Heating & appliances
Propane wall furnaces and space heaters: vented vs vent-free
A vented propane wall furnace or direct-vent wall heater sends its exhaust outdoors, and it is the right way to heat a room, cabin or addition with propane in a California home. Vent-free room heaters are a different matter: California's Health and Safety Code bars selling unvented heaters designed for use inside a dwelling, except electric heaters and decorative logs in a vented fireplace, so do not buy one for the house and never bring an outdoor propane heater inside.
Updated · American River Gas office, Newcastle
The main types
- Gravity wall furnace: set into an interior wall, with the vent running up through the roof. Common in older foothill homes and cabins.
- Direct-vent wall heater: a sealed unit on an outside wall that draws combustion air from outdoors and sends exhaust back out through the same wall. Some have a fan to spread heat.
- Vented freestanding stove: a propane stove that looks like a wood stove, vented through a wall or roof.
- Vent-free (unvented) heater: releases its exhaust into the room. Not for California homes, as explained below.
Vented versus vent-free
Every flame makes combustion products. A vented heater pipes them outside. A vent-free heater leaves them in the room you are breathing in. The California Air Resources Board lists carbon monoxide and nitrogen dioxide among the main indoor combustion pollutants and names malfunctioning gas appliances as a source of both.
California settled the question in law. Health and Safety Code section 19881 says no person may sell or offer for sale any new or used unvented heater designed to be used inside a dwelling, with exceptions only for electric heaters and decorative gas logs used in a vented fireplace. The narrow path it leaves for approved unvented logs and fireplaces applies to natural gas models, not propane. You may still see vent-free propane heaters sold online for other states. Skip them for the house.
Where a wall heater makes sense
A vented wall heater is a good fit where running ducts is hard or not worth it: a cabin, a cold back bedroom, a converted garage, a shop or an ADU. It also works as a second heat source in a house with a heat pump or an electric system, because it keeps heating on propane when other equipment is struggling.
Placement has rules. Propane is heavier than air, so California's Mechanical Code bars propane appliances in pits, basements and similar low spots unless there is an approved way for unburned gas to escape. Your installer and the local permit office confirm what applies to your building.
Heat without electricity
Some gravity wall furnaces and direct-vent heaters use a standing pilot and a millivolt valve that makes its own small current, so they keep heating when the power goes out. Fans and electronic thermostats stop, but the burner keeps going. Others need power for ignition or a fan to run at all. If backup heat during a PG&E shutoff is the reason you are buying, confirm in the manual that the model runs without electricity.
Space heater safety
The U.S. Fire Administration says heating was the second leading cause of home fires in 2021, and that portable heaters were only 3 percent of home heating fires in 2017 to 2019 but 41 percent of fatal ones. Its rules apply to any heater in the house:
- Keep anything that can burn at least 3 feet from every heat source.
- Turn space heaters off when you leave the room or go to bed.
- Never use an oven to heat your home.
- Have heating equipment inspected by a professional every year.
Outdoor heaters stay outdoors
Cold outages tempt people to bring an outdoor heater or a camp heater inside. Do not. The Propane Education & Research Council says outdoor propane heaters should never be used indoors or in enclosed spaces, and propane cylinders should be stored upright outdoors, never inside. A vented heater or a propane fireplace that runs without power are the safe ways to keep warm.
Installing and caring for a wall heater
A new wall heater gets a leak test at hookup and its own shut-off valve within 6 feet. Have the burner, pilot and vent checked each year before the cold weather, and keep the vent cap outside clear of brush and snow. California law requires carbon monoxide alarms in homes with fuel-burning appliances, so put them on every level and outside sleeping areas. Let us know when you add a heater so your tank size and delivery timing keep up. If you smell gas, leave the building first, then call 911 and us from outside.
Questions
Straight answers
Are vent-free propane heaters legal in California?
California Health and Safety Code section 19881 prohibits selling unvented heaters designed for use inside a dwelling, other than electric heaters and decorative logs in a vented fireplace. Use a vented or direct-vent propane heater instead.
Will a propane wall heater work during a power outage?
Many gravity and direct-vent models with a standing pilot and millivolt valve do, though fans stop. Check the manual before you buy if outage heat is the goal.
Can I use an outdoor propane heater inside during an outage?
No. Outdoor propane heaters must never be used indoors or in enclosed spaces. The carbon monoxide risk is serious.
Do propane wall heaters need yearly service?
Yes. Have a qualified technician check the burner, pilot, vent and gas connection each year before cold weather, and keep the outside vent cap clear.
Is a wall furnace good for an ADU or shop?
Often, yes. A vented wall heater warms one space without ductwork. Have it installed to code with a leak test and a shut-off valve within 6 feet.
Related
Keep reading
Sources: California Health and Safety Code section 19881 (unvented heaters) (opens in a new tab) · U.S. Fire Administration: heating fire safety (opens in a new tab) · California Air Resources Board: combustion pollutants and indoor air quality (opens in a new tab)
Newcastle yard · since 1966
Questions about propane?
Call the office and talk to a real person. Or leave your details and we call you back.
Monday-Friday 8:00 AM-4:30 PM (closed noon-1:00 PM)
After hours, weekends and holidays, our answering service reaches a staff member.
