Furnace Types & Guide

Furnace sizing is measured in BTUs (British Thermal Units). Rough estimate: 30-60 BTUs per square foot depending on climate, insulation, and other factors. A 2,000 sq ft home typically needs 60,000-100,000 BTU furnace. Always get a professional Manual J load calculation—oversized furnaces short-cycle, while undersized ones run constantly.

Gas furnaces typically last 15-20 years, electric furnaces 20-30 years. Factors affecting lifespan: quality of installation, maintenance frequency, usage levels, and climate. Signs of an aging furnace: frequent repairs, uneven heating, increased energy bills, unusual noises, and yellow burner flame (should be blue).

High-efficiency (90%+ AFUE) furnaces cost $1,000-$2,000 more upfront but save 10-20% on heating bills. They're most cost-effective in cold climates with heavy heating use. In mild climates with minimal heating needs, the savings may not justify the higher cost. Also consider available rebates and incentives.

Gas furnaces cost more to install but less to operate (natural gas is usually cheaper than electricity). Electric furnaces are simpler, safer, and last longer, but operating costs are higher. In areas without natural gas access, electric or propane are the options. Heat pumps are increasingly popular as an efficient electric alternative.