
Home Problems
Why Is My Furnace Blowing Cold Air? 9 Causes and Easy Fixes
Furnace running but blowing cold air? Check these 9 common causes, from the thermostat fan setting to a dirty filter, and learn which fixes you can do yourself.
7 min read
Free tool
See how much your space heater costs to run per hour, day, month, and winter. Enter the wattage, hours, and your electricity rate for an instant answer.
The math is simple:
Cost per hour = watts ÷ 1,000 × electricity rate
For example, a 1,500-watt heater at 17 cents per kWh costs 1.5 × $0.17 = about $0.26 an hour.
| Heater setting | Watts | Cost per hour at 17¢ | 8 hours a day for 30 days |
|---|---|---|---|
| Low | 750 | about $0.13 | about $31 |
| Medium | 1,000 | about $0.17 | about $41 |
| High | 1,500 | about $0.26 | about $61 |
If your main heat is not keeping up, check our guide on a furnace blowing cold air before you rely on space heaters.
A 1500-watt heater uses 1.5 kWh each hour on high. At 17 cents per kWh, that is about 26 cents an hour, $2.04 for 8 hours, or about $61 a month if you run it 8 hours a day.
Heating one small room with a space heater and turning the thermostat down for the rest of the house can save money. Heating the whole home with several space heaters is usually more expensive than a furnace or heat pump.
Look on your electric bill for the price per kWh. If your bill has several charges, add the supply and delivery rates together. Many U.S. homes pay somewhere around 15 to 20 cents per kWh.
Yes. Most heaters use about 750 watts on low, which is half the cost of high. A heater with a thermostat also turns off when the room is warm, which lowers the real cost.

Home Problems
Furnace running but blowing cold air? Check these 9 common causes, from the thermostat fan setting to a dirty filter, and learn which fixes you can do yourself.
7 min read

Home Problems
Water on the inside of your windows every morning? Learn why windows sweat, what condensation between the panes means, and simple ways to stop it and prevent mold.
6 min read
Check the label. Most are 1,500 W on high.
Find it on your electric bill.
Per hour
$0.26
Per day
$2.04
Per month (30 days)
$61.20
Whole winter (Nov to Mar)
$308
Uses 1.5 kWh per hour and 12 kWh per day. Formula: watts ÷ 1,000 × hours × rate. This assumes the heater runs at full power the whole time. Heaters with a thermostat cycle on and off, so real costs are often lower.