MOUNTING
AND INSTALLATION
SHOULD
THE AIR CURTAIN BE MOUNTED INSIDE OR OUTSIDE THE DOORWAY?
Generally,
air curtains will operate with equal efficiency, regardless of which side
of the doorway it is mounted on. However, there are certain exceptions,
as follows:
Either side
of the door opening is acceptable when used for insect control or over
refrigerated coolers. Outside installation is required when used over
freezer doors because when mounted inside, the fans tend to gather moisture
and freeze, eventually forming a snowball around the fan, causing it to
lose operational efficiency. Inside installation is mandatory when used
as a thermal barrier in factories, stores, etc., to prevent loss of heat
and keep out the cold air. Heated units for customer entrances and service
windows must always be mounted inside.
DO
MARS AIR CURTAINS REQUIRE A COVER WHEN MOUNTED OUTSIDE?
No,
they are not necessary since their design protects them from inclement
weather. Weatherproof covers are necessary and therefore supplied as standard
equipment. All units are UL listed for outdoor use.
IS
THERE ANY DIFFERENCE IN THE SOUND LEVEL
IF A MARS AIR CURTAIN IS INSTALLED OUTSIDE OR INSIDE?
Yes.
If the level of sound is a problem, mount the air curtain outside and
the sound will be reduced.
HOW
FAR ABOVE THE DOORWAY HEADER SHOULD THE AIR CURTAIN BE MOUNTED?
One
half to two inches above the door opening whenever possible. The closer
to the top of the door opening, the more effective the air curtain will
be. Extended mounting brackets are available in various lengths so the
air curtain can be mounted to clear an obstruction.
IF
THERE IS AN OBSTRUCTION OVER THE DOORWAY, HOW FAR AWAY FROM THE WALL CAN
THE AIR CURTAIN BE INSTALLED AND STILL FUNCTION EFFECTIVELY?
Not
more than eight inches for refrigeration and fourteen inches for insects.
To seal off the ends, twelve to eighteen inch panels made of sheet metal,
plastic strips or plywood can be installed on each side of door opening
to improve the efficiency of the air curtain. Sometimes the Mars air curtain
air outlet nozzle may be installed between the obstruction and the wall.
Precaution is necessary to prevent the obstruction from deflecting the
flow of air.
WHAT
ARE THE NORMAL HEIGHTS THAT AN ELECTRIC HEATED MARS AIR CURTAIN CAN BE
MOUNTED?
Electric
heated air curtains with 1 / 2 HP motors are normally used over customer
entrance doorways in restaurants, supermarkets, department stores, personnel
entrances, etc. and installed no more than 8 feet high above the floor.
The colder the climate the higher the kW heater should be selected. If
specifying electric heated models for use over warehouse doorways, use
either HV or EP models. Higher kWs should be used in this case. All electric
heated models are supplied with motor control panels and wall-mounted
thermostats for On/Off/Fan Only control.
WHEN
MORE THAN ONE AIR CURTAIN IS INSTALLED OVER A DOORWAY, HOW CLOSE TOGETHER
SHOULD THEY BE MOUNTED?
They
should be mounted next to each other, however, if the door opening is
wider than the units, spacing up to six inches between units is acceptable.
W-25 models can be spaced up to three inches apart. For longer pass-thru
openings, use a series of C or Whispurr Air models.
WHAT
HAPPENS IF THE AIR CURTAIN IS MUCH SMALLER THAN THE DOOR-WIDTH OPENING?
Whenever
possible, avoid using an air curtain that is shorter than the entire width
of the door opening. An undersized air curtain will create unprotected
areas on each side, thereby reducing its efficiency level. An air curtain
should cover the doorway completely. If necessary, it’s always better
to use an air curtain that is slightly wider than shorter in covering
the opening.
Some manufacturers will provide their units with extreme side deflectors
to help spread the air outward. Avoid using this type of design. The output
airflow pattern becomes very irregular. Much of the airflow moves across
the opening, causing considerable air velocity loss by the time it hits
the floor.
WHEN
WOULD A VERTICAL MOUNT BE FEASIBLE?
When
installation is not possible over the top of the doorway, the Mars air
curtain may be side-mounted on both ends of the door, blowing into the
center of the door opening. This type of installation must be specified
at time of order. The pan of the motor/fan assembly will be bolted to
the air curtain housing instead of the standard wing nut mount hardware.
All motors used in Mars air curtains contain thrust bearings and operate
efficiently in ay position.
WHERE
ARE THE JUNCTION BOXES?
Each
motor within the air curtain housing will have one watertight junction
box mounted on the bottom center of its motor/fan assembly. If specified
at time of order, the junction box can be located elsewhere.
HOW
DOES THE AIR CURTAIN MOUNT OVER A LARGE WAREHOUSE ROLL-UP DOOR?
