Titan Air User Manual
18349
Rohner
360-885-7641
3
24 MONTH WARRANTY
Titan Air hereby warrants its products against defects in material and workmanship for a period
of (24) twenty four months from date of shipment.
Start up checklist is due back within (30) thirty days of start-up or 120 days from date of delivery
for 24 month warranty to be effective. After (30) thirty days, and up until (60) sixty days, a (13)
thirteen month warranty will be observed. All warranties are null and void if start up checklist is not
received within (60) sixty days from start-up or 120 days from date of delivery. NO EXCEPTIONS
WILL BE MADE.
Titan Air reserves the right at Titan Air’s option, to replace or repair free of charge, any part
proven by Titan Air to be defective. Prompt notification of defective part must be given to Titan Air
and defective part must be returned freight prepaid within (30) thirty days of notification.
WARRANTY INCLUDES ONLY PARTS SUPPLIED BY TITAN AIR INCIDENTAL COSTS AND
LABOR CHARGES SHALL BE THE RESPONSIBILITY OF OTHERS. This warranty does not cover
fuses, belts, filters, refrigerant or water damaged parts which are the result of improper storage or
installation.
This warranty is void in event the product is improperly installed and/or operated under
conditions other than normal published ratings, improperly maintained, misused or not in compliance
with applicable codes or not in accordance with Titan Air’s operating instructions.
This warranty is void if attempts to correct or repair any alleged defective part or parts are made
by unauthorized personnel without Titan Air’s written approval.
In no event shall Titan Air be held liable for any damage, incidental or consequential, arising from
the installation, performance or operation of the product.
This warranty supersedes, voids, and/or is in lieu of any other verbal or written understanding
which may not be in total accordance with this expressed warranty.
Warranted parts must be returned to Titan Air within 60 days to receive credit.
Purchased components such as Steam Generators Systems, Electric Coils, Refrigerant
Condensers, Chillers, Coils, Heat Exchangers are covered under the original equipment
manufacturer’s warranty.
4
PURPOSE/ APPLICABILITY
This manual is intended to provide installation, operating and service information on Titan Air’s
TA Series H.O.T.™ (High Outlet Temperature) air make-up units. Other types of equipment
including TAP Series H.O.T. ™ units are covered in other manuals.
A packet of reference materials for a specific unit (tracked by its Serial Number) is generally
included with this Operating and Service Manual. The reference materials include Unit
Specifications, Parts Lists, Gas Train and Burner Specifications, Electrical Schematic, and a
Sequence of Operation. A start up checklist is also included in this packet. Review the reference
materials for a specific unit and note any optional equipment or controls which are not specifically
addressed in this manual prior to attempting start-up or service work.
The information and recommendations contained in this publication are based on general
observation and are not intended to supplant requirements of federal, state or local codes having
jurisdiction. These codes should be reviewed before installation of equipment. All units must be
installed in accordance with national, state or local codes.
It is the responsibility of the purchaser at the time of order, to specify any and all code or
insurance requirements that may dictate the addition of components to the equipment in order to
comply with those requirements.
Only qualified personnel who have experience with the installation and operation of industrial/
commercial direct fired equipment should attempt to service Titan Air equipment..
