FORM 100.50-EG3 (802)
For VAV applications, the YORK eco
unit uses a VFD
BUILDING EXHAUST SYSTEMS
to modulate fan speed and maintain a constant duct
static pressure. VFDs offer superior control over the
Building exhaust systems are often necessary when
operation of the unit at part load, and offer the addi-
economizers are used to bring in outdoor air. Without
tional benefits of quieter and more efficient operation
proper building exhaust, the building may become over-
when compared to IGV.
pressurized. The exhaust system maintains the proper
building pressure by expelling the appropriate amount
of air from the building. Exhaust systems are typically
HARSH ENVIRONMENTS – CONDENSER AND
designed to exhaust approximately 10% less air than
EVAPORATOR COIL PROTECTION
what is entering the building. This provides a slight posi-
tive pressure in the building.
For harsh environmental conditions such as seashore
applications, YORK offers three types of coil protec-
100% modulating exhaust with building static
tion: copper fin material, black fin and Technicoat coat-
pressure sensing and control
ings. YORK recommends that for corrosive environ-
The 100% exhaust system can be configured with ei-
ments that copper fins be used to protect the evapora-
ther control actuated dampers or VFDs for modulating
tor and/or condenser coils. In areas where chemicals
control. The unit controller monitors the building pres-
that can corrode copper are present, such as ammo-
sure using a differential pressure transducer and main-
nia, YORK recommends that the black fin or Technicoat
tains the required building static pressure by modulat-
coating be used for maximum protection.
ing the exhaust control. If the building has other means
of exhaust or building pressure is not important, on/off
Copper Fin Condenser Coil
or barometric control may be used.
Copper fins can be used instead of aluminum for addi-
Powered exhaust with fan on/off control
tional corrosion protection, however it is not suitable
for areas that are subject to acid rain or exposed to
The 100% exhaust system can be configured for on/off
operation eliminating the expense of the damper ac-
tuators or VFDs. This exhaust system can be controlled
Pre-Coated Condenser Fins
by either the outside air damper position, or a building
static pressure sensor.
Black fin coating (yellow fin for evaporator fins) is pre-
coated application epoxy on aluminum fin stock to guard
from corrosive agents and insulate against galvanic po-
tential. It is used for mild seashore or industrial loca-
Barometric exhaust can be used when smaller amounts
tions. This can provide corrosion resistance comparable
of air at low static pressure variations within the build-
to copper fin coils in typical seashore locations.
ing or other means of building exhaust are employed.
Barometric exhaust is commonly used where there are
only small fluctuations in building pressure or where
Post-Coated Condenser Fins
building static pressure control is not necessary.
Technicoat (a post-coated application of epoxy) can be
used for seashore and other corrosive applications with
the exception of strong alkaloides, oxidizers, wet bro-
mide, chlorine and fluorine in concentrations greater
YORK offers optional roof curbs designed specifically
than 100 ppm.
for the eco
footprint. These curbs come disassembled
and require field assembly and installation. For bottom
Any of the above suitable options should be selected
supply and return openings, the curbs have matching
based on the particular project design parameters and
connections to ease installation. A pipe chase that
related environmental factors. The application should
matches the rooftop unit pipe chase is also included in
be further reviewed and approved by the consulting en-
the curb footprint for through-the-curb utility connections.
gineer or owner based on their knowledge of the job