Furnaces

Modern residential furnaces achieve 80% to 96%+ AFUE (Annual Fuel Utilization Efficiency) ratings — meaning 80-96 cents of every dollar spent on fuel is converted into usable heat, with the remainder lost through the flue. High-efficiency condensing furnaces at 95%+ AFUE use a secondary heat exchanger to extract additional heat from combustion gases that would otherwise escape, delivering significantly lower operating costs and qualifying for utility rebates and tax credits.

The Trade Table carries furnaces from Empire and MRCOOL — covering central gas furnaces, wall-mount furnaces, B-vent furnaces, direct vent furnaces, and counterflow models from 20,000 BTU through 120,000 BTU for residential, garage, workshop, and supplemental heating applications.

Furnaces | Gas, Wall, B-Vent & Direct Vent Heating Systems

A central furnace heats air at a single location and distributes warmed air throughout the home through supply ductwork to registers in each room. Cooler return air flows back to the furnace through return ductwork, where it is reheated and recirculated. The MRCOOL VersaPro and Signature Series are central upflow, downflow, and horizontal gas furnaces ranging from 40,000 BTU through 120,000 BTU — covering small homes through large residential installations and light commercial applications.

Wall furnaces install directly into an interior wall and heat the surrounding space without ductwork — ideal for room additions, garages, basements, accessory dwelling units, cabins, and homes without central heating systems. Empire wall furnaces are available in B-vent gravity, direct vent, and vented counterflow configurations from 25,000 BTU through 55,000 BTU, with both natural gas and propane options to fit any fuel supply.

Direct vent furnaces use a sealed combustion system with two coaxial vent pipes — one bringing combustion air from outside, one exhausting flue gases. The sealed combustion design eliminates indoor air consumption and prevents backdrafting, making direct vent furnaces the safest residential furnace configuration. Empire direct vent wall furnaces install with a single wall penetration and require no chimney or B-vent infrastructure.

B-vent furnaces use atmospheric venting through a Type B double-wall vent pipe routed vertically through the roof. B-vent gravity furnaces draw combustion air from the indoor space and rely on natural convection (heated air rising) to distribute warmth — eliminating the need for a blower motor and electrical connection in basic configurations. The Empire B-vent gravity wall furnace lineup covers 25,000 BTU, 35,000 BTU, and 50,000 BTU configurations in both natural gas and propane.

Counterflow vented wall furnaces deliver heat downward at floor level — the opposite of conventional heaters that warm the ceiling first and rely on convection to reach occupants. Counterflow design provides faster comfort at floor level and works particularly well in mobile homes, manufactured homes, and elevated room installations. Empire counterflow wall furnaces range from 40,000 BTU through 55,000 BTU.

MRCOOL VersaPro central furnaces feature 80% AFUE single-stage performance with DC motor blowers and upflow, downflow, and horizontal installation flexibility. MRCOOL Signature Series furnaces step up to 96% AFUE high-efficiency condensing performance with multi-speed motors for variable-load operation and significantly lower operating costs. Both series cover 40,000 BTU through 120,000 BTU capacities for residential whole-home heating.

Furnace Options

• MRCOOL VersaPro 80% AFUE central gas furnaces from 40,000 to 120,000 BTU
• MRCOOL Signature Series 96% AFUE high-efficiency condensing furnaces
• MRCOOL Signature Series 80% AFUE multi-speed ECM motor furnaces
• Empire B-vent gravity wall furnaces in 25K, 35K, and 50K BTU
• Empire direct vent wall furnaces with sealed combustion
• Empire vented counterflow wall furnaces from 40K to 55K BTU
• Natural gas and propane fuel options across all configurations
• Upflow, downflow, and horizontal central furnace orientations
• Single-stage and multi-speed motor configurations
• Multiple cabinet sizes (A, B, C, D) matching airflow requirements
• 20,000, 40,000, 50,000, and 55,000+ BTU sizing tiers
• Millivolt control, electronic intermittent pilot, and standing pilot ignition

Benefits of Furnaces

• Whole-home heating performance through central duct distribution
• Wall-mount options for ductless single-room and supplemental heating
• 80% to 96%+ AFUE efficiency tiers for any budget and energy goal
• Sealed combustion direct vent options for maximum safety
• Natural gas and propane fuel flexibility
• Faster heat output than heat pumps in cold climates
• Lower operating cost than electric heating in most regions
• Long service life — 15-25+ years with proper maintenance

