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Furnace Replacement Budget Calculator

Furnace replacement runs $3K-$8K typical. Cost drivers: BTU size, AFUE efficiency, fuel type (gas vs electric vs propane), and install complexity. High-efficiency (90%+ AFUE) qualifies for rebates. Electrical requirements matter: high-efficiency furnaces require dedicated 15-20A circuit plus condensate drain. Existing 80% furnace swap is straightforward; stepping to 95% often requires new vent pipe (PVC side-wall), condensate management, and gas line verification. Add $400-$800 for these adjustments. Federal tax credit for qualifying high-efficiency furnaces through 2032 caps at $600 under 25C IRA rules.

%
$

Net total (after rebates)

$4,520

Subtotal

$5,120

Unit cost

$3,920

Vent upgrade cost

$0

How the math works

80K BTU 95% AFUE gas furnace: $3,520 unit + $1,200 install − $600 rebates = $4,120. Propane: slightly more. Electric (heat pump) runs $4K-$7K.

Size to Manual J load calculation, not gut feel. HVAC contractors rushing through calcs often oversize — leads to comfort and efficiency problems. Ask specifically for Manual J.

How to Use

  1. Enter BTU need, AFUE rating, and fuel type.
  2. See total cost.

Frequently Asked Questions

What BTU do I need?

40 BTU per sqft in cold climates; 25 BTU in warm. 2,000 sqft cold climate: 80,000 BTU furnace. Sizing too large = short-cycling + poor comfort. Too small = running constantly.

High-efficiency worth it?

Yes in cold climates. 96% AFUE costs 15-20% more than 80% AFUE but saves $200-$500/yr on gas bills. 5-7 year payback. Federal tax credit adds up to $600 for qualifying units 2023-2032.

Venting?

80% AFUE: conventional chimney. 90%+: side-wall PVC vent. If converting chimney to side-wall: add $500-$1,000. Usually done anyway.

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