Last reviewed: September 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards
44% of US homes that use heating also use a second heat source, and 28.1 million households run portable electric heaters: about 46 million of them.
Most secondary heat comes out in cold snaps, but 21% of homes that use it do so all or almost all of the time, which is usually a sign the main system is not keeping up.
Most discussion of home heating is about the main system. EIA’s Residential Energy Consumption Survey also asks about the second one: the fireplace, wood stove or portable heater that households use alongside it, and how often. Plug-in units fill the same supplemental role; our electric fireplace guide shows what one heats and what it costs to run.
How many homes use secondary heat
| Measure | Value |
|---|---|
| Homes using secondary heating equipment | 51.8 million (44.0% of heated homes) |
| Households using at least one portable electric heater | 28.1 million (22.8% of all homes) |
| Portable electric heaters in use | about 46 million |
| Users with two or more portable heaters | 45% |
How often it is used
| Frequency | Share |
|---|---|
| All or almost all of the time | 21.1% |
| At least once a week | 18.2% |
| A few times a month | 9.1% |
| Only when very cold | 39.0% |
| Only in rare situations | 12.7% |
The largest group, 39%, uses secondary heat only in very cold weather, which is what it is for. The group to notice is the 21% who use it all or almost all of the time. A home that runs a second heat source continuously is usually one where the main system is undersized, failing, or losing heat through the envelope faster than it can be replaced.
That connects to the building itself. One in five US homes is poorly insulated or not insulated at all, and renters are far more likely to live in drafty homes, as our analyses of insulation and renters and owners show.
Who leans on it most
| Main heating fuel | Uses secondary heating |
|---|---|
| Propane | 63.3% |
| Fuel oil | 56.4% |
| Natural gas | 45.0% |
| Electricity | 36.9% |
The pattern by fuel is the clearest in the data. Households heating mainly with propane or fuel oil, the two most expensive heating fuels, are the most likely to use a second source: 63% and 56%. Electrically heated homes are least likely, at 37%. A wood stove or space heater is often a way to run an expensive main system less, which our heating bill analysis puts in context: oil-heated homes spend the most of any fuel.
| Census division | Uses secondary heating | Of those, use it all or almost all the time |
|---|---|---|
| Mountain North | 51.2% | 22.8% |
| East South Central | 50.1% | 20.7% |
| West North Central | 48.6% | 22.6% |
| New England | 47.2% | 26.3% |
| Pacific | 44.0% | 17.7% |
| South Atlantic | 43.4% | 18.7% |
| East North Central | 42.3% | 25.5% |
| Middle Atlantic | 42.3% | 24.9% |
| West South Central | 40.9% | 15.4% |
| Mountain South | 39.7% | 20.0% |
Regional differences are smaller than the fuel differences. Secondary heating is most common in the Mountain North and least common in the Mountain South, but the share using it constantly is highest in New England, where old housing and oil heat meet cold winters.
The safety record
Portable heaters are also one of the most recalled categories of heating equipment. CPSC has announced 16 recalls of space and portable heaters since 2015, covering about 2.3 million units, mostly for fire and burn hazards. Every recall is listed in our HVAC recall registry, and running costs and fire data are in our space heater explainer. The fire and CO toll is in our home heating fire statistics and carbon monoxide death statistics: portable propane heaters are linked to more CO deaths than all furnaces.
Frequently asked questions
How many homes use a space heater?
28.1 million US households, 22.8%, used at least one portable electric heater in 2020, using about 46 million heaters in total, according to EIA’s Residential Energy Consumption Survey.
What is secondary heating?
Any heating equipment used in addition to a home’s main system, such as a fireplace, wood stove or portable electric heater. 44% of US homes that use heating, 51.8 million, use secondary equipment.
How often do people use secondary heating?
Mostly in cold snaps. Of homes with secondary heating, 39% use it only when it is very cold, but 21% use it all or almost all of the time, which suggests the main system is not meeting the load in those homes.
How many space heaters have been recalled?
CPSC recall records since 2015 include 16 space and portable heater recalls covering about 2.3 million units, most for fire hazards. Our recall registry lists each one.
Is relying on a space heater a sign of a problem?
Often. Using secondary heat all the time usually means the main system is undersized, failing, or the home loses heat faster than the system can replace it. Drafts and poor insulation are common causes, and our insulation analysis shows how common they are.
Are space heaters expensive to run?
They convert electricity to heat one-for-one, so per unit of heat they cost more to run than a heat pump and usually more than gas. Our space heater explainer works through the running cost and the fire data.
Methodology and limitations
- Source: EIA Residential Energy Consumption Survey 2020 public use microdata v7. Variables: EQUIPAUX (secondary space heating equipment used), USEEQUIPAUX (how often), NUMPORTEL (number of portable electric heaters used). Weighted with NWEIGHT.
- Secondary heating shares are of homes that use space heating. Portable heater shares are of all homes.
- Total portable heaters is the weighted sum of the number each household reports using, so it counts heaters in use, not heaters owned.
- Standard errors use EIA’s Jackknife method with 60 replicate weights; the secondary-heating share has a standard error of about 0.4 percentage points.
- Recall figures are from CPSC’s recall database via our recall registry, excluding re-announcements of earlier recalls.
- Collected in 2020. The 2024 RECS space heating detail is scheduled for spring 2027.
Sources
- US Energy Information Administration, RECS 2020 public use microdata.
- US Consumer Product Safety Commission, Recalls database.
The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.
Leave a Reply