EcoTemp 95% Single Stage 120K BTU Gas Furnace, WFSX120D066B
At the top of the WFSX sizes we carry, the EcoTemp WFSX120D066B delivers 116,000 BTU of heating output from a 120,000 BTU input, with six burners and a 1 HP constant torque ECM blower capable of up to 2,240 CFM in cooling mode. It reaches 96.1% AFUE in upflow and horizontal installations and 95.0% downflow, inside a 24-1/2" wide condensing cabinet. This is the size for very large homes, high heat-loss properties in cold climates, and contractors replacing oversized legacy furnaces who still want a single, high-efficiency, PVC-vented appliance. Pair it with the right cased evaporator coil for whole-home comfort year-round.
Is a 120,000 BTU Gas Furnace the Right Size?
A 120K furnace is reserved for the largest residential heating loads: expansive custom homes, older drafty houses in northern climates, and homes with high ceilings or large glass areas. Because oversizing a condensing furnace can lead to customer discomfort, vent freezing, and premature failure, EcoTemp's literature requires selecting the furnace from a design heat-load calculation (ACCA Manual J and S, ASHRAE, or an equivalent method) rather than replacing like-for-like by input rating.
Before choosing this size, confirm the duct system can carry high airflow. The WFSX120D066B's default heating setting moves roughly 2,015 CFM at low static, and any airflow above 1,800 CFM requires a bottom, two-side, or bottom-and-side return with at least a 20" x 25" filter. Elevation, return-air temperature (60°F–80°F continuous), and the size of the matching air conditioner all factor into a successful installation.
Ideal for: Very large homes, cold-climate high heat-loss properties, and installations needing maximum heating output plus high-volume cooling airflow from one furnace.
Need more capacity? The WFSX series is approved for twinning applications with the manufacturer's accessory kit, or compare the EcoTemp 95% Single Stage 100K BTU Gas Furnace, WFSX100C060B if your load calculation comes in lower than expected.
Recommended heating applications are general guidelines only. Actual furnace sizing depends on a heat-load calculation, insulation, climate, ductwork, elevation, and air-conditioning match. Request free sizing assistance, contact Budget Heating, or call 813-885-7999.
What's Included
| Gas Furnace | WFSX120D066B — 120,000 BTU Single-Stage Condensing Gas Furnace |
|---|---|
| Heating Input / Output | 120,000 BTUh Input / 116,000 BTUh Output |
| Efficiency | 96.1% AFUE Upflow/Horizontal, 95.0% AFUE Downflow |
| Fuel | Natural Gas (Propane with Factory Conversion Kit) |
| Blower Motor | 1 HP Multi 18-Speed Constant Torque ECM |
| Airflow Positions | Multi-Position: Upflow, Downflow, Horizontal Left/Right |
| Electrical | 115V, Single Phase, 60 Hz — 20 Amp Max Breaker |
| Cabinet Width | 24-1/2" W x 35" H |
The largest cabinet in the series houses six inshot burners, a redundant White-Rodgers gas valve, silicon nitride ignition, and the widest blower wheel in the WFSX family at 11" x 11", driven by a 1 HP ECM motor. Rated heating airflow is 1,965 CFM at 0.20 in. w.c., and the unit ships at 181 lb. Unit ampacity is 17.4 amps on 115V, requiring 12 AWG minimum wire and a 20 amp breaker. For downflow or horizontal installs with less than 5 ft. of total equivalent vent length, a 1.50-in. inducer outlet restrictor disk (P/N 1188589) is required and sold separately through FAST Parts.
Furnace Performance & Installation Features
WFSX120D066B Heating & Efficiency
- Highest WFSX output we carry: 116,000 BTUh
- Six-burner single-stage gas train, 1/2" NPT gas inlet
- 96.1% AFUE upflow/horizontal, 95.0% downflow
- Meets ENERGY STAR version 5.0 South criteria
- Stainless steel secondary heat exchanger
- Default heating airflow setting #14 (designated range 11–14)
- Natural gas inlet pressure 4.5–13.6 in. w.c.
- High temperature limit control designed to prevent overheating
- Manual-reset flame rollout protection
- 40 ng/J NOx compliant for air quality districts
WFSX120D066B Installation & Service
- 24-1/2" wide cabinet with 22-7/8" supply outlet
- Up to 2,240 CFM cooling airflow from the 1 HP ECM blower
- Multi-position: upflow, downflow, or horizontal left/right
- Venting on 2-1/2", 3", or 4" pipe per manufacturer tables
- Through-the-casing flue option for counterflow or horizontal
- Approved for twinning with manufacturer's accessory kit
- 40VA transformer with 35VA available for cooling controls
- Humidifier (24 VAC) and electronic air cleaner (115 VAC) terminals
- Quarter-turn knobs for quick door removal
- 3-digit diagnostic display and NFC-enabled setup
Specifications & Manuals
The 120D066 sections of these documents include the restrictor disk requirement, high-airflow return guidance, and 120,000 BTUH vent tables. Pick up condensate pumps and treatment, HVAC installation supplies, and non-programmable thermostats.
Frequently Asked Questions
Is the WFSX120D066B the largest furnace in the EcoTemp WFSX line at Budget Heating?
Yes. Among the WFSX sizes we carry (40K, 60K, 80K, 100K, and 120K), the WFSX120D066B has the highest input, output, burner count, and cabinet width.
How many burners does the WFSX120D066B use?
Six burners, compared with five on the 100K and four on the 60K and 80K models. All fire through a single-stage redundant White-Rodgers gas valve with silicon nitride hot surface ignition.
What clearances does the WFSX120D066B need from combustible materials?
Per the product data: 0" rear, sides, and vent; 1" front, top, and all sides of the supply plenum; and 24" in front for service. Local building codes may require more.
Can two WFSX120D066B furnaces be twinned?
The WFSX series is approved for twinning applications when the manufacturer's approved twinning accessory kit is used, ordered separately. Follow the kit and installation instructions for wiring and duct layout.
What warranty covers the WFSX120D066B heat exchanger?
EcoTemp lists a 20-year heat exchanger limited warranty, a 1-year unit replacement limited warranty, and a 5-year parts limited warranty that extends to 10 years with timely registration (within 90 days at productregistration.icpusa.com). Residential applications only; see the ICP warranty certificate for full terms.
What return-air temperatures can the WFSX120D066B handle?
The furnace is designed for a continuous return-air temperature of at least 60°F, or intermittent operation down to 55°F such as night setback, and return air must not exceed 80°F. Staying within these limits protects the heat exchangers, motors, and controls.
WFSX Technical Specifications
ICP Warranty Certificate
