A space heater usually costs $25-$250 to buy, while replacing a central gas furnace commonly runs $3,800-$10,000 installed. The cheaper choice for a particular home depends on how many rooms need heat, how long the equipment runs, local electricity and gas rates, and whether a furnace already exists.
This comparison uses portable electric resistance heaters and a natural-gas forced-air furnace; heat pumps and electric furnaces have different costs. A space heater costs less upfront, but heating several occupied rooms for long periods can make central heat less expensive to operate.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Portable electric space heater | $25 | $75 | $250 | Basic to feature-rich unit, before electricity |
| Gas furnace replacement | $3,800 | $6,500 | $10,000 | Equipment and standard installation |
| Space heater electricity | $0.15/hour | $0.24/hour | $0.36/hour | 1.5-kW heater at $0.10-$0.24/kWh |
| Gas furnace fuel | $0.80/hour | $1.20/hour | $1.60/hour | 80,000-Btu input, fuel at $1-$2/therm |
What a space heater and gas furnace cost to buy
A portable electric heater generally costs $25-$250, with many 1,500-watt ceramic and infrared models priced around $40-$120. Oil-filled radiators and models with thermostats, timers, or quieter operation may cost $60-$180. Specialty designs or larger units can reach $250, but higher purchase price does not usually mean lower electricity use at the same heat output.
A replacement gas furnace typically costs $3,800-$10,000 installed, with a common midrange project near $6,500. The range assumes a standard residential forced-air system and accessible existing ductwork and gas service. A basic 80% AFUE furnace may be less expensive than a high-efficiency 95%-98% AFUE model, which can require compatible venting and condensate drainage.
For one room, a heater’s low purchase price is compelling; for whole-home heat, compare the installed furnace quote with the cost of running multiple heaters. A new furnace installation where no usable ducts or gas connection exist can cost substantially more than a like-for-like replacement, so those projects need an on-site estimate.
Assumptions: U.S. residential pricing, standard equipment, normal access, and no major duct, electrical, gas-line, or structural changes.
How furnace equipment, labor, and venting shape the quote
A furnace quote includes more than the equipment cabinet. Ask whether it covers removal of the old unit, thermostat work, startup testing, permits, venting, and any duct changes. A low bid that excludes required work may not be comparable with a complete replacement price.
| Quote component | Typical range | What changes the charge | Pricing basis |
|---|---|---|---|
| Gas furnace equipment | $1,500-$4,000 | Capacity, efficiency, brand, features | Per furnace |
| Installation labor | $1,200-$3,000 | Removal, access, crew time, complexity | Often 6-10 hours |
| Venting and drain work | $200-$1,200 | High-efficiency vent route and condensate setup | Project allowance |
| Permit and inspection | $50-$500 | Municipality and project requirements | Per project |
| Removal and disposal | $100-$400 | Old equipment weight and disposal rules | Per unit |
These figures are component ranges, not amounts to add automatically; some contractors bundle equipment, labor, and disposal. For a space heater, the purchase price normally excludes operating electricity, but installation is usually unnecessary when the unit plugs into a suitable outlet.
Confirm the furnace’s model, capacity, efficiency, included work, and warranty in writing before comparing totals.
How room size, heater wattage, and furnace efficiency affect bills
A typical portable heater draws 1,500 watts on its high setting. At electricity rates of $0.10-$0.24 per kilowatt-hour, that is about $0.15-$0.36 per operating hour. At a $0.16/kWh rate, eight hours of continuous high output costs about $1.92, or roughly $58 over 30 days. Thermostat cycling can lower actual use, while a cold, poorly insulated room may keep the heater running longer.
A gas furnace’s hourly expense depends on its input capacity and local gas price. An 80,000-Btu-per-hour furnace uses 0.8 therm per hour at full input; at $1.50 per therm, that is $1.20 per full-input hour before accounting for cycling. Furnaces generally run intermittently rather than at full input all day, so this calculation is a comparison tool, not a monthly bill forecast.
Efficiency changes how much purchased fuel becomes delivered heat. An 80% AFUE furnace delivers about 80,000 Btu of heat for each 100,000 Btu of gas input; a 96% model delivers about 96,000 Btu. At $1.50 per therm, that equates to approximately $18.75 versus $15.63 per million Btu delivered, excluding blower electricity and fixed utility charges.
One 1,500-watt heater is often economical for a small occupied room, but multiple heaters can consume 3-4.5 kW combined. Room dimensions, drafts, insulation, ceiling height, thermostat setting, and daily run time matter as much as the equipment’s listed price.
When does a space heater beat central furnace heat?
For a household using one room for a limited portion of the day, heating only that room can avoid warming unoccupied areas. For example, a 1,500-watt heater used four hours daily at $0.16/kWh costs about $29 monthly over 30 days. If that use replaces furnace heating that would otherwise run for the whole home, the heater may reduce the bill, although the actual savings depend on furnace cycling and thermostat behavior.