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GENERAL INFORMATION PAGE #
24 MONTH WARRANTY ........................ 3
PURPOSE/ APPLICABILITY ................... 4
EQUIPMENT ARRIVAL ........................... 6
STORAGE ................................................ 6
COMPONENTS ..................................... 7-9
AIR FLOW SWITCH OPERATION ........ 10
INSTALLATION
PRE-INSTALLATION ....................... 11-12
POSITIONING THE HEATER ................ 12
CLEARANCE ......................................... 12
CURBING (OUTDOOR MOUNTING) .... 13
INSTALLATION SAFETY ...................... 13
GAS PIPING ..................................... 13-14
DUCTWORK ..................................... 14-15
SOUND AND VIBRATION CONTROL .. 15
DISCHARGE TEMP SENSOR BULB
INSTALLATION & WIRING ......................... 15
FIELD WIRING ....................................... 15
UNIT AND ACCESSORY INSTALLATION
UNIT & ACCESSORY SUPPORTING
OPTIONS...................................................... 16
SECTION ASSEMBLY-HORIZONTAL17-18
SECTION ASSEMBLY-VERTICAL .. 19-21
ACCESSORY INSTALLATION ........ 22-23
INTAKE DAMPER MOUNTING ............. 24
DISCHARGE DAMPER MOUNTING ..... 24
VERTICAL DISCHARGE DIFFUSER
MOUNTING .................................................. 25
MAINTENANCE
GENERAL MAINTENANCE .................. 26
FILTERS ................................................ 26
BURNER ................................................ 27
GENERAL V-BELT DRIVE TIPS ...... 28-29
BLOWER BEARINGS ........................... 30
MOTOR BEARINGS .............................. 30
BLOWER WHEEL .................................. 30
FLAME FAIL DIAGNOSTICS ............ 31-32
GENERAL START-UP INFORMATION . 33
VALVE LEAK TEST ............................... 34
SPECIFIC EQUIPMENT DETAILS
................................ pages not numbered
UNIT SPECIFICATION
UNIT DRAWING
SEQUENCE OF OPERATION
PARTS/ LEGEND SHEET
SCHEMATIC
GAS TRAIN / BURNER SPECIFICATION
COIL PERFORMANCE REPORTS (IF
APPLICABLE)
START-UP PROCEDURE
TROUBLESHOOTING (OPTIONAL)
SUPPLEMENTAL MANUALS
DX, CW, HW AND STEAM COIL
INSTALLATION & MAINTENANCE (IF
APPLICABLE)
EVAPORATIVE COOLER (IF APPLICABLE)
Note that operating and service manuals are
occasionally requested prior to production of a
unit. These manuals will be marked “PreProduction Release” on the front cover.
The final copy of the operating and service
manual for a specific unit will be sent with the
unit. Additional copies of the manual for a
specific unit are available.
A detailed unit specification sheet, parts/
legend sheet, schematic, sequence of operation
and start-up procedure are provided in the startup section of each operating and service
manual generated for a specific unit. Selected
vendor cut sheets on components will also be
included.
6
EQUIPMENT ARRIVAL
When the air make-up unit arrives, be sure to inspect for shipping damage. The equipment was
thoroughly inspected before leaving the factory. Also upon receipt check the shipment for items
which shipped loose such as a remote box and remote sensors. Consult the Bill of Lading to identify
the potential shipped loose items. It should be noted that these items may have been placed inside
unit cabinet in multiple locations; however, more often than not, shipped loose items can be found in
the blower section of the unit. Any damaged or missing items should be reported to the transporter
immediately. DO NOT SEND DAMAGED FREIGHT BACK TO TITAN AIR! All claims must be filed
with the transporter. Be sure to take photographs and get the driver’s signature to confirm the
damage. The driver will have a number for you to call to file a claim. Request a written inspection
report from the carrier claims inspector to substantiate any necessary claim. Be sure to open the
unit access doors and inspect for internal damage.
STORAGE
If for some reason you are unable to install the equipment immediately, be sure that the
equipment is protected from the elements. Water damaged parts are not covered by Titan Air’s
warranty. If the equipment is stored for an extended length of time, be sure to completely check the
unit for any internal damage which may have been caused by excessive condensation. Also check
for damage caused by rodents, and be sure to eliminate any dust that may have built up on the
components while the unit was in storage.
LONG TERM STORAGE
Please observe the following precautions if the unit is to be stored for an extended period of
time. (NOTICE: The time elapsed during storage still counts against the warranty period.)
Best place to store the equipment is on a clean level surface, in a dry location
where the temperature can be controlled, if possible.
Isolate equipment from shock and vibration or damage may occur to the
stationary blower bearings.
At least once a month enter the blower vestibule and slowly rotate the blower
wheel about 30 times to redistribute the grease inside the bearings to help
prevent corrosion from occurring.
Reduce belt tension by at least 50% or remove belts completely.
Do not allow coverings to trap moisture against unit casing.
CAREFULLY AND THOROUGHLY READ TITAN AIR’S PRODUCT WARRANTY
Each unit is tested at the factory prior to shipping. Because we are not able to simulate exact
field conditions and sometimes actual conditions are different than what was stated on the order,
you may need to make some adjustments in the field. This is why it is very important that only
qualified personnel start-up and service Titan Air equipment. The start-up checklist (provided in
packet with this manual) must be filled out and returned to Titan Air in order to validate equipment
warranty.
For a fee, Titan Air personnel will travel to the job site, supervise start-up and provide operation
and maintenance training for the equipment.
7
COMPONENTS
BLOWERS
The typical blower(s) used in Titan Air equipment are AMCA rated industrial type forward curve
D.W.D.I. fans. Backward incline, backward airfoil, and plenum/plug fans are used occasionally.
