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 Lennox LF24 Series Features
• Direct-to-flame Ignition
• Tubular Heat Exchanger
• Induced Draft Fan
•“Inshot” Burners
• Sidewall Venting
• Directional Louvers
• Insulated Powder Coated Cabinet
• LED Diagnostic Lights
• Legendary Technical Support
Options
• Durable tubular heat exchanger/ Stainless Steel
or Aluminized
• TrueLeaf’s lost cost “bolt-on” Combustion Air Separator
(CAS)
• Complete kits include Gas Regulator and Vent Kits
Necessary Evil or Asset to your operation?
We asked growers for their opinions on the quality of
greenhouse unit heaters available today. Resoundingly,
they agreed their level of satisfaction was very low.
So low, that many growers see unit heaters as a “necessary
evil”; equipment they begrudgingly replace year
after year after year.
Behind these long standing problems are the fact that
for many years the design of greenhouse unit heaters
did not advance. This simply does not make any sense
in view of the fact that essentially all of the other
tools for plant production like glazings, benches, irrigation,
etc. have continued to evolve.
Building on TrueLeaf’s expertise in heating greenhouses
and Lennox’s expertise in building heating equipment,
a new option is now available that will change the way
you look at unit heaters. Lennox Industries has so much
confidence in this product that they back it with a warranty
on its heat exchanger of 15 years on stainless steel
units and 10 years on aluminized steel units*
 Cost Comparisons
Other greenhouse unit heaters available today are designed
with the old “clamshell” style heat exchanger,
positioned above “ribbon” type burners. These
are the most common points of failure, especially in the
greenhouse environment. Heat exchangers invariably fail
at the points where manufacturing processes have weakened
the metal by stamping, crimping and welding. The LF24’s
heat exchanger has no stress points, no points where the
metal has been compromised. Lennox engineers took a huge
step forward by developing the seamless tubular heat exchanger.
Smooth, continuous tubes are formed in a serpentine shape
and then placed in parallel rows. Both ends are carefully
expanded (without metal damage or fatigue) into flat metal
plates that support the heat exchanger tubes and provide
mounting locations for the gas train and burners (at the
bottom end) and flue collector box and power venter (at
the top end).
The design of the LF24 heat exchanger is simplicity
defined. But, make no mistake, a tremendous amount
of development work and rigorous testing is in the
soul
of every unit. Whether you select the aluminized steel or stainless steel option,
you are assured long term, quiet operation.
 Advanced Burner Design
The LF24’s burner design is more akin to that of
a fire-tube boiler than a unit heater. With these “in-shot”
burners, the flame is retained inside the heat exchanger
and fires down the inside of the heat exchanger tube.
This design accomplishes three things: First, it eliminates
the need for separate conventional “ribbon-style”
burners; second, it enhances flame quality and heat transfer;
and third, it eliminates most burner corrosion problems.
Conventional burners fail when moisture from condensation
drips on them. This problem is eliminated with the LF24.
Direct Ignition
The other problem area we discovered with traditional
greenhouse unit heaters is that most spark ignition systems
have proven to be problematic. Many growers have decided
to trade the potential energy savings they offer for the
simplicity and reliability of standing pilot systems.
Lennox believes that standing pilots are a thing of the
past... but also that conventional spark ignition systems
have not lived up to their promises. This is because conventional
spark ignition systems were developed “on top”
of the conventional standing pilot concept.
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Why a Combustion Air
Separator (CAS)?
A TrueLeaf Exclusive! |
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A typical 30’ x 96’ greenhouse
has about 36,000 cubic feet of air. A typical 250,000 BTU unit heater exhausts
@ 3,600 cubic feet of
air and exhaust per hour. For every hour the heater runs, there is a 10%
forced air exchange which means 10% of the heated air is exhausted.
This is expensive and wasteful!
CAS stops this inherent air exchange
by bringing the air needed for combustion in from the outside through
a sealed duct. This means you
are heating only the re-circulated greenhouse air. Thereby increasing
efficiency by 5% to 7% by allowing cooler,drier, cleaner air to be used
in the combustion process, and extending the life of the Lennox unit
heater.
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The innovators at Lennox integrated a “direct-spark” ignition
system into the LF24 that lights the burners directly,
without using any separate pilot light at all.
Direct ignition is the most durable intermittent system
available. And since there is no pilot light to collect
dust and cobwebs, reliability is ensured. Upon a call
for heat from your thermostat, a simple electronic arc
is made next to one of the burners. This burner lights
and ignites the rest of the burners across the unit.
A small flame sensor is placed at the far burner to
verify that all burners are safely lit.
Induced Draft with Horizontal Sidewall Venting
To ensure that your precious fuel dollars remain inside your greenhouse and
don’t end up going out the stack between heating cycles, the LF24 is
equipped with a high quality blower to eject the products of combustion cleanly
and completely. The blower features a stainless steel shaft and bearings.