Each
unit is sent with installation instructions explaining how to fabricate
brackets for a roll-up door. As an accommodation, the factory can supply
special brackets for a nominal charge.
WHEN
THERE IS A FOYER, WHERE SHOULD THE AIR CURTAIN BE MOUNTED?
To
be most effective, the air curtain should be mounted inside the foyer
over the building entrance door. Depending upon climatic conditions, either
a heated or unheated model may be used.
WHEN
AN AIR CURTAIN IS MOUNTED OVER A COOLER DOORWAY, CAN THE DOOR ITSELF BE
REMOVED AND THE AIR CURTAIN ALLOWED TO OPERATE CONTINUOSLY?
No.
Inasmuch as air curtains provide up to an 80% thermal efficiency level,
the continual loss of refrigerated air and build-up of humidity within
the cooler, will cause the compressor to burnout. They are meant to be
used as an energy saving device when the cooler door needs to be opened
for loading and unloading purposes.
HOW
DO YOU CLEAR EXISTING LINES AND TRACKS OVER A DOORWAY?
Mars
provides a variety of optional mounting hardware accessories. Side extension
plates are available to further extend the outboard mounting holes. These
plates are available in various sizes up to a nine inch extensions for
both ends of the air curtain. Adjustable mounting brackets and extended
wall mount brackets for drum type roll-up doors are also available. These
type of brackets are used when the air curtain needs to be mounted some
distances away from the wall. The brackets are available in various sizes
to provide 2 1 / 2 to 23 inches of clearance. Please consult factory for
details.
HOW
DO YOU MOUNT A MARS AIR CURTAIN OVER A MEAT TRACK THAT COMES OUT THROUGH
THE CENTER OF THE DOOR OPENING?
Sometimes
one unit can be installed over the door opening on top of the track, but
very often there are obstructions and the unit would have to be installed
much too high. Therefore, one unit on each side of the track would be
more efficient because installation is then closer to the top of the door
opening. The air curtain should be mounted three to four inches away from
each side of the track to prevent interference with products being sent
through.
HOW
LONG DOES IT TAKE TO INSTALL A MARS AIR CURTAIN?
The
average time required to install a unit is two hours. After the second
or third installation, the time can usually be cut to one hour.
OPERATION
AND PERFORMANCE
HOW
FAR BEYOND THE EDGE OF THE HOUSING DOES THE AIR SPREAD AND WHAT IS THE
DEPTH?
The
air leaves the discharge nozzle at very high velocities. The air spread
and depth of "air wall" created varies between models. A general rule
of thumb is: for units with 1HP motor(s) or less, the air spread is up
to 3 inches and the depth of the wall of air created is about 18 inches,
measured 6 feet from the nozzle. For units with motor(s) larger than 1HP,
the air spread is up to 6 inches and the depth of the wall of air is about
24 inches, measured 6 feet from the nozzle.
WHAT
COULD THE CAUSE BE IF AIR LEAVING THE NOZZLE DOES NOT SEEM TO HAVE MUCH
VELOCITY?
Possible
causes for low air outlet velocities are:
A. Incorrect
rotation of the fans. This c need to be reversed for correct rotation.
B. If air directional
vanes at air outlet nozzle are turned beyond a definite limit, they
will restrict the air flow.
C. Fan blades
need cleaning.
WHY
DO MARS AIR CURTAINS HAVE ADJUSTABLE LOUVERS AT THE AIR INTAKE?
Adjustable
louvers are used to obtain optimum operating efficiency. When used over
refrigeration doors, the louvers can be adjusted to regulate the velocity
and volume of air at the air outlet. This is important in order to form
an air barrier and balance the cold air inside the refrigerated box with
the warm outside air. The louvers should be set so the air barely hits
the floor. The colder the air, the stronger and stiffer the barrier should
be. When used as a barrier to insects, louvers should be set tat the maximum
open position for full volume of air.
WHEN
ADJUSTABLE VELOCITY CONTROL LOUVERS ARE COMPLETELY CLOSED, WILL THE MOTOR
BE STARVED FOR AIR AND THEREFORE OVERLOAD?
No,
on the contrary, the motor will be working under a lighter load. When
the louvers are closed, there is less air to load the fan blades, thus
allowing them to operate "free wheeling". The amperage draw of the motor
drops significantly.
WHY
DO MARS AIR CURTAINS HAVE ADJUSTABLE AIR DIRECTIONAL VANES AT THE AIR
OUTLET?
The
air directional vanes in the discharge nozzle can be positioned inward
or outward. This design feature provides the capability to compensate
for drafts, wind loads and necessary adjustments to effectively repel
flying insects, dust, fumes, odors and other wind borne contaminants.