Models TA-109 through TA-136 utilize a single blower while models TA-215 through TA-242 utilize
twin blowers. All blower wheels are mounted on a solid, turned, ground and polished shaft. 9” and
12” blowers are supported with permanently lubricated ball bearings. Larger blowers are supported
by relubricatable pillow block ball bearings.
MOTOR & DRIVE
Rigid base, T-Frame, motors are utilized. The motor is mounted on an adjustable slide base.
Equipment furnished with a supply VFD will typically have a fixed motor sheave. However, some
equipment may still utilize a variable pitch sheave.
DIRECT FIRED HEATING
BURNER OPERATING PRINCIPLES
The direct fired burner is designed to
operate in a cabinet of flowing fresh air. Fuel
gas is fed directly to the burner; kinetic energy
of the airstream furnishes combustion air. It
will function properly at the design velocity and
pressure associated with ventilating systems.
Two speed H.O.T.™ units feature a
damper with actuator and controls to maintain
proper velocity across the burner profile as air
volume changes. Single speed H.O.T.™ units
have slide plates on either side of the burner
to allow manual adjustment of the burner
profile area.
The burner must be installed to fire with,
and parallel to, the air flow. By virtue of velocity impact and suction generated by the diverging
shape of the combustion baffles, air is induced through the air ports into the combustion zone.
Although the air supply to the burner combustion zone is constant, only some of the air is actually
mixing with the gas to produce combustion.
When a very small quantity of gas is admitted to the burner, sufficient mixing takes place in the
low fire slot where combustion takes place. Since the low fire zone is contained within the burner
casting it is effectively shielded from uncontrolled air entry.
As the gas supply is increased the flame progresses into the intermediate fire zone where an
additional supply of air is available. At higher or full capacity, mixing occurs at the larger air ports of
the high fire zone augmented by air flowing over the end of the baffles.
On a reduction of gas supply the reverse sequence takes place, the flame recedes to a location
of lesser air supply until the low fire zone is reached. The burner is suitable for a turndown range of
approximately 30 to 1.
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AIR SUPPLY
The supply fan is typically positioned to draw air across the burner. Air flow across the burner
must be substantially straight (laminar) and velocity must be within the proper range to develop the
desired turndown and capacity.
The direct fired burner is designed to operate in an air make-up heater with all air crossing the
burner taken directly from outdoors. Rare exceptions involve equipment that serves an unoccupied
space.
Total pressure rating of the blower includes allowance for the pressure drop through the primary
air handling unit including the burner, together with pressure losses at the inlet screen, inlet damper,
filters, outlet damper if used, plus the external pressure rating of the system.
BURNERS
Burners are purchased in 6” and 12” straight lengths and 12” tee sections and are assembled
to meet the BTU requirements of each piece of equipment.
According to national safety standards, the following factors could influence safe operation of
a direct fired air make-up unit and must be interlocked to either prevent the burner from firing or shut
it down if unsafe conditions occur.
1. AIR SOURCE – If a damper is used, it must be interlocked to prove it is open before the
blower can start.
2. BLOWER STARTER/VFD INTERLOCK – A contact proving that the blower starter is
energized or VFD is operating must be incorporated to prevent burner operation when
the blower is not operating.
3. AIR FLOW SWITCHES – Monitor the air flow (pressure drop) across the burner. The
switches (one high differential and one low differential) will not allow burner to operate if
air pressure drop across burner is outside of the high and low set points.
4. HIGH TEMPERATURE LIMIT – A manual reset high temperature limit control must be
utilized to prevent high temperature situations caused by excessive fuel pressure or lack
of air flow.
5. FLAME SAFEGUARD – Monitors the combustion process during ignition and operation
for safe conditions.
6. HIGH GAS PRESSURE SWITCH – Monitors gas pressure to the burner. This deenergizes the burner in the event gas pressure increases above its set point.
GAS CONTROLS
Titan Air H.O.T.™ equipment is constructed to meet ANSI Z83.25/CSA 3.19 standards.
Components in the gas delivery manifold on standard equipment include: two manual shut-off
valves, gas pressure regulator, two safety shut-off valves and an electronic gas modulating valve.
The pilot control includes a shutoff valve, gas pressure regulator and a pilot solenoid.
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ELECTRIC /ELECTRONIC CONTROLS
Titan Air H.O.T.™ units typically come standard with the following items: disconnect switch,
starter and overload assembly(s) or variable frequency drive(s), control power transformer (if a 3
wire system), air proving switches, high temperature limit, electronic flame safeguard and electronic
flame modulation with remote setpoint adjustment. Control systems can be designed to meet
specific requirements. Numerous temperature controls are available. Since H.O.T. units usually
temper outside air to replace the air exhausted from a paint booth, modulating discharge
temperature control is typical. At least one additional setpoint is usually included for the high outlet
temperature mode.
