Description
Product Summary
The Sterling XF175A1NS1110 is a 175,000 BTU/h gas-fired propeller unit heater from the XF Series. It delivers 145,250 BTU/h at 83% thermal efficiency and moves 2,850 CFM.
The XF is built for warehouses, shops, garages and other commercial spaces. The same unit installs as standard combustion or separated combustion without modification: leave the rear inlet collars open, or pipe outside air to them when the space is dusty, humid or under slight negative pressure.
At a glance: 175,000 BTU/h input, 145,250 BTU/h output, 83% thermal efficiency, 2,850 CFM, 115V single-phase, natural gas, standard or separated combustion. Ships in 3-5 business days.
Key Features
- Convertible venting: standard or separated combustion in one unit, ETL certified for Category I and III venting, horizontal or vertical.
- 20-gauge aluminized steel tubular heat exchanger with in-shot burners and a curved, non-welded serpentine design.
- Power venter with combustion air pressure switch.
- Direct spark ignition with an integrated control board and external LED indicator.
- Redundant single-stage gas valve and 115/24V control transformer.
- Rear burner access and one central control panel for easier service.
- Individually adjustable, removable louvers and a full fan guard.
Sizing and Coverage
Sterling sizes unit heaters from a building heat loss, not from floor area alone. Its application manual uses a short version of the ASHRAE method:
- Subtract your local outdoor design temperature from the indoor temperature you want to hold.
- Measure the exposed wall, glass, roof and floor areas, counting doors as glass.
- Multiply each area by its heat-transfer coefficient and the temperature difference, then add 10% for walls facing prevailing winds.
- Add infiltration: building volume in cubic feet x 1 to 2 air changes per hour x temperature difference ÷ 55.
- The total is the BTU/h of output the unit heaters need to supply.
For a quick estimate before you run the numbers, an insulated shop or warehouse usually needs 40 to 60 BTU/h of output per square foot. At 145,250 BTU/h, that is roughly 2,400 to 3,650 sq ft. Uninsulated metal buildings, tall ceilings and busy overhead doors push the need higher.
Place units so warm air blows toward the walls and doors with the most heat loss, and avoid blowing directly on people. In larger buildings, several heaters around the perimeter work better than one big unit.
| Mounting height (floor to bottom of unit) | Approx. heat throw |
|---|---|
| 8 ft | 75 ft |
| 10 ft | 64 ft |
| 12 ft | 57 ft |
| 15 ft | 49 ft |
Sterling does not recommend mounting this size higher than 15 ft. Throw figures are approximate and assume no discharge nozzle.
Need a different size? The XF series is also available here in 125,000 BTU (XF125A1NS1110), 150,000 BTU (XF150A1NS1110), 200,000 BTU (XF200A1NS1110), 400,000 BTU (XF400A1NS1110).
Specifications
| Brand | Sterling |
|---|---|
| Model | XF175A1NS1110 |
| Series | XF Convertible Venting |
| Heating Input | 175,000 BTU/h |
| Heating Output | 145,250 BTU/h |
| Thermal Efficiency | 83% |
| Airflow | 2,850 CFM |
| Air Temperature Rise | 46 °F |
| Fuel | Natural Gas (field convertible to LP) |
| Ignition | Direct Spark (DSI) |
| Heat Exchanger | 20-gauge aluminized steel tubular |
| Venting | Standard or separated combustion, power vented, Category I & III |
| Flue Size | 5 in |
| Combustion Air Inlet | 5 in |
| Gas Connection | 1/2 in NPT |
| Fan Motor | 1/3 HP PSC (Permanent Split Capacitor), 1,050 RPM |
| Electrical | 115V, 60 Hz, 1-Phase |
| Full Load Amps | 8 A |
| Min. Circuit Ampacity | 9.5 A |
| Dimensions (W x D x H) | 37-1/4 x 32-1/2 x 33-3/4 in |
| Unit Weight | 194 lb |
| Shipping Weight | 244 lb |
| Certification | ETL listed, ANSI Z83.8 |
| Max. Mounting Height | 15 ft to bottom of unit |
| Heat Throw at 8 ft | 75 ft |
| Gas Control | Single stage |
| Altitude Rating | 0–4,999 ft (field derate above 2,000 ft) |
| Motor Enclosure | Open drip proof (ODP) |
| Control Access | Right side |
Installation Requirements
- Clearances: 6 in from the sides and top, 12 in below the unit to combustibles, 6 in from the flue collector, 18 in on the control box side and 18 in behind the unit for inlet air.
- Mounting height: at least 8 ft to the bottom of the unit with the standard fan guard; below 8 ft an OSHA-approved fan guard is required.
- Suspension: hang from the top hanger points with 3/8 in threaded rod.
- Thermostat: keep the setting at 50°F or higher so flue gas does not condense in the aluminized heat exchanger. It is not a freeze-protection heater.
