High Heating Bills

Rule out the obvious first

Compare the same billing month year over year rather than month to month. Northern Colorado weather swings hard, and a December with a long cold stretch will always cost more than a mild one. Also check whether your utility rate changed, whether the household added occupants or a home office, and whether the thermostat schedule was altered.

If usage is genuinely higher for comparable weather, then it is worth looking at the system.

Equipment-side causes

• A furnace running longer to make up for restricted airflow — see weak furnace airflow
• Dirty burners or drifting gas pressure reducing combustion efficiency
• Short cycling, where repeated warm-up and purge cycles waste fuel
• A blower stuck in continuous operation, adding electrical cost — see furnace keeps running
• An aging furnace whose original efficiency rating was substantially lower than current equipment
• Deferred maintenance in general; a tune-up frequently recovers lost efficiency

Distribution losses

Duct leakage is one of the most under-appreciated costs in a forced-air home. Supply ducts running through an unconditioned crawlspace, attic or garage lose heat through both leakage and conduction. Every cubic foot of heated air that escapes before reaching a register is fuel purchased and wasted.

Sealing accessible joints with mastic and insulating ducts in unconditioned space is usually a better return than upgrading equipment, and it makes any future replacement perform closer to its rating.

The house itself

Attic insulation depth, air sealing at top plates and can lights, weatherstripping, and window condition all affect how hard the furnace has to work. Many older Old Town and Midtown homes in Fort Collins have been partially upgraded over the years, leaving a mix of well-sealed and untouched areas. A home energy assessment identifies where the losses actually are rather than where they are assumed to be.

Fort Collins Utilities publishes residential efficiency resources and program information for local customers. Program details and eligibility change, so verify current offerings directly at fcgov.com/utilities rather than assuming a particular project qualifies.

Thermostat behavior

Setbacks work, but aggressive setbacks on a home with a marginal system can cause long recovery runs. Smart thermostats that learn recovery time usually handle this well. Make sure the fan is on AUTO unless you have a specific reason for circulation, and confirm any two-stage equipment is configured to actually use its low stage — low-stage operation is where much of the efficiency lives.

Deciding what to spend

Sequence matters: maintenance and airflow first, duct sealing second, envelope improvements third, equipment replacement last. Replacing a furnace in a leaky house simply buys a more efficient way to heat the attic. Our furnace efficiency guide and furnace replacement cost pages walk through the tradeoffs with no pressure to upgrade.