Horizontal venting increases the seasonal efficiency of the LF24 by reducing
gravitational stack losses of heated greenhouse air. The small cost difference
between the LF24 and conventional gravity stack units will typically
be recovered in 12 months or less.
When your LF24 units are called upon to bring heat
into your greenhouse, the induced draft fan will cycle
on for approximately 30 seconds to “prepurge” any
unburned gasses and to create the proper pressure for
operating the in-shot burners. This fan operates at all
times when the unit is running and will turn off
after the desired greenhouse temperature is reached and
the gas valve is closed.
Direct Drive Fan(s)
All LF24 heaters are equipped with an efficient, quiet,
direct-drive fan. On sizes 250 to 400, two fans are used
for even air distribution over the heat exchanger. Adjustable
louvers allow for precise control of air flow.
The free flowing design of the heat exchanger and
efficient fan provide very high CFM rates and much higher
effective throw distance than the nearest competitor.
This means you will have better air flow and greenhouse
temperature evenness with LF24 unit heaters inside your
operation. Some growers have called this “Soft
Heat”.
Rugged Lightweight Cabinet
Baked on “powder-coated” paint and heavy
gauge steel are the reasons that your LF24 units will
maintain their external appearance for many years. Inside,
insulation has been
installed to keep the surface cool.
Two point cabinet suspension on the 50 to 150 models
and four point suspension on the 200 to 400 models make
overhead installation in your greenhouse easy and secure.
Each suspension point features 3/8” “spotnut” attachments.
Special hanging kits can be purchased separately.
LED Diagnostic Lights
Diagnostic lights provide a visual
indication of potential operating issues. A flashing
pattern reports five different
early warnings for growers to diagnose greenhouse heater
problems comprehensively.
 TrueLeaf
Multi-Duct Greenhouse Heating System
Designed primarily for “row crop” production
of vegetables, and cut flowers, where hot air and dehumidification
are well suited. A traditional Lennox LF24 series greenhouse
unit heater is mated with a blower style fan engineered
to provide optimum CFM and static pressure.
A duct system transports the airflow across the end
of the greenhouse and poly tubes are “teed” off
that duct to distribute heat down each row. A locking
damper control ensures a balanced distribution of air.
This system is especially suited for production of greenhouse
tomatoes, peppers and cucumbers.
 Hot Shot Models
Available in 30,000, 45,000, 60,000 and 75,000 BTUH
models. Great for use in cold frames, hobby house, garden
sheds or head houses. Anywhere that you need a little “Hot
Shot” of
heat.
Gas Pressure Regulator
TrueLeaf can provide the correct gas pressure regulator
for each model Lennox, natural gas or LP. The regulator
is an essential element if the gas service at the location
of the unit is delivered at higher than 14” WC
(1/2 PSI).
Stainless Steel upgrade
Heaters come standard with an aluminized heat exchanger,
with a 10-year warranty. The upgrade to stainless steel
is a good choice for the greenhouse industry; the upgrade
offers a 15-year warranty.
LP Conversion Kit
All Lennox units come equipped for natural gas. LP
fuel conversion kits are available and must be added
to your order. This option will be shipped separately
and must be installed on site.
Polytube Adapter
We build these adapters to connect perforated polytube
to the outlet of LF24 units. You can inflate up to 150
foot length with twin fan units (LF24250 and up).
Venting
TrueLeaf has packaged the correct venting materials for
each model Lennox. Exhaust venting is essential to make
the unit heater function properly. Venting is pre-packaged
and ready to ship as a convenient option for you. Includes
single wall vent pipe, type-B vent pipe, elbows, fire
stop and the all important bird screen cap. Inlet venting
is only required if you choose to add a Combustion Air
Separator Kit (CAS).
Combustion Air Separator—CAS
• Available exclusively with TrueLeaf / Lennox unit
heaters.
