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The following is a cause and correction list for common concerns with the damper
Problem
Damper attempts to move but,
does not open fully
High noise level
Excessive leakage across damper
Excessive leakage through
damper frame
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As a result of our commitment to continuous improvement, Greenheck reserves the right to change specifications without
notice.
Specific Greenheck product warranties can be located on greenheck.com within the product area tabs and listed in the
Library under Warranties.
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Phone: (715) 359-6171 • Fax: (715) 355-2399 • E-mail: gfcinfo@greenheck.com • Website: www.greenheck.com
• HTD Series Rev. 3 July 2020
Possible Cause
Actuator sizing incorrect
(excessive torque required)
Obstruction in damper linkage or inside
duct
Modulating control not going full span
Actuator linkage incorrectly adjusted
Damper with jamb seals installed with
blades vertical
Damper linkage modified in the field
Linkage pivots failed
Very high velocity/flow
No seals on dampers
Damper not closing fully
Damper not closing fully
Damper not equipped with blade and
jamb seals
Blade edge seals failed
Stop angles not contacting blade edges
Caulking failed
No axle seals specified
O-ring axle seals worn
Double gland packing not tight
Double gland packing worn
Solution
Verify that correct operating pressures, velocities,
and temperatures were given to manufacturer for
actuator sizing. Replace actuator if necessary.
Inspect for projecting mounting bolts, debris inside
damper and remove.
Verify control signal span from controller
Power actuator, independently if necessary, to verify
that is moving full stroke. Adjust actuator drive
linkage or replace coupling spider if necessary.
Consult factory, for modifications if vertical blade
orientation not specified on damper with seals.
Readjust linkage so blade rotates fully open and
closed.
Replace linkage bars, clevises and pins as required.
Reduce flow through damper.
Retrofit with blade edge and jamb seals.
Readjust actuator or drive linkage to fully close
damper.
Readjust actuator or drive linkage to fully close
damper.
Retrofit with blade edge and jamb seals.
Replace blade edge seals.
Close damper. Loosen fasteners and adjust stop
angles so as to contact blade edge/blade seals.
Recaulk gaps with silicone sealant as required.
Contact manufacturer for available modifications.
Replace o-rings as required.
Tighten adjustment nuts on double gland stuffing
box.
Replace packing as required.
Copyright 2020 © Greenheck Fan Corporation
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