For a two-heater setup, two 1,500-watt units running eight hours daily at the same rate cost about $230 monthly: 3 kW × 8 hours × 30 days × $0.16. This may approach or exceed the incremental gas cost of heating a home with a furnace, especially in cold weather. It also requires appropriate circuits; avoid plugging high-wattage heaters into overloaded extension cords or power strips.
Consider a simple break-even comparison: estimate heater kilowatt-hours from wattage, hours, and days, then multiply by the electric rate. Compare that amount with the furnace’s added fuel and blower-electricity cost for the same period. The comparison is not a direct one-to-one unless both options keep the same rooms at similar temperatures.
Targeted heating is most likely to save money when the heated area and schedule are genuinely smaller than the furnace’s normal workload. Lowering the central thermostat while using a heater can help, but large temperature differences between rooms may affect comfort and plumbing protection.
Three household heating examples with monthly estimates
These examples use electricity at $0.16/kWh and gas at $1.50 per therm. Furnace figures show fuel at full input during the stated equivalent run time, before blower electricity and cycling effects; real monthly bills vary with weather, insulation, and thermostat control.
| Scenario | Equipment and use | Estimated energy cost | What it illustrates |
|---|---|---|---|
| One occupied bedroom | 1.5-kW heater, 4 hours/day, 30 days | $29/month | Targeted short-duration heat |
| Two rooms, extended use | Two 1.5-kW heaters, 8 hours/day, 30 days | $230/month | Combined electricity use rises quickly |
| Furnace comparison | 80,000-Btu gas input, 4 equivalent full-input hours/day, 30 days | $144/month in gas | 0.8 therm/hour × $1.50 × 120 hours |
These are illustrative energy calculations, not predictions of whole-home bills. The furnace example assumes the stated equivalent full-input runtime; a modulating or cycling system may deliver the same comfort with a different runtime pattern. A furnace also heats areas beyond the room where a heater is placed, so comfort and heated square footage must be considered alongside dollars.
Why electricity rates and cold climates shift the comparison
Electricity prices vary substantially by utility, and the cost of a 1.5-kW heater follows that rate directly. At $0.10/kWh, eight hours daily for 30 days is about $36; at $0.24/kWh, it is about $86. Gas prices also vary by region and season, so local bills or utility rate schedules provide a better estimate than a national average.
Cold climates increase heating hours and make whole-home heating economics more important. In mild regions, a portable heater may cover occasional chilly mornings; in a long heating season, several heaters used daily can accumulate significant charges. Urban installation labor and permit fees may be 10%-25% higher than comparable rural work in some markets, while travel distance or limited contractor availability can raise rural quotes.
Use local utility rates and the home’s expected heating schedule, not a single national hourly figure, to compare operating costs. A furnace replacement quote should also identify whether gas service, venting, or duct repairs are included, since regional code requirements and site conditions differ.
How long furnace replacement takes compared with heater setup
A portable heater usually needs no professional installation, but its circuit must support the load and the manufacturer’s clearance instructions must be followed. A 1,500-watt heater draws about 12.5 amps on a 120-volt circuit, leaving limited capacity for other devices on the same circuit. Adding a dedicated circuit can cost roughly $250-$900, depending on panel capacity, wiring distance, and local labor.
A standard furnace replacement commonly takes one workday, often 6-10 labor hours for a crew, when existing connections and ducts are usable. A more involved installation can take 1-2 days if venting, condensate drainage, gas piping, electrical service, or duct transitions need changes. Contractor labor commonly represents $1,200-$3,000 of a straightforward replacement quote.
Labor estimate: 6-10 hours × roughly $75-$150 per technician-hour, with crew size, overhead, and bundled pricing affecting the final amount. Scheduling during a cold-weather breakdown can limit equipment choices and increase urgency charges; planned replacement allows more time to compare equivalent bids.
Which upgrades and repairs can be skipped without wasting money?
For a heater, compare models by wattage, safety certifications, thermostat control, tip-over protection, and warranty rather than assuming a premium design heats a room more cheaply. Most plug-in resistance heaters turn electricity into heat at similar rates for a given wattage. A timer or thermostat can reduce unnecessary runtime, but it does not make the unit more efficient while it is actively producing the same amount of heat.
For a furnace, obtain at least three itemized quotes for the same capacity range and efficiency tier. Ask whether the proposed size is based on a load calculation rather than simply matching the old unit. Avoid paying for efficiency upgrades without comparing the expected annual fuel savings with the added equipment and installation expense, particularly in a mild climate or a home with low heating demand.
Repair may cost less than replacement when a furnace has a limited, isolated fault. Common diagnostic and repair visits may run $100-$600, with major component repairs potentially reaching $1,000-$2,000. Compare the repair quote, equipment age, parts availability, and expected remaining service life; a repeated expensive repair on an older furnace may justify replacement, while a modest repair on a maintained system can be practical.
Control the heated area, avoid unnecessary furnace add-ons, and compare complete quotes before deciding which option costs less. Never use a space heater as a substitute for required freeze protection or a properly functioning heating system when temperatures could endanger occupants or plumbing.