H.O.T.™ units are typically supplied with a remote control panel. This panel will include
switching for blower & burner operation and temperature setpoint(s). Timers are often included to
automate the bake cycle. Other options common for H.O.T.™ units include controls to interlock with
paint booth lights and compressed air solenoid as well as control a paint booth exhaust fan. Some
units feature operating lights, discharge temperature display, custom controls or contacts by others
to enable blower and/or burner operation.
Refer to the unit specification sheets, parts list, schematic, sequence of operation and start-up
procedure for a specific unit to determine the control options included.
IMPORTANT: If the malfunction of the heater creates a hazard to other fuel burning
equipment in the served building (i.e. supplying make-up air to boiler room) it is to be
interlocked to open an inlet air damper in case of failure.
NOTICE: The operating temperature control system must limit the discharge air
temperature from exceeding 250°F in the process air heater mode and 160°F
ventilation air heater mode.
10
AIR FLOW SWITCH OPERATION
BURNER PROFILE AIR PRESSURE DROP
ANSI standards, Z83.25/CSA 3.19, require manufacturers to monitor air moving across the
burner for both high and low conditions. Titan Air utilizes air pressure drop across the burner to
satisfy this requirement.
Certification testing demonstrated that the burner will function properly between a low pressure
drop of 0.2" w.c. and high pressure drop of 0.95" w.c. The standards also mandate that the switches
cannot be adjustable. This makes air pressure drop across the burner profile a very important factor
at initial start up.
The design burner pressure drop at standard air conditions is 0.60” w.c. and will change as the
temperature of outside air increases or decreases from 70°F. In order for the burner to operate
within the range of the air flow monitoring switch set points, the pressure drop should be as close to
0.60” w.c. as possible.
Air pressure drop across the burner profile is dependent on OA temperature. When the burner is
off, pressure drop will climb significantly during cold weather. The burner is always off on initial start
-up. Therefore, if the burner profile air pressure drop is above 0.70” w.c. during a warm weather
start-up, it may exceed 0.95” w.c. during a cold weather start-up in northern regions. Such a high air
pressure drop would open the high airflow switch and prevent burner ignition.
The following chart will aid in equipment set up at outside air temperatures different from 70°F
when the unit is operating with the burner off. The chart gives pressure drops, at various
temperatures, equivalent to 0.60” w.c. at 70°F.
Note that two speed H.O.T. units feature controls to maintain pressure drop across the burner as
air volume changes. Either high speed and low speed mechanical adjustments of damper actuator
travel or a dual pressure switch assembly are used to control burner air pressure drop. Burner
profile air pressure drop should be measured on high speed with the burner profile dampers near the
full open position. If the burner profile dampers open less than 50% on high speed, the unit is
probably delivering less than full rated airflow.
Burner Profile Air Pressure Drop at Various OA Temperatures (Burner Off)
OA
Temp
(˚F)
Burner
Profile Drop
(w.c.)
OA
Temp
(˚F)
Burner
Profile Drop
(w.c.)
OA
Temp
(˚F)
Burner
Profile Drop
(w.c.)
-40 0.76 10 0.68 60 0.61
-35 0.75 15 0.67 65 0.61
-30 0.74 20 0.66 70 0.60
-25 0.73 25 0.66 75 0.59
-20 0.72 30 0.65 80 0.59
-15 0.71 35 0.64 85 0.58
-10 0.71 40 0.64 90 0.58
-5 0.70 45 0.63 95 0.57
0 0.69 50 0.62 100 0.57
5 0.68 55 0.62 105
0.56
11
PRE-INSTALLATION
Inspect the equipment making sure all parts and accessories are on the job site. Check
equipment against order and packing list. If the equipment has been sitting in storage for some
time, inspect it for moisture (from condensation, rain or snow) and/or dust accumulation. Both can
cause damage to electrical and electronic components as well as bearings and insulation.
INSTALLATION CODES
Care taken during the installation and start-up is vital to the longevity and reliability of the
equipment. Confirm that gas and electric utilities match the rating on the equipment name plate.
This heater shall be installed in accordance with local codes or, in the absence of
local code, according to National Fuel Gas Code, ANSI Z223.1/ NFPA 54, or the
CAN/ CSA B149.1 Natural Gas and Propane Installation Code.