Common Uses for Furnaces

• Whole-home central heating with ducted distribution
• Single-room heating for additions, garages, and basements
• Mobile homes and manufactured housing with counterflow configurations
• Garage and workshop heating with B-vent or direct vent wall units
• Cabins and rural properties with propane wall furnace installations
• Replacement of aging central furnaces with high-efficiency upgrades
• New construction builds specifying central heating systems
• Supplemental heating in spaces underserved by central HVAC
• Off-grid and emergency heating with millivolt-controlled gravity furnaces

Why Buy Furnaces from The Trade Table?

The Trade Table helps customers select the right furnace based on heating load, installation type (central ducted vs wall-mount), fuel type (natural gas vs propane), efficiency tier (80% vs 96% AFUE), and venting configuration (B-vent vs direct vent vs counterflow). Our team provides guidance on BTU sizing for the heated square footage, choosing between MRCOOL central furnaces and Empire wall units, and specifying ignition and control systems. We carry furnaces from MRCOOL and Empire across the full range from 20,000 to 120,000 BTU.

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Furnace FAQs

What size furnace do I need?

Furnace BTU sizing is based on the heated square footage with adjustments for climate zone, insulation quality, ceiling height, and window area. General sizing rule by climate zone: warm southern climates need 30-35 BTU per sq ft, moderate climates need 35-45 BTU per sq ft, cold northern climates need 45-60 BTU per sq ft. Practical sizing examples: a 1,500 sq ft home in a moderate climate needs approximately 60,000-70,000 BTU. A 2,500 sq ft home in a cold climate needs 100,000-120,000 BTU. A Manual J load calculation provides the most accurate sizing.

What is the difference between 80% AFUE and 96% AFUE furnaces?

AFUE (Annual Fuel Utilization Efficiency) measures how much of the fuel's energy is converted into usable heat versus lost through the flue. An 80% AFUE furnace converts 80 cents of every dollar spent on fuel into heat, with 20 cents lost. A 96% AFUE high-efficiency condensing furnace converts 96 cents of every dollar into heat — using a secondary heat exchanger to extract additional energy from combustion gases that would otherwise escape. 96% AFUE furnaces cost more upfront but deliver significantly lower operating costs over the furnace's lifetime, often qualifying for utility rebates and tax credits.

What is the difference between B-vent and direct vent furnaces?

A B-vent furnace uses atmospheric venting through a Type B double-wall vent pipe routed vertically through the roof — drawing combustion air from the indoor space. A direct vent furnace uses a sealed combustion system with two coaxial vent pipes routed horizontally through an exterior wall — one bringing combustion air from outside, one exhausting flue gases. Direct vent is the safer option because the sealed combustion eliminates indoor air consumption and prevents backdrafting. B-vent is simpler and less expensive but requires adequate indoor air supply.

How much does a furnace cost?

Furnace costs vary by type, capacity, and efficiency tier. Wall furnaces from Empire run $1,200-$3,500 depending on BTU output, vent type, and fuel. Central gas furnaces from MRCOOL run $1,150-$2,100 for the equipment alone, varying by BTU and efficiency rating. Professional installation typically adds $1,500-$4,000 for central furnaces and $800-$2,000 for wall furnaces. Total installed cost runs $2,500-$6,500 for residential central furnaces and $2,000-$5,500 for wall furnace installations.

Should I choose natural gas or propane?

Natural gas is the preferred fuel where utility gas service is available — lower cost per BTU, no on-site fuel storage, and consistent supply. Propane is the right choice for rural properties, off-grid installations, and homes without natural gas service — requiring an on-site propane tank with periodic refilling. Most Empire and MRCOOL furnace models are available in both natural gas and propane configurations or include conversion kits for field conversion between fuels.

How long does a furnace last?

Quality residential furnaces last 15-25 years with proper installation and maintenance. Factors affecting lifespan include annual professional maintenance, regular air filter replacement, proper sizing (oversized furnaces short-cycle and wear faster), and water quality for condensing furnaces (96% AFUE models produce condensate that can corrode internal components if drainage is improper). Wall furnaces typically last 15-20 years. Central furnaces last 18-25 years. High-efficiency condensing furnaces match standard furnace lifespans when installed correctly.