The Sterling AF series gas unit heaters are a great heating option for large greenhouses, car washes, and structures in coastal areas. Sterling AF heaters feature: stainless steel tubular heat exchanger, electronic ignition, power exhaust system, advanced diagnostic system for dependable worry-free operation, lots of safety features, totally enclosed fan to provide even heat distribution, and ZAM coated cabinet made to protect them from harsh environments. They are designed for suspended mounting and require only a vent pipe and connections to a gas and electric line for installation. Some wiring required. Requires 110/120v electricity. Designed for propane or natural gas.
ZAM® coating is a high-performance, hot-dip zinc-aluminum-magnesium alloy coating offering superior corrosion resistance (10–20 times better than standard galvanized steel) through a self-healing layer which is ideal for harsh, coastal, and agricultural environments.
Sterling AF Heater Exclusive Features
- ZAM coated cabinet for harsh environments
- Stainless steel heat exchanger and burner are standard
- Sealed, totally enclosed fan motor
- Added 5 year warranty on cabinet
Sterling Heater Features
- 83% efficient
- Made in the USA
- Separated combustion ready
- Certified for commercial and industrial use
- Direct spark ignition
- Power vented exhaust
- Convenient diagnostic light and thermostat connections on outside casing
- 10 year warranty on the burner and heat exchanger
Heater Upgrade Options
Extended Parts Warranty
This extends the included 1 year parts warranty to 3 years. If replacement parts are needed, they will be provided no charge and shipped for free during the life of the warranty. Click here for terms
Heater Gas Type Setup
The heater will come equipped from the factory for whichever gas type you choose.
2 Stage Gas Valve
Heaters with a two-stage gas valve start on the 1st stage at half output and only switch to the 2nd stage, full output, if the temperature inside the room continues to drop. This allows the heater to run more efficiently saving gas and money. Units with 2 stage valves ship direct from Sterling. The current ship time is listed in the option selection area above. Must be ordered with heater.
Elevation
If the heater will be installed at a location that is over 5000' above sea level, Sterling makes a special high altitude model for this application. Units setup for high altitude (above 5000') ship direct from Sterling. The current ship time is listed in the option selection area above. Must be ordered with heater.
Performance Specifications
| Model
|
BTU Input
|
BTU Output
|
W x D x H
|
Weight (lbs)
|
| AF100
|
100,000
|
83,000
|
25 1/4" x 43 1/2" x 33 1/4"
|
175
|
| AF125
|
125,000
|
103,750
|
25 1/4" x 43 1/2" x 33 1/4"
|
187
|
| AF150
|
150,000
|
124,500
|
25 1/4" x 43 1/2" x 33 1/4"
|
197
|
| AF175
|
175,000
|
145,250
|
37 1/4" x 43 1/2" x 33 1/4"
|
244
|
| AF200
|
200,000
|
166,000
|
37 1/4" x 43 1/2" x 33 1/4"
|
254
|
| AF250
|
250,000
|
207,500
|
37 1/4" x 43 1/2" x 33 1/4"
|
264
|
| AF300
|
300,000
|
249,000
|
55 1/4" x 44 3/4" x 34"
|
371
|
| AF400
|
400,000
|
332,000
|
55 1/4" x 44 3/4" x 34"
|
399
|

Sterling AF Heater Specs and Dimensions - Includes all of the Sterling AF heater dimensions and performance data.
Sterling AF Heater Installation Manual - Complete instruction manual that comes with each Sterling AF heater.
Sterling AF Heater Thermostat Wiring Diagrams - Includes wiring diagrams for the most common thermostats.
Greenhouse Heater Size Calculator
Item # 4071710, 4071715 Model # AF125A2NS112, AF125A2PS112, AF125A2NS212, AF125A2PS212