If the heater is to be installed in an aircraft hangar, refer to ANSI/NFPA 409.
If the heater is to be installed in a parking garage, refer to ANSI/NFPA 88A.
If the heater is to be installed in a repair garage, refer to ANSI/NFPA 30A.
For installations in Canada, refer to CAN/CSA B149.1 National Gas and Propane
Installation Codes.
INSTALLATION PREREQUISITES
The heater inlet shall be located in accordance with the applicable building or
mechanical code provisions for ventilation air.
Adequate exhaust and/or relief must be provided to prevent over pressurizing the
served space when the heater is operating at its rated capacity. It should be noted
that this can be accomplished by taking into account, through standard
engineering methods, the structure’s designed infiltration rate; by providing
properly sized relief openings; or by interlocking a powered exhaust system; or by
a combination of these methods.
Heaters installed with intake ductwork must purge at least four air changes the
volume of the intake ductwork prior to an ignition attempt.
Ventilation air to the heater shall be ducted directly from outdoors when heater is
operated in the ventilation air mode.
An electric disconnect switch having adequate ampacity (see name plate on the
heater for voltage and ampacity), if not provided as part of the heater shall be
installed in accordance with the National Electric Code, ANSI/ NFPA 70.
If in doubt regarding the application of the direct fired heater, contact the sales
representative or the factory.
PAINT BOOTH HEATER INSTALLATION PREREQUISITES
Access opening(s) to the heated space must be equipped with door interlock
switch(es) to prevent the operation of the heater during a bake cycle when an
access door is open.
It is recommended to post the following warning marking at each access opening.
“Do not enter this space until the cool down cycle is complete.”
A post purge timer to purge contaminants from the space and cool the products to
avoid a burn hazard must be provided following a bake/ drying cycle.
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PAINT BOOTH HEATER INSTALLATION PREREQUISITES Contd.
An interlock must be provided to:
Lock out paint spraying equipment unless process heater is operating in
ventilation mode.
Lock out facility lighting with-in the heated space during bake cycle.
Ensure equipment has been operated in the ventilation mode for three
minutes or a minimum of four air changes of the paint booth volume,
whichever is greater at the start of the bake or drying cycle.
Initiate the heater fan in conjunction with the operation of the exhaust fan.
POSITIONING THE HEATER
Locate the heater exactly level, making certain minimum clearance required by local codes is
maintained between the heater and any combustible materials. See name plate on unit for minimum
recommended clearances.
When the makeup air equipment is located on a roof or at ground level on a concrete pad, the
unit intake needs to be a minimum of 24” above the roof and/ or ground to prevent the intake of
snow or splashed rain. The unit should be located in such a way to prevent prevailing winds from
blowing directly into the unit intake. If the application is critical, provisions must be made to protect
the unit inlet from the driving winds.
CLEARANCE
Select the installation location and support system (curb, stand or other) that meets or exceeds
all of the minimum safety clearance requirements.
BOTTOM
Unit should be installed to allow clearance for proper condensate trap (If applicable). Do not
install unit on combustible surfaces.
SIDES
The minimum recommended clearance on all sides of the unit except for the service side and
bottom is 6 inches.
SERVICE
The service side should have a minimum of 24 inches of clearance; however it is recommended
that the clearance be at least the width of the widest door.
Also, if the unit includes any coils or has twin blowers more clearance should be provided for
removal of those components.
The minimum clearances listed above are set, in place, by the standard in which Titan Air builds
their equipment to meet; however, one should consult with all authorities having jurisdiction to
ensure they don’t require larger clearances. Furthermore, the unit must be installed in such a way to
facilitate smooth operation and maintenance of all built in sections and components. Also, it should
be noted that the coil pull could be located on either side of the unit. Review the unit submittal
drawing for the correct direction of the coil pull.
13
CURBING (OUTDOOR MOUNTING)
The use of a full perimeter curb or mounting rails under the heater is recommended. The only
openings in the roof should be for the supply air duct, return air duct (if required), gas and electrical
connections (if applicable). These openings must be sealed properly after installation. Titan Air
ships all curbs unassembled and un-insulated. Installing contractor supplies gaskets, cant strips,
insulation, etc.
INSTALLATION SAFETY
RIGGING
DANGER: Never enlarge lifting lug hole to accommodate larger anchor shackle.
WARNING: Never assemble unit sections or sub-assemblies together before rigging.
Always rig unit the way it was shipped from the factory.
