 12 x 12 ft. and beyond using multi-section assemblies. This type of damper can be applied in many different environments, but they are especially useful in extreme hot and cold ambient conditions. Damper models are available for ambient temperatures ranging from –70 F to 200 F. In cold climates, such as Canada for example, thermal-
ly efficient dampers help reduce heating costs. In southwest U.S. locales such as Arizona and California, they can help cut cooling costs. Typical applications vary from large-area freezers in food-storage facilities to warehouses,
Above. In specifying a thermally efficient damper, it’s imperative to evaluate the design of the airfoil blades, the blade seals, and the jamb seals to ensure a high overall damper efficiency rating. Top right. A thermally efficient damper blade requires isolation between the warm and cold sides of a damper even if the blade is insulated. Look for a thermal break placed strategically between twin-blade edge seals. Right. Jamb seals should be made from silicone or similar durable and non-conductive material. Ruskin, for example, uses a proprietary material (Ruskiprene) that protects against condensation and heat transfer better than stainless steel.
laboratories, or any space requiring a steady temperature at all times. Applications can also include data centers,
that a precise amount of air volume is being introduced
damper based on an R-value, the same metric used to
commercial buildings, and industrial or manufacturing
into the system or space.
measure heat transfer through a building material such as insulation.
facilities desiring tight temperature control. Installing thermally efficient dampers typically in-
MEASURING THERMAL PERFORMANCE
R-value is the measure of resistance to conductive heat
volves flange mounting the damper into an outside-air
Precise operation and thermally efficient design is critical
flow through a material, which varies by the material’s
opening. To improve thermal efficiency and lower the
to damper performance, as air leakage is a critical compo-
properties, such as thickness. The higher the R-value, the
heat transfer, all sides of the damper’s extruded aluminum
nent of the thermal-efficiency equation, combined with
better the material’s ability to resist heat transfer.
frame should be thermally broken in two locations. These
heat conduction. In winter, the damper blades need to
R-value ratings are determined by the American Soci-
breaks isolate each interior section, eliminating thermal
form a very tight seal to keep the space warm and prevent
ety for Testing and Materials (ASTM, West Conshohock-
conductivity.
cold air from entering an opening that may be used to ad-
en, PA, astm.org) ASTM C 976-90 Standard Test Method
Attachment to duct work is accomplished through a
mit outside air for ventilation during the summer. Better
for Thermal Performance of Building Assemblies by
T-flange. Other flanges and damper actuators can be in-
leakage prevention is one reason why some non-thermal
Means of a Calibrated Hot Box.
stalled to meet the requirements of different openings.
dampers can outperform insulated thermal dampers that
Various mounting configurations provide the flexibility
are labeled as thermally efficient.
There are two major parts of the damper—the blades and the frame—where heat transfer through the material is of concern and where R-value is relevant. However, due to
needed to fit a wide range of needs. For example, thermally efficient dampers can be used in conjunction with ded-
R-VALUE METHOD
different materials and thicknesses used in damper con-
icated outdoor air systems (DOAS) and air-handling units
There are several methods used to measure damper
struction, R-value is only one aspect to consider in deter-
(AHU) paired with airflow-measuring devices to ensure a
performance. In the past, an engineer might specify a
mining overall thermal efficiency of the damper. In fact,
commercialarchitecturemagazine.com
FEBRUARY 2018
COMMERCI A L A RCHI T EC T URE
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