EcoTemp 95% Single Stage 40K BTU Gas Furnace, WFSX040A030B
The EcoTemp WFSX040A030B is a 40,000 BTU input, 39,000 BTU output condensing gas furnace built for homes where a big furnace would simply be too much. Rated up to 96.0% AFUE in upflow and horizontal positions (95.0% downflow), it pairs a stainless steel secondary heat exchanger with a multi 18-speed constant torque ECM blower in a slim 14-3/16" cabinet. Homeowners replacing an oversized older furnace, contractors finishing condos and townhomes, and remodelers heating tight utility closets will find this the most compact WFSX size in our EcoTemp equipment lineup.
Is a 40,000 BTU Gas Furnace the Right Size?
A 40K furnace makes sense when a heat-load calculation shows a modest design requirement: smaller single-family homes, condos, townhouses, mobile-home replacements (with the approved accessory kit), and well-insulated homes in mild-winter climates. EcoTemp's product data calls for sizing the furnace to cover 100 percent of the calculated design heating load using ACCA Manual J and S or another approved method, and notes that none of the WFSX sizes should be used where the heating load is 12,000 BTUh or lower.
Choosing the smallest furnace that still covers your load matters more with a condensing unit than with an 80% model. The WFSX literature warns that excessive oversizing can cause the furnace or vent to fail prematurely, create comfort complaints, and lead to vent freezing. Window quality, attic and wall insulation, air leakage, duct location, local winter design temperature, and elevation all move the number, so a home that "feels" like it needs more than 40K often does not once the load is actually calculated.
Ideal for: Condos, townhomes, small ranch homes, tight closet or attic installations, and furnace replacements matched to a 2.5-ton-or-smaller air conditioner (1,000 CFM cooling designation).
Need more capacity? Step up to the EcoTemp 95% Single Stage 60K BTU Gas Furnace, WFSX060B048B for homes whose Manual J load exceeds 39,000 BTU output or that need more cooling airflow.
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 | WFSX040A030B — 40,000 BTU Single-Stage Condensing Gas Furnace |
|---|---|
| Heating Input / Output | 40,000 BTUh Input / 39,000 BTUh Output |
| Efficiency | 96.0% AFUE Upflow/Horizontal, 95.0% AFUE Downflow |
| Fuel | Natural Gas (Propane with Factory Conversion Kit) |
| Blower Motor | 1/2 HP Multi 18-Speed Constant Torque ECM |
| Airflow Positions | Multi-Position: Upflow, Downflow, Horizontal Left/Right |
| Electrical | 115V, Single Phase, 60 Hz — 15 Amp Max Breaker |
| Cabinet Width | 14-3/16" W x 35" H |
Everything that matters for a small-load install fits inside one narrow cabinet: two inshot burners, a hot surface silicon nitride igniter, a redundant White-Rodgers gas valve, and a 1/2 HP ECM blower that delivers 705 CFM of heating airflow at rated static. A 40VA transformer supplies the thermostat and accessories, and a 1.25-in. inducer outlet restrictor disk (P/N 1185623) ships in the loose parts bag for short vent runs under 10 ft. total equivalent length. Return-air filter, venting, and thermostat are field supplied.
Furnace Performance & Installation Features
WFSX040A030B Heating & Efficiency
- 40,000 BTUh input with 39,000 BTUh DOE-rated heating output
- Up to 96.0% AFUE in upflow and horizontal positions
- Meets ENERGY STAR version 5.0 South criteria
- Stainless steel secondary heat exchanger for condensing operation
- Insulated heat exchanger compartment
- Two-burner single-stage gas train with 1/2" NPT connection
- 40–70°F certified temperature rise range
- Adjustable heating blower OFF delay: 90, 120, 150, or 180 seconds
- Flame roll-out sensors and high temperature limit control standard
- Meets 40 ng/J NOx requirements in air quality management districts
WFSX040A030B Installation & Service
- Slim 14-3/16" wide, 35" tall cabinet for closets and attics
- Four-position install: upflow, downflow, horizontal left or right
- Direct vent (2-pipe), single-pipe, or ventilated combustion air options
- 1-1/2", 2", or 2-1/2" vent pipe sizing per manufacturer vent tables
- 18 airflow settings with 155–1,000 CFM cooling airflow range
- 3-digit diagnostic display for fault codes and status
- On-board NFC antenna for setup with the service technician app
- 24 VAC humidifier and 115 VAC electronic air cleaner terminals
- Quarter-turn door knobs and slide-out blower assembly
- Minimum 14 AWG wire on a 15 amp time-delay breaker
Specifications & Manuals
Check the 040A030 column of the technical specifications for airflow tables, vent length limits, and the restrictor disk requirement before installation. Shop the full range of 92%+ PVC vented high-efficiency gas furnaces, matching 2.5–3 ton cased coils, and thermostats and controls.
Frequently Asked Questions
What size home is the WFSX040A030B best suited for?
The WFSX040A030B fits homes with a calculated design heating load at or just under its 39,000 BTUh output, typically condos, townhomes, smaller single-family homes, and tight, well-insulated houses. EcoTemp specifies sizing by Manual J or another approved load method rather than square footage alone.
Why does the 40K WFSX ship with an inducer outlet restrictor disk?
Per the WFSX product data, the 1.25-in. restrictor disk (P/N 1185623) included in the loose parts bag is required on 40K installations with less than 10 ft. of total equivalent vent length in all orientations, from 0 to 2,000 ft. elevation. Skipping it can cause flame disturbance or flame-sense lockout.
Will the 14-3/16" WFSX040A030B fit in a closet or attic?
It is the narrowest WFSX cabinet at 14-3/16" wide and 35" tall, and it installs upflow, downflow, or horizontal. Clearances to combustibles are 0" at the rear, sides, and vent, 1" at the front and top, with 24" recommended in front for service. Always confirm local code requirements.
What size air conditioner can share the WFSX040A030B blower?
The "030" in the model number is a 1,000 CFM cooling designation, and the blower covers 155–1,000 CFM in cooling. That generally aligns with a 2.5-ton or smaller single-stage air conditioner; confirm the indoor coil and condenser match with your installer.
Can the WFSX040A030B be vented with 2-inch PVC?
Yes. At 0–2,000 ft. elevation the 40K size allows up to 155 ft. of maximum equivalent vent length on 2" pipe, 40 ft. on 1-1/2" pipe, and 185 ft. on 2-1/2" pipe, before deducting elbows. Use the smallest pipe size that works, since oversizing can cause flame disturbance or terminal icing.
What circuit breaker and wire size does the WFSX040A030B require?
The furnace runs on 115V single-phase power with a unit ampacity of 9.7 amps. The product data lists a minimum 14 AWG wire and a maximum 15 amp fuse or circuit breaker, with a time-delay type recommended.
WFSX Technical Specifications
ICP Warranty Certificate