If the air curtain is mounted internally in a building for environmental
separation (i.e. separating a manufacturing area from a clean work area)
or over a refrigerated room door for temperature control, the directional
vanes should be pointed straight down.
WHAT
HAPPENS TO THE AIR WHEN IT HITS THE GROUND?
As
the air reaches the floor, it will divide, sending the air inward and
outward simultaneously and causing a draft both ways at the floor line.
When using an air curtain for insect and dust control, the directional
vanes in the air outlet nozzle should be directed outward not only to
repel the insects and dust but to also allow the least amount of air to
come inward when hitting the floor. If mounted on the outside of the doorway
and used for the purpose of holding in air conditioning when the door
is open, the directional vanes should be slanted slightly outward. Mounted
on the inside of a cooler, the vanes should be turned slightly into the
refrigerated room. It is important to remember that when an air curtain
is used for refrigeration or climate control, it is absolutely necessary
to adjust the velocity control so the air stream gently hits the floor
with the least amount of vacuum reaction, thus pulling the air out of
the protected room and defeating the intended function of the air curtain
and causes icing on the floor.
ARE
THERE ANY SITUATIONS THAT COULD CAUSE AIR CURTAINS TO OPERATE POORLY OR
NOT AT ALL?
Yes.
There are three applications to be avoided.
Air curtains will not perform satisfactorily if there is an exhaust fan
in operation causing a negative pressure within the building. The curtain
of air will be strongest near the nozzle and weakest at the floor. Since
air entering the building always seeks the least line of resistance, it
will flow into the building a few feet from the floor at the door opening.
A wind tunnel effect will prevent air curtains from operating properly.
A wind tunnel effect occurs when there are two open doors, one on each
side of the building. If an air curtain is mounted on the outside of a
building and it is not being used to prevent the entrance of cold air,
it will not perform properly. If mounted outside, cold air coming down
will hit the floor, bringing cold air into the building. It must be mounted
on the inside of a heated room.
SHOULD
THE CUSTOMER USE A THERMAL OVERLOAD PROTECTION SWITCH IN THE ELECTRICAL
CIRCUIT?
Not
necessarily. All motors used in Mars air curtains are equipped with an
automatic thermal overload switch in the windings of the motor for protection
against burnout. If for any reason the motor is overheating, the motor
will automatically stop.
Possible causes
for overheating are:
A. Wrong voltage
being fed to the motor. Too low a voltage. Phases unbalanced in
three phase motors.
B. Excessive
vibration in fans caused by debris caught in the vanes.
C. Motor dirty.
Air cannot get to motor housing for proper cooling.
D. Wiring hookup
not properly followed, or the wire is too light a gauge from electrical
panel to air curtain.
ARE
VARIABLE SPEED MOTORS REQUIRED ON AIR CURTAINS?
The
ability to adjust the outlet airflow is highly desirable. It significantly
aids in the air curtain’s performance by allowing compensation for
varying field conditions. All Mars air curtains have this feature. Most
provide it through the adjustable air intake louver, some feature variable
or multi-fixed speed motors; others through internal volume dampers in
the air curtain’s discharge nozzle, and certain models contain a
combination of the above. Please consult factory for specific model offerings.
IF
A WAREHOUSE FOR COMMERCIAL BUILDING IS HEATED, WHAT ARE THE ADVANTAGES
OF INSTALLING AN AIR CURTAIN?
Heat
rises and tens to stratify. The air curtain will cause the air to circulate,
eliminating the stratification. This action helps to reduce heating costs.
The directing of a space heater toward the air curtain intake, if practical,
will assist this action and minimize any cold drafts by bringing the warm
air down to floor level with sufficient velocity and at the same time,
will prevent cold air from entering the building, thus saving on energy.
CAN
AIR CURTAINS BE USED TO HOLD IN EXTREME HEAT INSIDE INDUSTRIAL CONVEYOR
OVENS?
Yes,
as long as the air curtain is mounted on the outside of the oven. The
smaller the opening, the more effective the installation as the percent
of heat loss is held to a minimum.
CAN
A MARS AIR CURTAIN BE OVER A BLAST FREEZER?
Yes.
Use the same models as you would over a regular freezer.
WHAT
TYPE OF MAINTENANCE DOES THE MARS AIR CURTAIN REQUIRE?
All
motors have lifetime lubricated sealed ball bearings, making greasing
or oiling unnecessary. Blowing or wiping dust off the fans and motors
whenever it is visible is advisable to ensure maximum performance.
DO
MARS AIR CURTAINS MEET OSHA REQUIREMENTS?
The
sound level produced by all Mars air curtains is below what OSHA considers
injurious, making approval unnecessary.
ACCESSORIES
AND OPTIONS
WHAT
IS A MICRO SWITCH AND WHEN IS IT USED?
