Designed for Exceptional Performance
The new LS25 Separated Combustion Unit Heaters utilize high-temperature silicone gaskets to provide a superior seal and leakage rates that are up to 57% lower* than those allowed under ANSI Z83.8. Lennox goes above and beyond to deliver a tight, durable seal because that is the key to unmatched durability and efficiency over the life of a separated combustion product in harsh environments.
Features & Benefits
More Flexibility Keeps Everyone Comfortable.
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˚
*Lennox unit heaters are the most efficient unit heaters in the 80% thermal efficiency class for models that are dual qualified for commercial and residential application, LF25-030 thru LF25-0105
** Lennox tests their products for sound and vibration in a reverberation room which is designed to measure pressure and sound levels during steady state to the standard Section 4.4.4 AHRI 260-2012. The Lennox LF25-200 and Modine 200K BTUH model were compared in May 2019.
***LF25-030 thru LF25-105
Applications and Benefits of Separated Combustion
Separated combustion LS25 models use outside air for combustion and are designed for use in applications where the indoor environment may contain airborne contaminants, VOC’s and/or dust that would normally be harmful to the combustion process and components.
Increased Application Flexibility
- Separated combustion units offer a robust heating solution for buildings with harsh indoor environments
- Fresh-air intake can be rotated 180˚ degrees for increased installation flexibility in retrofit applications which can reduce the number of piping elbows needed to make venting connections
Lower Operating Costs
- The separated combustion technology enhances overall energy efficiency of the building by eliminating the continued replacement of conditioned air with unconditioned outside air.
- Up to 5% more efficient than standard efficiency direct-fired unit heaters**
- LS25-250 through LS25-400 KBTUH models lower operating costs by efficiently meeting the demands of the space of the space with two stages of heating
Specifications for the LS25 Heaters
| Gas Heating Performance | |||
|---|---|---|---|
| Input Heating Capacity BTU/Hr[KW] |
Output Heating Capacity BTU/Hr[KW] |
Efficiency | Temp Rise °F[°C] |
| 125,000 [36.6] | 102,000 [29.9] | 82% | 50 [10] |
| 150,000 [44.0] | 123,000 [36.0] | 82% | 62 [16.7] |
| 175,000 [51.3] | 143,500 [42.1] | 82% | 58 [14.4] |
| 200,000 [58.6] | 164,000 [48.1] | 82% | 59 [15.0] |
| 250,000 [73.3] | 205,000 [60.1] | 82% | 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] |
| Connections | |||
|---|---|---|---|
| Gas Piping Inches |
Flue Size In[MM] |
Combustion Air Size In[MM] |
|
| 1/2 | 4 [102] | 4 [102] | |
| 1/2 | 4 [102] | 4 [102] | |
| 1/2 | 5 [127] | 5 [127] | |
| 1/2 | 5 [127] | 5 [127] | |
| 3/4 | 5 [127] | 5 [127] | |
| 3/4 | 5 [127] | 5 [127] | |
| 3/4 | 6 [152] | 6 [152] | |
| Fan Data | |||
|---|---|---|---|
| Number of Fans | Air Colume CFM[M3/Min] |
Amps @ 115V | Max overcurrent protection |
| 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 |
| Brand | Lennox |
|---|---|
| SKU | LS25 |
| Hazardous Material | false |