• Easily installed with 6 bolts
• Very cost-effective pricing (Compare to Modine® “PSH” series)
LF24 Hot Shots
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LF24-30A
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LF24-45A
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LF24-60A
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LF24-75A
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Heating Capacity
Input Btuh (kw) |
30,000 (8.8) |
45,000 (13.2) |
60,000 (17.6) |
75,000 (22.0) |
Heating Capacity
Output Btuh (kw) |
24,300 (7.1) |
36,500 (10.7) |
48,000 (14.1) |
60,000 (17.6) |
| Steady State Efficiency |
81.00% |
81.00% |
80.00% |
80.00% |
| Air Volume-cfm (L/s) |
535 (250) |
750 (355) |
830 (390) |
950 (450) |
| Temp. Rise-°F (°C) |
42 (23) |
45 (25) |
55 (31) |
60 (33) |
| Air Throw at 8ft. (2.4m) Mounting Height-ft. (m) |
25 (7.6) |
25 (7.6) |
40 (12.2) |
40 (12.2) |
| Flue Size Vertical Venting |
3 (76)* |
3 (76)* |
4 (102)** |
4 (102)** |
| Round in.(mm) Horiz. Venting-Residential |
4 (102)*** |
4 (102)*** |
5 (127)**** |
5 (127)**** |
| Gas Piping Size-in.(mm) Natural
or LPG Propane |
1/2 (13) |
1/2 (13) |
1/2 (13) |
1/2 (13) |
| Amps |
1.7 |
1.7 |
4.1 |
4.1 |
| Fan Motor RPM |
1650 |
1650 |
1050 |
1050 |
| Electrical Characteristics |
115 V-60 Hz-1 phase |
115 V-60 Hz-1 phase |
115 V-60 Hz-1 phase |
115 V-60 Hz-1 phase |
| Shipping Weight- lbs.(kg)1 pkg. |
60 (27) |
63 (29) |
87 (40) |
91 (41) |
| Width (Inches) |
25 |
25 |
25 |
25 |
| Height (Inches) |
12 |
12 |
17 |
17 |
| Depth (Inches) |
18.5 |
18.5 |
18.5 |
18.5 |
* 21/8” x 3” (54mm x 76mm)
diameter adapter is furnished with unit for flue
connection. ** 2” x 4” (51mm x 102mm)
diameter adapter is furnished with
unit for flue connection. *** 3” x 4” (76mm x 102mm) vent diameter
adapter is required (not furnished) for horizontal venting in residential applications.
**** 4” x 5” (102mm x 127mm) vent diameter adapter is required (not
furnished) for horizontal venting in residential applications. |
| Aluminized Steel |
LF24-
100A |
LF24-
125A |
LF24-
150A |
LF24-
200A |
LF24-
250A |
LF24-
300A |
LF24-
345A |
LF24-
400A |
| Stainless Steel |
LF24-
100S
|
LF24-
125S
|
LF24-
150S
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LF24-
200S
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LF24-
250S
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LF24-
300S
|
LF24-
345S
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LF24-
400S
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Heating Capacity
Input Btuh (kw) |
100,000
(29.3) |
125,000
(36.6) |
150,000
(44.0) |
195,000
(56.9) |
250,000
(73.3) |
300,000
(87.9) |
345,000
(101.1) |
390,000
(114.3) |
| Heating Natural |
80,500
(23.6) |
100,625
(29.4) |
120,750
(35.4) |
156,000
(45.6) |
201,250
(59.0) |
241,500
(70.8) |
276,000
(80.9) |
312,000
(91.4) |
Cap. Output LPG/Btuh(kw)
Propane |
82,000 (24.0) |
105,500 (30.9) |
123,000 (36.0) |
156,000 (45.6) |
205,000 (60.1) |
246,000 (72.1) |
281,200
(82.4) |
312,000
(91.4) |
| Steady Nat./LPG |
80.50% |
80.50% |
80.50% |
80.00% |
80.50% |
80.50% |
80.00% |
80.00% |
| State Propane Efficiency |
82.00% |
82.00% |
82.00% |
80.00% |
82.00% |
82.00% |
81.50% |
80.00% |
| Flue Size - Roundin. (mm) |
4(102)* |
4(102)* |
4(102)* |
5(127)** |
5(127)** |
5(127)** |
6(152)*** |
6(152)*** |
GasPipingSize-
in.(mm) |
1/2 (13) |
1/2 (13) |
1/2 (13) |
1/2 (13) |
3/4 (19) |
3/4 (19) |
3/4 (19) |
3/4 (19) |
| Fan Motor Full Load Amps
(total) |
4.1 |
4.1 |
2.1 |
2.1 |
2.1 (4.2) |
2.1 (4.2) |
2.1 (4.2) |
2.1 (4.2) |
| Electrical |
115volts |
115 volts |
115 volts |
115 volts |
115 volts |
115 volts |
115 volts |
115 volts |
| Characteristics |
60 hertz |
60 hertz |
60 hertz |
60 hertz |
60 hertz |
60 hertz |
60 hertz |
60 hertz |
| |
1 phase |
1 phase |
1 phase |
1 phase |
1 phase |
1 phase |
1 phase |
1 phase |
ShippingWeight-
lbs. (kg)
1 Package |
140(64) |
150(68) |
165(75) |
175(79) |
285(129) |
305(138) |
310(141) |
315(143) |
| Width (Inches) |
20.2 |
20.2 |
23.1 |
23.1 |
41.1 |
41.1 |
41.1 |
41.1 |
| Height (Inches) |
32.2 |
32.2 |
32.2 |
32.2 |
32.2 |
32.2 |
32.2 |
32.2 |
| Depth (Inches) |
31.3 |
31.3 |
31.3 |
31.3 |
31.3 |
31.3 |
31.3 |
31.3 |
*21/8” x 4”(54mm
x 102mm) diameter adapter is furnished with unit
for flue connection. **21/4” x 23/4”(57mm
x 70mm) rectangular to 5” (127mm) round
adapter is furnished with unit for flue connection.***21/4” x 23/4”(57mm
x 70mm) rectangular to 6” (152mm) round adapter is furnished with
unit for flue connection. |
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