A
micro switch activates the air curtain when a door is opened and turns
it off when the door is closed. The two types of micro switches used with
Mars air curtains are ‘plunger style’ for doors that have
hinges, and ‘roller style’ for all other types (i.e. roll-up,
sliding, vertical lift, track, garage style, etc.). When the door is shut,
the switch’s contacts are held open. When the door is opened, the
contacts are closed, thereby turning the air curtain on. Generally, a
micro switch is installed when a door is intermittently in use, such as
over receiving and cold storage doorways. It is preferable to allow the
air curtain to operate continuously and not to install a micro switch
if there is heavy in and out traffic. When using a micro switch, a motor
control panel is recommended for all three-phase motors and single phase
motors with combined capacities of more than 1HP.
CAN
A MICRO SWITCH BE USED ON ALL TYPES OF DOORS?
Yes.
Plunger styles are used on single- or double-hinged doors that swing one
way either (inward or outward). Roller styles are used on all other types
(i.e. hinged doors that swing inward and outward, sliding, roll-up, return
track, vertical lift, garage style, etc.).
WHAT
IS A MOTOR CONTROL PANEL AND WHEN IS IT USED?
A
motor control panel is an enclosure containing the equipment to start
electric motors, usually mounted on the wall near the air curtain to be
controlled. The equipment consists of motor starters, a transformer for
the control circuit, terminal blocks and other components to meet specific
requirements. It is also used to start, stop and protect the motors in
the air curtains. Motor control panels are available as an option and
can be manufactured to meet any requirement. All electric heated models
contain a motor control panel as standard equipment. All Mars motor control
panels are U.L. Listed.
CAN
FILTERS BE USED IN FRONT OF LOUVERS?
Yes.
Filters can be used in conjunction with or instead of louvers. Filters
are used when there is an excessive amount of dust and dirt in the air.
All Mars NSF Certified models feature a washable aluminum filter as standard.
Filters are also supplied with the W-25 service window model.
WHICH
MARS AIR CURTAINS CONTAIN STAINLESS STEEL BLOWER WHEELS?
The
EP models have stainless steel fans. All other models and all heated models
have galvanized steel fans, except the Whispurr Air models, which are
nylon.
MISCELLANEOUS
DOES
MARS AIR DOORS ADVERTISE NATIONALLY?
Yes,
a heavy advertising program has always been aimed at the user. Our advertising
has appeared in numerous food, beverage, supermarket. Heating and air
conditioning, refrigeration, etc. trade journals. We are also in specialized
publications such as: Sweet’s Catalog, Thomas Register, Architects’
First Source, Arcat and AutoQuotes automated catalog services.
WHAT
ARE THE MAIN ADVANTAGES
OF THE MARS AIR DOORS BRAND AIR CURTAINS?
- All housings are
one piece, as specified by architects. Units are never bolted together
to obtain longer housings. The modular concept of bolting units together
is structurally unsound and aesthetically displeasing. The practice
of bolting unites together to achieve longer lengths, whether patented
or not, is misleading to the user.
- WA, C, CH, CHS,
COMBI, W-25 Service Window models and HEPAC® models have PolyMars housings.
PolyMars housings are advantageous for various climates and décor. Custom
colors are available.
- A variety of over
250 compact models to fit any size doorway in unheated and electric,
gas, steam and hot water-heated models.
- Heavy duty totally
enclosed motors. All other components are of the highest quality to
provide long life and trouble-free service. Two speed motors available
as an option at no additional cost. Three speed 1 / 2 HP motors are
standard equipment on all COMBI models. Three-phase motors in single-speed
only.
- All motors have
one second motor start to full capacity operation.
- Easy to install
and maintain by removing two wing nuts and quickly lifting out the entire
motor/fan assembly. Mars originated this "One Man installation" design.
- Designed to fit
over doorways up to 12 feet wide. Can be used in multiples for wider
openings.
- Motor/fan assemblies
are interchangeable in various models.
- Contain air directional
and velocity controls for find adjustments. This is imperative for climate
control and over refrigeration doorways.
- Five year parts
guarantee on all models except heated and WindGuard models, which have
an eighteen month guarantee. These are the longest guarantees in our
industry.
- Freight paid to
destination or port of embarkation anywhere within the continental United
States (gas-heated and WindGuard models excluded).
- All unheated and
electric heated air curtains are UL Listed. Unheated air curtains are
also C.U.L. Listed and/or Canadian Standards Association Certified.
Gas heated hiar curtains consist of a UL Listed air curtain equipped
with an American Gas Association design-certified duct furnace.
National Sanitation Foundation
(NSF) Certified models available.
Large inventory ensures
immediate delivery.
MADE WITH PRIDE IN THE U.S.A.
SINCE 1962
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