Lennox LF25 Unit Heater with Stainless Steel Heat Exchange - 175,000 BTU

More Flexibility Keeps Everyone Comfortable

Lennox heating products are available in three unit designs to meet a wide range of commercial and residential applications. With fourteen available heating capacities, it’s easy to find the right size heater to keep your spaces comfortable. Horizontal and vertical wall venting options, as well as the 180° installation* capability, allow the units to be placed in a number of locations.

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Benefits of the LF25 Heater

• Available with Aluminized or Stainless Steel heat exchanger
• Ideal for a wide range of commercial and residential applications
• Heating capacities from 30,000–400,000 BTU/h
• Up to 83.8% thermal efficiency
• Stainless steel heat exchanger available on 125,000 - 400,000 BTU/h
• Sidewall venting eliminates roof penetrations
• Self-diagnostic board with LED display improves troubleshooting efficiency and accuracy

Engineered for Maxmimum Efficiency

Lennox heating products are designed for superior reliability and peak performance, year after year. Advanced engineering and high-quality components produce a durable product that delivers comfort with maximum efficiency.

Tubular Heat Exchanger

A standard feature of all Lennox unit heaters is the dimpled, tubular heat exchanger, designed to enhance performance and reliability. The dimples maximizes efficiency and provides excellent heat transfer by completely exposing the heating surface to the air stream. This tubular construction minimizes air resistance to allow for even heating across all surfaces increasing reliability.

Enhanced Features

All unit heater models offer standard features such as the ignitor, flame sensor, high limit switch. Hinged access doors allow easy access to the DSI control board featuring 11 diagnostic codes to quickly determine the unit’s status. Additionally, all unit heaters include an in-shot cluster burner assembly that’s simple to clean and easy to reach.

Efficient By Design

Lennox unit heaters are designed for superior reliability and long-lasting peak performance thanks to advanced engineering and high-quality components.

• Most efficient non-condensing unit heater in the industry*
• Delivers maximum performance through dimpled tubular heat exchanger design
• Superior separated combustion seals through use of high-temperature silicone gaskets

Ultimate Sound Quality

The 25 series unit heaters were engineered to provide a warm and peaceful environment.

• Superior sound quality with 25% less pure tones and projection than leading competitors**
• Quieter space through improved chassis, mounting grill, and fan components

Simplified Installation & Service

Easily install and service Lennox unit heaters.

• Easy set-up and service with 180˚ installation position capability***
• Shorten service calls. by utilizing the new DSI board
• Separated Combustion fresh-air intake box can be rotated 180˚

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Applications for the LF25 Unit Heaters

The LF25 gas-fired unit heaters are a reliable, low cost heating solution designed to provide comfort for a variety applications ranging from residential garages to loading docks to large warehouses.

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Specifications for the LF25 Heaters

Gas Heating Performance
Input Heating Capacity BTU/Hr[KW]	Output Heating Capacity BTU/Hr[KW]	Efficiency	Temp Rise °F[°C]
30,000 [8.8]	24,900 [7.3]	83.4%	37 [2.8]
45,000 [13.2]	37,375 [11.0]	83.7%	52 [11.1]
60,000 [17.6]	49,800 [14.6]	83.7%	47 [8.3]
75,000 [22.0]	62,250 [18.3]	83.4%	65 [18.3]
90,000 [26.4]	74,700 [21.9]	83.8%	43 [6.1]
105,000 [30.8]	87,150 [25.6]	83.5%	59 [15.0]
125,000 [36.6]	103,750 [30.4]	83%	50 [10]
150,000 [44.0]	124,500 [36.5]	82%	62 [16.7]
175,000 [51.3]	145,250 [42.6]	83%	58 [14.4]
200,000 [58.6]	166,000 [48.6]	83%	59 [15.0]
250,000 [73.3]	207,500 [60.8]	83%	51 [10.6]
300,000 [87.9]	246,000 [72.1]	82%	57 [13.9]
400,000 [117.2]	328,000 [96.1]	82%	65 [18.3]

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Connections
Gas Piping Inches	Flue Size In[MM]
1/2	4 [102]
1/2	4 [102]
1/2	4 [102]
1/2	4 [102]
1/2	4 [102]
1/2	4 [102]
1/2	4 [102]
1/2	4 [102]
1/2	5 [127]
1/2	5 [127]
3/4	5 [127]
3/4	5 [127]
3/4	6 [152]

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Fan Data
Number of Fans	Air Colume CFM[M3/Min]	Amps @ 115V	Max overcurrent protection
1	1625 [17.7]	2	15
1	665 [18.8]	2	15
1	1000 [28.3]	2	15
1	1200 [34.0]	2	15
1	1600 [45.3]	2	15
1	1500 [42.5]	2	15
1	1950 [55.2]	5	15
1	1950 [55.2]	5	15
1	2350 [66.5]	7	15
1	2350 [66.5]	7	15
2	4000 [113.3]	8	15
2	5500 [155.7]	8	15
2	5500 [155.7]	11	15