CAUTION: It is the installer’s responsibility to confirm that the lifting equipment
capacity exceeds unit weight by an adequate safety factor. Never stack inlet hoods or
other components onto the unit as the unit is being lifted.
IMPORTANT: Apply appropriate sealant to roof curb and duct adapter(s) prior to
setting the unit in place (If applicable).
Lifting Requirements:
Protect coil connections, extending through unit casing, from damage by the
rigging cables through the use of plywood or other suitable materials.
Exercise care when moving the unit.
Rig the unit using ALL the lifting points, in a fashion that holds it level and
prevents it from tipping, falling and/ or twisting.
Spreader bars of sufficient width MUST be used across the top of the unit, to
ensure that the lifting cables clear unit cabinetry.
Utilize the same rigging and lifting methods as the ones applied to the unit, for
lifting the accessories.
Remove all wooden shipping blocks before setting unit(s) onto curb (If applicable).
After sections are set in place, assemble according to Unit Section Assembly (If
applicable).
NOTICE: Warranty does not cover damage from the unit being severely
twisted or dropped during handling.
GAS PIPING
Gas piping must be sized and installed in accordance with applicable codes. It must be able to
deliver the specified CFH and gas pressure at full flow. Refer to unit nameplate or unit specification
sheets for specified CFH and gas pressure.
NOTICE: A manual emergency fuel shut off valve is required to be installed in a
location which is accessible to personnel in case of a fire or explosion at the
equipment. This is the responsibility of the installing contractor.
Care must be taken with the gas piping to prevent problems at start-up and later during
operation. Before the union between the supply line and the unit is connected, the supply line
should be cleaned out to remove any foreign material (dirt, rust, metal shavings, etc.) and a drip leg
should be utilized.
14
GAS PIPING Contd.
Refer to unit nameplate to determine the minimum gas supply pressure required to attain the
maximum specified gas capacity.
Suitable gas controls, regulators and valves (equipped with a diaphragm) in this unit are
furnished with an ANSI approved add-on vent limiter or have an integral vent limiter, if available.
However, final vent limiter approval will always be up to state, city or local codes. If local code
requires these components to be vented to outside, it is the responsibility of the installing contractor.
CAUTION: The heater and its individual shut off valve must be disconnected from the
gas supply piping system during any pressure testing in excess of ½ PSIG.
CAUTION: The heater must be isolated from the gas supply piping system by closing
its individual shut off valve during any pressure testing of the supply system at
pressures equal to or less the ½ PSIG.
During start-up, the technician should perform a gas leak check on all components and piping during
the heater’s normal operation. (See page 34)
DUCTWORK
Ductwork must be sized and installed in accordance with applicable codes and standards. As a
recommendation follow SMACNA guides for proper ductwork design, size and installation. A size
variation may exist from recommended duct size to unit or accessory flange size. Accessories on
the unit intake or discharge may be larger than the openings on the unit. Be sure to check the unit
submittal drawing for the correct equipment connection size. Recommended duct size applies to the
size of the duct at the connection to the equipment. Factory also recommends 2 1/2 times the
equivalent duct diameters of straight ductwork off the discharge outlet of the blower. A properly
designed duct transition from the blower outlet to a larger duct is recommended for long ducts or
ducts with numerous elbows. The unit was designed for a specific CFM and ESP (External Static
Pressure) stated on unit rating plate. The ductwork attached to the unit will significantly affect its
performance.
NOTICE: When the heater is operated as a process air heater with airborne
particulate matter in a recirculation mode, filters must be installed in the return air
duct. The particulate removal filters shall be approved by the authority having
jurisdiction. The return air duct system must also have doors/ access panels for
inspection and cleaning. The filters and duct require periodic inspection and cleaning.
NOTICE: The duct to a process air heater which will allow recirculation must be
designed to prevent recirculation of insufficiently diluted products of combustion. A
minimum amount of ventilation air must be supplied to exceed 200 CFM per 1000
CFH of natural gas based on maximum capacity of the heater plus an allowance to
sufficiently dilute the VOC’s created by the process to maintain the lower explosive
level (LEL) below a 25 percent threshold value.
On heaters mounted outdoors, discharge ductwork should be insulated to minimize
condensation during the “off” cycle in cold weather. A fresh air intake hood with bird screen is
required. Discharge ductwork on a twin blower unit must be common to both blowers.
On a heater mounted indoors with through the roof intake, a “mushroom” type intake hood is
recommended to prevent moisture entrainment. When using “through the wall” intake duct, the
intake louver should have adequate moisture baffling characteristics. All intake ductwork exposed to
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