- Location: do not install in corrosive or flammable atmospheres, or where combustion air carries chlorinated or acidic vapors. Use separated combustion in dusty, humid or slightly negative-pressure spaces.
- Altitude: rated up to 2,000 ft; above that, derate input 4% per 1,000 ft (U.S.).
Gas and venting work should be done by a qualified, licensed installer following the National Fuel Gas Code (ANSI Z223.1/NFPA 54) and local codes.
Model Number Breakdown
| Code | Meaning | This unit |
|---|---|---|
| XF | Series | Convertible venting tubular propeller |
| 175 | Capacity | 175,000 BTU/h input |
| A | Furnace type | Right side access |
| 1 | Heat exchanger | Standard aluminized steel |
| N | Gas type | Natural gas |
| S | Altitude | 0–4,999 ft |
| 1 | Gas control | Single stage |
| 1 | Supply voltage | 115/1/60 |
| 1 | Motor type | Open drip proof (ODP) |
| 0 | Blower motor | None (propeller unit) |
Is This the Right Configuration?
The XF175A1NS1110 is the standard build: aluminized steel heat exchanger, single-stage gas valve and open drip proof motor. Sterling's own selection guide recommends a different build in these cases:
- Humid, coastal or corrosive air, or spaces that sit below 40°F: choose a 409 stainless steel heat exchanger, with stainless burners and flue collector. Moisture and salt corrode aluminized steel over time.
- Occupied spaces where steady comfort matters: two-stage or modulating gas control holds temperature more evenly and cycles less. Single stage is the most economical choice for warehouses and storage.
- Dusty spaces (wood shops, textile work): a totally enclosed motor resists clogging better than an open drip proof motor.
- Dust, fumes, high humidity or negative pressure: vent it as separated combustion so the burner draws outside air. This unit converts with the combustion air inlet kit below.
If your space falls into one of these cases, contact us before ordering and we will quote the matching Sterling build.
Compatible Sterling Accessories
| Sterling part number | Description |
|---|---|
| X7-H5 | Horizontal combustion air inlet kit, 5 in, concentric venting (XF 100–250) |
| X7-V5 | Vertical combustion air inlet kit, 5 in, concentric venting (XF 100–250) |
| M2-2 | Vent cap, 5 in (XF 100–250) |
| X2-002 | 30° downturn nozzle (XF 175–250) |
| X3-002 | 60° downturn nozzle (XF 175–250) |
| X4-002 | 90° downturn nozzle (XF 175–250) |
| Q1-2TB | Y-splitter nozzle (XF 175–250) |
| M7 | 2 to 4 point suspension kit |
| G3 | 1-stage thermostat with fan switch |
| G6 | Locking thermostat cover |
| A7 | High pressure gas regulator (supply pressure above 1/2 psi) |
Accessories are special order from Sterling and typically ship in 2–4 weeks. Call or email us to add any of them to your order.
What's Included
- XF175A1NS1110 unit heater with power venter, direct spark ignition controls and fan guard
- Flue collar adapter (field installed per the included instructions)
A 24V thermostat, gas piping, vent pipe, threaded rod and optional accessories (discharge nozzles, combustion air inlet kit, LP conversion parts) are sold separately; see the accessory list above.
Ideal Applications
- Warehouses and distribution spaces
- Manufacturing floors and maintenance shops
- Commercial garages, loading docks and service bays
Frequently Asked Questions
How many square feet will the XF175A1NS1110 heat?
Roughly 2,400 to 3,650 sq ft in an insulated building, based on 40 to 60 BTU/h of output per square foot. Confirm with a heat loss calculation, since insulation, climate and door traffic change the answer.
How high can I mount it?
Up to 15 ft to the bottom of the unit. Mount it at least 8 ft up with the standard fan guard, or add an OSHA-approved guard if it hangs lower.
Do I need separated combustion?
Use separated combustion when the space is dusty, dirty, humid, mildly corrosive or under slight negative pressure. Otherwise standard combustion with indoor air works, and the unit converts either way without modification.
Can it run on propane?
It ships set up for natural gas. LP conversion requires the correct conversion parts from Sterling, installed by a qualified technician.
What venting does it need?
It has a 5 in flue connection for standard combustion. For separated combustion, run a 5 in combustion air pipe to the inlet collar.
What power does it need?
115V, 60 Hz, single-phase. Full load amps are 8 A and minimum circuit ampacity is 9.5 A.
Does it lose capacity at altitude?
Ratings apply from 0 to 2,000 ft. In the U.S., input is derated 4% for each 1,000 ft above sea level. See the installation manual.
What is the warranty?
Sterling covers the heat exchanger, flue collector and burners for 10 years from the date of manufacture, and the rest of the unit for 1 year from factory shipment (or 18 months from manufacture, whichever comes first).
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